Worst Engines of All Time: GM's 2.5L Iron Duke 4-Cylinder

[@63bbray]

I was a fleet mechaic for many years. Loved the 'Iron Duke', sure it was crude but very reliable, easy to work on and very inexpensive to operate.

[@nathanpilon6806]

I’ve had several iron duke engines in S10’s and found the engine to be quite reliable. Easy to work on too.

[@weasel884]

I second that.

[@Adrian-mq5ld]

its actually one of the most reliable engines ever made....yea its weak asf ,its funny to have it on Firebirds and camaros ...heck so rare I can't find videos on youtube with that engine in 3rd gens lol

[@Terminxman]

Yeah they’ve been used in the USPS LLV for decades now. They’re widely considered to be tough

[@michaeljohnson4204]

You said it all, when you mentioned the S10 that is not a truck but a miniature.

[@Creeperboy099]

I think the main issue wasn’t really as much the engine itself, but how the electronics (ECU?) were prone to short circuiting if there was a fluid leak which would catch fire

[@3beltwesty]

My 1982 2.5 L iron duke has 300k miles with good compression on three cylinders and #4 by the firewall runs 10 to 15 percent lower. I suspect the head gasket is going since it tends to foul the #4 plug a lot more. The valve cover has never been removed and i bought the car new in 1982.

[@thefinalroman]

might be a valve seal

[@evanc6110]

What car is it in just curious

[@garylangley4502]

@@thefinalroman That is exactly what I was thinking. My '84 Citation was burning some oil, but the deposits on the spark plugs were only on one side of each plug. This told me that the oil was leaking through the intake. I took the head off, and the valve guides were worn. I bought a rebuilt head (clearance sale at a machine shop), and the oil burning stopped.

[@errorsofmodernism9715]

I guess it just goes to show as PT Barnum said, "there is one born every minute"

[@nicklacerte7134]

Impressive

[@edwardpate6128]

I recall several friends back then having this engine and it proved to be pretty durable.

[@shadowwolfmandan]

Durable yes, gutless and leaky - also yes.

[@Tommy_Mac]

I called it the Iron Puke. I had one in an 82 FWD Buick, X car. It was gutless but got pretty good mileage. I had a 3.0 version in my last boat and I had zero trouble with it. Had enough power to move a 19' pretty well.

[@don2deliver]

@@Tommy_Mac The licensing for the 3.0L was sold to PSI and is still used in some Chinese Forklifts.

[@Tommy_Mac]

@@don2deliver it's a fairly common Mercury Marine engine, too. I guess MM get them from PSI.

[@jpaz4901]

@@Tommy_Mac not exactly the same in marine applications, GM does the block merc or omc bores the block and uses their internals for marine duty.

[@21stcenturyfossil7]

GM sold millions of Iron Duke powered cars. Everybody who bought one knew about the crudeness and roughness before they paid for it. I'd save the "worst" designation for engines that were prone to giving their owners nasty, expensive surprises.

[@nlpnt]

Agreed. The oldest working fleet vehicle you saw today was probably a postal LLV. Guess what's powering those. The fact that the engine's level of refinement is just about suitable for a mail truck is neither here nor there.

[@davidperry4013]

@@nlpnt they should make new FWD LLVs with 1.5 liter turbo 4s or better yet a 180 hp fully electric power train.

[@elijahwatson8119]

@@davidperry4013 turbocharged engines wouldn't be that useful for postal use. They just don't need the additional power. A modern naturally aspirated 1.5l i4 would put down more power than the old iron duke did new - let alone with 30 years of wear on it.

[@greendryerlint]

@@nlpnt These engines always reminded me of the original Willys "Go Devil" engines with their vibration and sound.

[@Prestiged_peck]

@@elijahwatson8119 they'd probably still need a 2.0l

[@scottfelsted3203]

I loved this engine. It was noisy because the cam was gear driven. It was bullet proof.

[@rickhibdon11]

And the cam gear was not metal. It was a sort of fiber based plastic. It wore quickly and made the engine knock. The fix was replace the cam gear. Step #1. Remove the engine. Later on techs found a way to short cut it, but for years it was remove the engine

[@blurglide]

Yeah it sounded like it'd explode if you revved it at all, but it was reliable. Tractor engine.

[@scottfelsted3203]

@@blurglide LOL, Mine must have had great sound deadening! The timing gear could be noisy....

[@DejaView]

@@rickhibdon11 You always know your in trouble when Step # 1 in the shop manual says "Remove engine to perform the following procedure" Lol... Years ago a friend & I did a timing belt on a little Isuzu/Chevy Spectrum. He said "That engine is not coming out of this car for a belt!" We thought about it for a while, removed a transaxle mount on the opposite side so we could tip the engine to the right & it left us get a socket on the crank pulley. Can't imagine we were the only ones to think of that...

[@HowardJrFord]

The rattling noise these engines made was from the pistons . They had too much clearance in the pin area , which caused them to rattle .

[@DKSE123]

The GM iron duke was one of their better engines back then . Easy to repair , long lasting & fairly efficient on fuel . The post office still uses them

[@scdevon]

Of course it's reliable. It lives life below 3500 rpm. A farm tractor engine with the benefit of fuel injection so no fuel washed cylinders in cold weather, had gear to gear timing, etc. So buzzy and boring and low on power it's almost love-able.

[@davewallace8219]

yes they do....but usp. is a poor example...still funny..thanks

[@paulmckinney6163]

@@davewallace8219 more like the USPS is still stuck with them.

[@sodiebergh]

Another gem. My dad's brand-new for '86 Olds Cutlass Calais had this engine. In 10yrs the car just about fell apart, no paint, plastic interior disintegrating, but that Iron Duke kept on clattering 🤗

[@spaceghost8995]

Haha yeah those GM cars were just junk at that time! My Mom had a 1983 Buick Regal. Absolute garbage. Rattled apart as you drove it. Everything went bad, power windows, wipers, door seals, trunk latch, door handles fell off, rearview mirror fell off, domelight fell apart, heater controls started going out, rear bumper rusted and FELL OFF on one end! HAHA

[@michaelyounger4497]

I had an 80 sunbird with an Iron duke. It was a legendary engine. It injested water in a flash flood but kept running so I could drive out of water so deep the car was floating..saved my life. It ran 90 miles in August in the desert after loosing a waterpump..it actually could successfully air cool..new pump and away it went.. it was cheap and simple to fix, they are noisy with the timing gears..but indestructible cheap and reliable. I would joyfully buy a car with one.. they never made much power, but that wasn't what it was designed for

[@lastotallyawesomebleach204]

I thought the Calais had the quad 4

[@steveengelbrecht7271]

The worst thing about the iron duke was the fiber timing gears. That’s why it was so noisy. Those timing gears could be replaced with steel parts.

[@cadillacguy1890]

The auto parts store I first worked at had a 1977 Pontiac Astre wagon delivery car. It had the Iron Duke. It took almost 80,000 miles of delivery abuse (regular visits to redline, minimal maintenance, oil changes maybe once every 10,000-12,000 miles, probably one new set of plugs, not much else). It finally threw a rod one cold (10 degrees Fahrenheit) morning when we were warming it up for the day, running on cold idle (1700 RPM or so). The rod went down through the oil pan. There wasn’t 2 quarts of spilled, black as sin engine oil on the ground. I think it did pretty well durability wise considering. It was definitely noisy and rough.

[@matt8151]

We ran one for years in a mid eighties Buick Century taxicab - almost ideal in that use, went huge numbers of miles, reliable & economical.

[@alan6832]

Quiet smoothness is not it's job. It's an economy car engine! and a good one. They should have put it in larger utilities like fullsize pickups, Astro and fullsize vans! especially Astro!

[@TheBrokenLife]

@@alan6832 I'm kind of surprised it wasn't an option for Astro since they're just S10s, but good grief you could have walked faster than one of these things in a fullsize truck. Towing/hauling capacity would have been dictated exclusively by tailwind.

[@davidcarder6364]

@@alan6832 really, you want a 90 horsepower engine in a full size truck and van,it wouldn't move eather one.

[@billdang3953]

Wonder how it would do as a marine engine?

[@billdang3953]

@@davidcarder6364 Consumer's Reports would probably say how great it is.

[@austincjett]

I've owned several vehicles with that 4 banger. With oil changes, most of the engines outlasted the rest of the car. The biggest problems they had was the crappy complicated carbs and then early generation fuel injection. Not to mention the dozens of low-quality vacuum hoses that were prone to crack and leak. It's not fun when a 4 banger is idling on 3 cylinders at stop lights.

[@Bassdude98]

this is the exact issue im having with my 89 s10 right now! I thought I was going crazy when I realized that I was only running all 4 cylinders when I was accelerating. Ill have to go through and check all of the vacuum hoses.

[@gregorymalchuk272]

​@@Bassdude98Did you ever figure out that problem? Was it running rich or lean?

[@jsciarri]

Completely disagree on the Iron Duke being one of the worst engines of all time. The engine was used in many GM cars and trucks of the time, industrial, and marine applications. We had one in a 1989 Buick Century for many years and a couple of hundred thousand miles. The engine was pushed hard and never had any sort of issues or problems and got excellent fuel mileage. Every person tells me the same about how reliable the engine was. In my opinion this engine possibly could be considered to be on the best GM engines of all time list.

[@DejaView]

I totally agree with you. It may not have been ultra-refined but definitely not a bad engine! I owned 2 of them. (Both Chevy Citations. Did need an oil pump in one of them, but no other problems to speak of). As to vibration, neither of mine nor any others that I had experience with seemed all that bad. In fact I thought they were quite good compared to other large 4cyl engines. It's easy to say the import engines were smoother but few of them were even as big as 2 litre at that time & vibration seems to be less prevalent in 4cyl under the 2 litre mark. The engines I was familiar with that I thought were really crude & rough were 2.2 litre from Chrysler. Place I worked in mid/late '80 had 2.2 litre Plymouth Horizon & Voyager. When you dropped them in "Drive" they would sit there with the steering wheels shaking up & down about 2 inches! That was ridiculous. Never had that in any of the GMs.

[@fromthebackofmymind]

This "worst engine" was popular in Dirt Track Cars. There was a Marine version as well. Postal vehicles STILL Running this engine. Imagine uploading this video and all the negative response for talking out of your @$$ about a subject your not well schooled on. I would love to find the Offy 4bbl intake for one of these. Comp Cam kit and 2 gear timing set. Pushrod inline 4. Tough hombre.

[@timdixon9224]

A straight 6 cylinder engine is still the best design of anything yet.

[@lukepokrajac1057]

From a balance standpoint absolutely. Perfect balance.

[@bobcarlino2806]

Agreed!!!!

[@RockandrollNegro]

Or, providing the engine bay is long enough, a straight 8. Those old Buick and Cadillac straight 8s were known to run decades, with minimal servicing. Not very powerful in comparison to a V8, but inherently more reliable.

[@martin-vv9lf]

500cc per cylinder seems to be the most efficient so that's why we don't see the larger engines in economy. The boxer twin the citroen 2cv used is balanced. i'm surprised that we never saw a modern version with overhead cams and liquid cooling. I guess it's too expensive to fit two turbos.

[@matthewbanta3240]

I've said it before, and I'll say it again, you could have done a lot worse in the 80's than an Iron Duke. Of course that probably has more to do with there being so many bad engines in the 80's than the Iron Duke being a good engine.

[@TheREALJosephTurner]

Had this engine with a manual in a 79 Sunbird (a RWD Monza rebadge back then), when I was a teenager in 1989. Still one of the best and most reliable cars I've ever had. What it lacked in speed, it made up for with impressive clutch-dump burnouts.

[@unlistedpuma4543]

Those 4 bangers do a burnout?! I’ve got an 80 Sunbird with the Iron Duke and 4 speed, and I’ve never tried a clutch dump, how well does it do it?

[@jimsix9929]

yes they are almost unbreakable, look at my post above about the 1985 Indy pace car

[@nolanbrown84]

1990. I was six and my parents had just split up. Things were ugly and we didn't have much money. After the split my mom needed a decent vehicle. Her and my grandpa went down to a local used car dealer and purchased a two tone brown and tan 1984 two door S10 Blazer. 4wd with a manual. Cute little thing. I hated it because it wasn't the k5 Blazer I had grown up in though. However, I look back with so much fondness for that little iron duke powered Blazer today. I just can't help but smile everytime I think of it, or see it! Yes it's still around.. My mom drove that little thing nearly through my highschool years. So you can imagine all the school sporting events that she went to over the years. It finally ate a head gasket and at the time, I didn't have the knowledge or knowhow to do anything about it. So she sold it in favor of a 94 two door s10 Blazer. The guy who bought it rebuilt that iron duke and I still see him from time to time. I always ask him how it's getting along and he always gives me all the updates on it. I've requested that if he ever decides to sell it that he give me a call. He graciously agreed to that. It had to have had a couple hundred thousand on it when the head gasket went so I can't imagine now. Funny that a discussion of the 2.5 iron duke can bring me both good and not so good of memories. All I know is that that little blazer never stranded us even once in all those years. Great video as always. *Edit: I realized the first year of the s10 blazer was 83 and not 82 so I had to check with my mom and she said it was a 1984. Just wanted to clarify that.

[@highwayman1218]

Great story! 👍👍

[@auntbarbara5576]

Aunt Barbara adores that story! 👵😐

[@mph5896]

Fun story. Cant believe they put that small of an engine in one of those.

[@nolanbrown84]

@@mph5896 looking back I totally agree with you! I had no idea how underpowered it was when I was younger. I just remember so vividly the way the Blazer felt as I was sleeping in the backseat on road trips. That little engine definitely had its own vibration as opposed to a 4.3 or even a 2.8.

[@CORVAIRWILD]

@@nolanbrown84 the 4x4 S10 Blazers got the 2.8, my friend called it the struggle 6, until GM finally put the 4.3 (a 305 V8 missing 2 cylinders), and those sucked gas, then they got the plastic fuel spider under the intake

[@jewllake]

I had a 1991 Pontiac Grand Am; best trouble free car I've ever owned. Drove it over 200,000 miles and sold it to a friend of mine. Headliner never sagged and it had the original fuel pump and the Tech 4 2.5. Mine had V belts but it ran smooth for the most part - had plenty of power to always spin the p205 65 r 14 tires off the line and had plenty of passing gear power all the way up to 80 mph. After 80 it would stay in 3rd but still pulled pretty good for what it was. The timing gears were very quiet until one day I beat on it pretty hard at 40,000 miles then they started making the normal 2.5 gear drive rattle.

[@robertstout6980]

For an economy engine designed in the 1950's and released in 1960 I'd considered it a quite successful engine. The cam drive was the same setup as the Chevy 235. Pontiac dug it out and revamped it because they couldn't stomach being stuck with the stigma of the Vega engine. The Iron Duke also didn't have the oiling troubles of the Y block Ford or the valve train troubles of the big block Chevy. While I don't consider it a great engine I certainly wouldn't put it on a worst list.

[@itsthatguy5742]

I came up in the 80’s. I’m a tech and I remember those engines. I agree with you. They were reliable and long lived, also unrefined. I didn’t care for them because they were overshadowed by engines like the 3800.

[@jimpurath239]

This engine had few internal problems. It was reliable in the later 80s and 90s. Noise was fixed by newer cam and crank gears. It was pretty durable

[@robertlemaster7525]

I don't know all that much about it, but if my good friend Bryan, a Ford freak, would say that it was a good engine for it's time it can't be bad at all. Plus it's good enough for Jeep to use at the time as well. Only they got noticably more power from the same block.

[@tedmartin4882]

Yes and Chrysler 2.2 was worse

[@sking2173]

@@tedmartin4882 - When the 2.2 went to fuel injection, it became a good running engine ...

[@stoneylonesome4062]

The Iron Duke should’ve been a Soviet Engine.

[@ironhead2008]

Brutally simple?: Check. About as refined as GULAG moonshine?: Check. Damn near impossible to kill?: Check. Yep, would have been at home in a Lada.

[@TheBrokenLife]

I suspect a Soviet engine of that size would be about 20hp though.

[@mpetersen6]

@@ironhead2008 Even a Lada had an OHC. IMO if Pontiac was Iintent on building a 4 in that size range they would have been better of to resurrect the OHC six built as a four banger.

[@stoneylonesome4062]

@@mpetersen6 I wish they had continued the OHC I6. It would’ve been nice if they had taken it to the full extent, DOHC, cross-flow, all-aluminum, turbo, fuel injection, etc. The closest thing we ever got to that in the USA was the VorTec 4200 I6, often called the “American Barra”. Even ford australia gave the 300 I6 a Dual-cam head and turned a truck engine into a powerhouse.

[@johndaut2838]

The original 60's and 70's Iron Duke you could not hurt. It was half of a 283 V8 and came in Chevy 2's and other GM cars. I even had one in a 1974 CJ3 Mail Jeep and drove it once a month from Houston,Texas to Shreveport, Louisiana and back for Navy Reserves and drove it every day 150 miles round trip to work for 2 years. Sold it running like a top and the guy I sold it to drove it another 10 years. It had over 200,000 miles without a rebuild.

[@kalebaldwin5398]

They're slow and ridiculously crude, but they're unkillable. Which is why the best application for them has been in the Grumman LLV mail trucks (essentially a 2wd S-10 Blazer). The tractor-like engine noise pretty much serves as a siren. You can hear them a mile away.

[@Ascotman]

You have that tractor-like engine noise right on! I can tell when my mail is about to be delivered from a long distance away by that engine sound!

[@mikasantos3774]

My Iron Duke has almost 300,000 miles on it never left me stranded anywhere she's finally getting tired due to lack of oil changes the motor pretty worn out lots of blow by nowadays still starts and run every time takes me whenever I got to go right up till this day I'm going to end up doing a V8 swap in my S10 but I will still keep the good old Iron Duke on the side for another project and redo the engine and make her nice and fresh

[@captkirk6145]

Had a few of them in S10s. Ran a company that used them for delivery. Didn't have a lot of problems with them. Couldn't get out of there own way but would easily get over 200k. When they switched to the 2.2L then the real problems started!

[@hrcnick11]

Same had 225K on my S10 with a 5 speed, never had to do anything to engine, clutch or transmission. Just a water pump, coil and exhaust gasket. Replaced two rear ends and some brakes but was reliable as can be never left me stranded. But I also had a Chevette with 185k so maybe I am just lucky I sure did beat on them.

[@don2deliver]

This engine has delivered half of all the mail to most US houses for 34 years. It's not refined or powerful, but no way is it one of the worse

[@billsmith8591]

One of my Uncle's had the EXACT opinion of the Iron Duke as you described. He had a 1977 Buick Skylark with a 350 V8 and in 1982 wanted to trade it in for a new Skylark. Well when he first looked at the new Skylark, he was rather impressed with it, even though it was a good deal smaller than his current car. He was surprised at the roominess of the interior for being a smaller car. He found a 2 door that he liked in the color and options he wanted and went for a test drive. When he started the engine, he changed his mind immediately !!! At idle it shook the whole car so badly he thought the factory put in defective motor mounts. He also said that his Stepfather's John Deere tractor was quieter and smoother running !!! He instead opted for a Buick Century coupe with the V6.

[@br54985]

Hi Adam, for what its worth ive had several iron dukes and always had good service from them.I do agree they were very industrial but they were good for what they were.

[@robertokandal]

the engine is very good but sometimes Gm make stupid things time to time, like Plastic gears timing.. lol

[@StevieinSF]

My 1983 Omega had an Iron Duke in it. Yes it was noisy and rough at idle, but not bad. Had vapor lock problem due to bizarre fuel injection set up. The rest of the car fell apart, the engine still was OK.

[@davesherman74]

My folks had an '88 Pontiac 6000, it's what I learned to drive in. I can still hear that engine, it just had this distinct sound. Other than having it eat the cam gear on the highway at 100,000 miles, it was still going strong at 190,000 after dad and I replaced the cam gear ourselves. The body rot was pretty bad on the car by then, I think he got a whopping $100 trade in, but the engine was still running like a watch.

[@billbishop7814]

Had four iron duke equipped cars including my wife's 1980 AMC Concord. Never a problem outside of normal wear and tear parts. They did all have leaky valve cover gaskets, fixed by the FelPro rubber coated steel version. Still have my '86 Ciera that draws a croud at car cruises with the hood open displaying the Duke in all it's glory. Yes, everyone claims to have owned a car with one in it!

[@richardprice5978]

so at one point jeep used it same for mopar? so the 4.0L missing 2 cylinder's?🤔

[@KC9UDX]

@@richardprice5978 no. AMC developed their own new 4 cylinder engine, the 2.46L, which the 4.0 is based on. The 2.46L (unfortunately) has the same bellhousing pattern as the 2.5L, so that they could directly replace the 2.5L with the 2.46L. Incidentally, the 2.46L is a great demonstration of what AMC could do. The 2.46L is better than the 2.5L in every way.

[@richardprice5978]

@@KC9UDX still not convinced enough as continental engines could have designed both of them and the earlier jeep/buick/oakland/GM/AMC/ ford model T and A castings had the bell a separate part just like Cummins 4or6BT is, and tooling is time consuming and expensive pre-CAD to make and modifying parts are easier to do in that ara or a carful rebage job so the average joe doesn't know or find out

[@KC9UDX]

@@richardprice5978 well I happen to know and have known quite a few people who were there, and can say with confidence that AMC did their own engine design and development. (I was once in the tooling business) They had a long, long history of it, anyway. You don't have to believe me; look at the design. The only things in common are the bellhousing pattern (a matter of convenience at the time), the fact that they're both 4 cylinders, and the fact that they have similar displacement. Otherwise, the design of the AMC 4 is much more like their own 6s than the iron Duke. The displacement is similar on purpose. It's one cubic inch smaller, to demonstrate that they could build a better engine with less.

[@richardprice5978]

@@KC9UDX ok wouldn't know you where in the automotive tooling business so its not any disrespect towards you or your collages and my background is working/fixing car and moved in to manufacturing mechanics ( and being in a automotive plant is kinda on my list but for now i ended up working on packaging equipment ect ) and have wanted to design/engineer power trains or crash safety but 15 years ( really from the age of 4 to about 30-something so i respect the people behind the magic curtain in wizard of OZ so to speak as most of the credibility goes to the board room or marketing/beanies but a good car company needs the rest of the team to function correctly probably more so as ie a badly engineered or executed design can leave a sour taste in people's mind's long after the production ended ) later in 2020 sofar hasn't happened yet, so how does continental and Oakland tie in to this as i found some paperwork and historical that points to that

[@nasedo3129]

A guy I worked for back in the 80's got 41 mpg hwy in his Citation with an Iron Duke and a stick. Nuthin' wrong with that.

[@DejaView]

Just left a comment elsewhere. I used to do a consistent 38 mpg from PA to Vermont, running about 65mph with 84 Citation, Iron Duke, throttle body injection, 3spd THM-125C auto (w/ lock-up converter). Went from PA to Vermont & still drove a day or two before filling up. Not particularly fast or powerful but geared right that I did any hill in Vermont without undue stress & wasn't holding anybody up. Gas prices being what they are, wish I had a modern car that could do that!

[@SomeOne_86]

@@DejaView any modern economy car will do that. Honda fit, toyota aygo, vw up, whatever.

[@DejaView]

@@SomeOne_86 show me one with a 20 cu/ft trunk. That's what the cargo area was rated WITH cargo cover in place. (even greater with cover removed) 5 people could go for a 3 day ski weekend, ONLY the skis were on the roof. Luggage, poles & 10 ski boots all in the trunk... The newer cars are undoubtedly going to be quicker in spite of smaller engines but in the highest MPG "mini-cars" are we still factoring in automatic transmission?

[@SomeOne_86]

@@DejaView Toyota Rav 4 Hybrid has 37.6 cu ft of trunk space, can seat 5 people easily, and gets 40mpg. Also did I mention it has AWD, 220hp, 11 speaker JBL audio, dual zone automatic climate control, heated front and rear seats, ambient interior lighting, a 5 star NHTSA safety rating... Man you have to understand that technology advances over time.

[@yabbadabba2887]

Our family ride was an 80 skylark with a 4 speed manual. My dad regularly got 42-46 mpg on the highway

[@ronniefoster5099]

Sorry, but there are many engines that were way worse running and way less reliable. These were definitely not the "Worst Engines of All Time".

[@MrTubeamps]

Spot on review. One thing these engines were good for were marine applications. I had one in a mid 80's 17' Sea Ray. It made 120 hp, which was adequate, it was fuel efficient, and extraordinarily reliable. The hull and engine cover did a fairly good job absorbing the noise and vibration. I miss that old boat.

[@1dollarten]

The marine engine was designed back in 1962 . Completely different program. The Duke was a metric engine and the marine engine was SAE dimensioned

[@mattt198654321]

If anyone can imagine the sound of a mail truck (Grumman LLV), those still run the iron puke to this day. Guess they couldn't be all that bad!!

[@bdcasey11]

An llv will eat an iron Duke in 1-5 years depending on how many miles they drive every day

[@someguitarguy.]

I just don't see calling the Iron Duke a "worst engine" because it's simple and rugged, as was intended. I have a 96 Lumina with the Vulcan engine and wish it had the Iron Duke. Chances are, your mail is delivered by an Iron Duke.

[@ponchoman49]

While a bit crude and noisy I wouldn't call it the worst of all time more like a middle of the road reliable but not too pleasant engine. By 1987 it was smoothed out with balance shafts on the stick shift cars and 1988 with automatic transmission and was a decent engine from that point forward. We used to upgrade the dog bone motor mount to the Moog that was hydraulic and smoothed both the engine idle and transmission shifts. I would call the HT 4100, 5.7 diesel and Northstar engine in its early years as the worst from GM.

[@DejaView]

Had 2 Iron Dukes back in the 80's, both with the TBI system & THM125C. Both were reliable & reasonably trouble free. As to refinement I didn't think they were really all that bad, especially compared to Chrysler 2.2 litre that we had in several vehicles where I worked (idling in drive those steering wheels used to shake vertically to the tune of about 2 inches! Not acceptable!) You could feel vibration in the wheel from the "Duke" but they didn't shake like that. Wish I'd have known about hydraulic "dog-bone" replacement. Would have installed one...

[@darrengarcia4937]

Its fine for low rpm work like Postal vehicles but as a passenger car engine its awful.

[@michaelbenardo5695]

@@darrengarcia4937 It was a hell of a lot better than that Vega engine!

[@Rush-gu3ij]

I had one of these engines in an 81 Citation. It had what I believe was called the 2 Barrel Varijet carb. Two issue with the engine, never depress the gas pedal to restart if it was warm (it would flood immediately), which people I let borrow the car found out quickly if I gave them keys after driving it. Also had to change two ignition control modules, but you already have a video on those. Other than those issues it seemed to be bullet proof to a certain level of abuse from a college aged kid.

[@pcno2832]

My father bought his new in 1981 and the only two things that failed were the ignition control module and one of the stainless pipes between the engine and the converter. Not bad for a car with such a bad reputation.

[@peoriavideosltd6822]

We had a Citation for a few years in the mid-80s.... I remember when we got it, I was amazed because it seemed so fast! That may say more about the six-cylinder Nova we had before the Citation, but at any rate, in the 55-MPH era the Iron Duke was certainly adequate (and returned good MPGs too) in the little Citation.

[@1mikewalsh]

I got my dui in a 81 Citation, parking it in someones basement cost me dearly...

[@NDC1115]

Cam gear was made from phenolic resin, which was to combat noise. That gear was about the only thing that killed them. It was a good truck engine in my opinion

[@jwreck5281]

I work for the post office and the last of the llvs are equipped with this motor. After 34-35 years these are quite bulletproof

[@nerd1000ify]

The fiber gear was probably made of phenolic laminate, e.g. Micarta or Tufnol. Ironically, this material is usually selected to reduce gear train noise! The soft gear absorbs the high frequency vibrations that create gear whine. A hardened steel gear would no doubt have lasted longer, and not rattled due to wearing down. Fun fact about phenolic laminates: they can be adequately lubricated by water rather than oil. As a result they are a popular material for propeller shaft bearings on ships.

[@timbullough3513]

My parents had a 91 Calais with the Duke. It was extremely quiet when brand new. After say 20,000 miles there was a certain clatter associated with it. Like you say it was durable and reliable and economical. When I later got a Calais with the 'upgrade' Quad 4 ... well it was much louder, and hobbled by the 3 speed. The Duke was better than the Quad unless you enjoyed lots of repairs.

[@jewllake]

My 91 Grand Am was very quiet until 1 day I beat on it pretty hard then the timing gears started to make the clatter sound. That was around 40,000 miles or so. The Duke was a good reliable motor. It served me for 200,000 miles until I sold it to a friend.

[@jackdale9831]

Wasn't the "Quad" Great for "getting down the road?" {--for a 4 }

[@timbullough3513]

@@jackdale9831 maybe it was if it had the 5 speed? 3 speed automatic almost negated any extra power in what was on a test bench indeed a powerful DOHC all aluminum 4 cylinder 'motor'. The days when it ran right and at the right revs, yes it was pretty cool. Calais was a good looking compact to my eyes.

[@rolandocurro8842]

I hate hate hate hate that going to low idle speed when it was warm. You happened to have mentioned. On the POS iron duke from 1980. On my old forgotten POS Pontiac Sunbird hatchback. I had to take that POS back to the Pontiac DEALER about 6 times. Because when i had the A/C on while in " D " position on the tranny. It just couldn't stay on normal idle speed. Hated the car and hated the engine. With a passion. !!!

[@prevost8686]

After being a professional technician for 30 years I would respectfully say that anyone who thinks the Iron Duke engine was a great engine apparently has very low standards as far as what constitutes a great engine. It was a waste of good iron and steel.

[@mph5896]

I do recall they were somewhat reliable in comparison to some of the other junky engines at the time. Never would I consider spending good money on a car with that engine, but a beater in the mid 90's could be had for close to nothing with that engine still chattering along.

[@vilefly]

My 30yrs says that the motor was what it was......a basic, reliable engine that was rather noisy with no frills at all. Not sophisticated enough to race with in any class. Pretty tolerant with a lack of oil, since it leaked most of it.

[@michaelbenardo5695]

Most of us "regular" people mean super reliable and rugged, and easy to repair, when we say "great", not high-tech, aluminum, complicated with a rubber timing chain and the water pump inside the timing gear cover. That 151, and its 153 forbearer are Chevy 6s minus 2 cylinders, and that 3rd generation Stovebolt is heavily based on the small-block V8, a great engine. Not all of require 500 horsepower.

[@prevost8686]

@@michaelbenardo5695 And the Iron Duke doesn’t even come close to the quality of other engines of that time period. It would’ve been near the bottom .

[@michaelbenardo5695]

@@prevost8686 My definition and your definition of quality are very different then. To me, something that is very reliable, rugged, can take heavy abuse and still come back for more, and lasts a long time is high quality. To you, I think, high quality means innovative, lots of horsepower per cubic inch, capable of super-high RPM, and cutting-edge technology. Remember, the Vega engine seemed cutting-edge when it debuted. It was garbage.

[@andrewinaustintx]

Crude and rude - but durable. I had forgotten about the phenolic resin fiber timing gear. The Iron Duke's competitors had a timing belt- which many American owners only bothered to replace AFTER IT BROKE.

[@kellismith4329]

The ford inline 6 had the same set up

[@Spennyman10]

I'm not even going to watch this video. The 2.5 is one the most durable and reliable engines ever made. I've owned over 25 of them including one in my garage right now. It was bulletproof.

[@fredanddebramacdonald2445]

One other thing you didn’t mention concerns the oil filter. This engine was first designed for rear wheel drive applications, and when the engine was turned sideways for front wheel drive, the oil filter was a bear to change, as it was on the backside of the engine with a lot of stuff in the way!

[@terryprevost1527]

I had an ‘82 Buick Skylark I inherited and drove for a few years in the mid to late ‘90s and remember vividly how rough the engine sounded and the shake that came through the steering wheel at idle just as you described. That said, I never had a problem with it, very reliable. Thanks for another awesome informative video. I also had an 83 Impala wagon, with another possible ‘worst’ contender, the 700R4 transmission. Went through three of them in as many years, with only normal use. Curious if this was common experience.

[@josephthomas8318]

I had an S10 with an iron Duke and it was extremely reliable and got decent milage. He 254k miles when I finally sold it and it still ran strong. Honestly I've never heard anyone say a bad word about the old iron duke

[@daveallen8824]

Don't for get Pontiac's timing chain issues from the 60's. The nylon coated gears failed really early.

[@davewallace8219]

Buick had those too!

[@jhoncho4x4]

Sad GM already had the great 153 2.5 4 cylinder, that they had been making since the 1962 Chevy 2 Nova. Has been used with an outdrive in boats for decades by Mercruiser and OMC, when they existed. Takes a durable engine, to survive in boats, heavy load when boat is on plane. Same design as their straight six, with 2 center cylinders removed. I ran a 1969 2.5 in my boat for many years and it ran VERY smoothly and sipped fuel. An aluminum Starcraft cabin boat on water, will amplify any noise or vibration. At idle, could barely tell engine was running. Great for slowely trolling; quiet, smooth, no exhaust smell and used very little fuel. Could tow 2 tubes with kids on them, at 25 - 35 mph all day and burn 6 gallons of fuel. Never left me stranded or gave me any issues while on the water. Easy to maintain; change oil and clean the points for the season. Carried spare points, condenser and coil; never needed them. I and my friends, also had many iron dukes in S-10's and they failed, if used under hard loads; not nearly as good as the 153. The 153 must have cost too much to make and lasted too long in automotive use; industrial engine. The 153 (181) is still produced today, in it's 3.0 (181) form. Always wanted to try swapping a 2.5 or 3.0 into a small vehicle; uses standard chevy bolt pattern. May need to be an automatic trans; not sure if all of them have the thrust bearing for the clutch.

[@garyharrington5300]

I worked from 81 to 86 in a gm dealership ,I loved the 2.5 mostly because folks seemed to gravitate to the 2.8 v6 now that motor was a genuine pos ,carb with electric controlled jets ,leaking rope type rear main seal ,all for .3 more liters ,

[@highwayman1218]

Agree, the 2.8 was junk. The carbs on the 2.5 were junk too, best they did was go TB FI and they were anvils. 👍

[@wysetech2000]

A friend had a Celebrity with the Iron Duke engine. It always was a little noisy until it reached 100.000 and then you could barely hear the radio. I replaced the balance shaft assembly and was as quiet as new. By the time it hit 200.000 the car was very rusty so he decided to scrap it. Before we scraped it we tried to blow it up. We tried for 2 hours on the rev limiter until there was no coolant in it and dumping everything we could find down the throttle body until it finally ran out of gas. We added a little bit of gas we had around and when we started it, it ran like new. I used to call them a tractor engine but I gained a lot of respect for them that day.

[@Ahoderasan]

I'm from Brazil and I have a Chevrolet Opala, the car that was first equiped with the engine that gave birth to the Iron Duke. Mine is an 89 , carburated and powered by ethanol. This sounds bad but it isn't. Even though we didn't received the "improvements" that the US cars did I really like this engine. It vibrates a lot but if you set the iddling around 700rpm it becomes quite smooth and with a nice exaust it sounds good too. It's not fast but it offers a nice amount of torque which is ideal for city driving and fuel consumption. Also Brazilians used to call it the "sewing machine" because of the distinct noise it makes.

[@karltaylor5643]

I have a 1989 S10 with the 2.5L. It's doing just fine. About 209k miles. Still doesn't smoke and burn oil. It's no hot rod, but it works.

[@tommcmichael5278]

The sound of my youth! An endless stream of X- and A-body cars moaning up the hill in front of my suburban childhood home. The TBI Dukes had an especially distinctive sound.

[@anselpeneloperainblossom-s3489]

Sure it was crude. But how many Cadillacs got them? They were a basic engine for basic transportation. Something we could use today.

[@Doobie1975]

I thought they were decent engine's but definitely not one of GM's best, I heard they were better than the 2.8 Liter V6's on many early 80's GM vehicles.

[@scdevon]

Both engines were real shitters. I was a service tech at a GM dealership in the 1980s. There was a service bulletin on the 2.5 noisy fiber cam gears and the flat rate warranty time to replace them was pretty bad. The Tech 4 Iron Dukes went through a phase of broken head bolts too ; especially the center head bolts. These were really bad years at GM.

[@dougedwards8022]

2.8 was in bertta gt an was scary fast, oil ports in valve cover back to pan helps a ton ,high Rev suxs pan dry,oil returns to slow,ports to small,

[@MostlyBuicks]

My Uncle had a 1975 Chevy Monza with a 262 V8 and a manual 4-speed. It got 22-25 mpg on the highway. I KNOW because I used it for a month and calculated the fuel mileage myself. Now with an engine like this WHY, WHY, WHY would GM ever even want to develop these half-assed 4 cylinder engines in the first place? It has been my lifelon experience that the small block Fords and Small block Chevys typically are more efficient than the 6 and even 4 cylinder counterparts. Look at all the engineering and production costs GM could have saved just by using the 262 V8 in ALL the cars they put newly designed 4 and 6 cylinder engines in. The V8 design has the best potential for efficiency. Turbocharge a 4 cylinder? NO THANK YOU!

[@michaelbenardo5695]

Blame CAFE.

[@The_Future_isnt_so_Bright]

Im glad you mentioned the timing gear. Its a noninterference engine so no issue when the gear gave out. Cosworth made a Duke that cranked out 500+ rpms so they had potential.

[@SomeOne_86]

500? did you mean 5000? XD

[@The_Future_isnt_so_Bright]

@@SomeOne_86 Hp not rpm's, my bad, Spell correct is stupid sometimes.

[@SomeOne_86]

@@The_Future_isnt_so_Bright damn, they made a 500hp one? Was it turbocharged or supercharged?

[@howiefeltersnatch2973]

I believe turboed; but those engines shared nothing with the real production Dukes. The weak point of the Duke is the crank, usually good to about 180ish hp. A 3 liter Mercruiser crank(forged) can be machined down and used as a stroker crank

[@danielbennion80]

I don't think he knows what he's talking about. I had one in a 1981 Buick Skylark. Had plenty of power and got 29 mpg. The car itself wasn't so great for other reasons. I guess it depends on what the engine is in that makes or breaks it. It would likely be a little underpowered for a Camaro or an SUV, unless it could be geared sufficiently to make up the difference.

[@charger19691]

I always considered the 2.5 Iron Duke a “decent” engine. The one’s I’ve seen give excellent service were the 2.5’s that got religious oil and coolant changes. To me they sounded like coffee grinders. I had one of these in a 1983 Olds Omega with a 4 speed manual transmission!

[@markschommer7407]

Mom and Dad had a 1992 and my sister had a 1987 and Dad said they sounded like coffee grinders.

[@BrainDamageBBQ]

Pontiac Fiero 2M4 SE 5-speed here. I'll never forget when people would get into my car for the first time and start up the Iron Duke - the vibration from the back! In some ways, I think it was a great choice given the Fiero's complex cooling system. The iron block and head were very forgiving for overheating. The Achilles heel was Fiero drivers made the mistake of over-revving them. I did tear it apart and rebuild the engine, put another 200,000 km on it after that. I miss my Fiero, and I would only want an Iron Duke in it.

[@mrhunt231]

Just bought a 15k mi iron duke fiero, any advice for a refresh? Parts and the like I should do before I try to drive it

[@andrewdonohue1853]

i also had 3 different cars with 2.2 TBI engines and they ran a little smoother and didnt have the timing gear clatter sound..... but they were well known for head gasket issues. given a choice i would rather have the cast iron head sitting on the cast iron block. rarely did they have a head gasket issue.

[@katiewebster9190]

“Crude, rude, and noisy” is WAY to accurate

[@drozcompany4132]

These things sounded like they came with a factory rod knock. Never knew it was the cam gear. They were damn near indestructible though.

[@pcno2832]

At least in '81, they also were designed to ping a little. The owner's manual said that that was normal and that it was due to the engine timing algorithm which maximized fuel economy. It never bothered me.

[@jackdale9831]

WHY didn't the After-market sell an iron/zinc/aluminum timing-gear, so the teeth on the Nylon gear wouldn't potentially "lunch" the whole engine?

[@kevinjohnson5214]

I agree with you a hundred percent , but they were reliable as heck. I know the sound, especially at idle when they were up there in miles..

[@Todd82TA]

I hate to be a stick in the mud, but it wasn't called the "Tech-4" until 1987. Until then, it continued to be called the Iron Duke. Someone added that to Wikipedia, but it's totally wrong, and there's no citation for it. You won't see the "Tech-4" designator until the 1987 model year, and that's when it received DIS ignition, and a serpentine belt with a belt tensioner.

[@dmandman9]

My greatest issue with this engine was the location of the distributor. Combined with the unreliable nature of the ignition module, you had a nightmare when it came to serviceability. It was obviously related to chevy’s inline six. But when they made the cross flow heads, it placed the distributor under the intake well hidden.

[@jimkalfakis9893]

I had one in a boat, an old boat. And it never left me stranded or gave me any trouble, ever. You closed the engine cover and you couldn’t hear the thing run.

[@russelldolter]

I worked in a full service gas station and repair shop during the early 2000's and I never encountered a single 2.5 that did not have a cracked exhaust manifold

[@cbly]

My Fiero had two cracks in the manifold. It used to melt plug wires and shifter cables.

[@spaceghost8995]

I remember people in the 1980's whined at me to "buy American". I said no thank you I like my Datsuns and Hondas very much. I don't even know which was worse in the late 70's or 80's, Chrysler, GM or Ford. They were all just junk.

[@davewallace8219]

True!

[@KevinWindsor1971]

The Grumman LLV had the 2.5l from 1987-1992. The last 2 years (1993-1994) was a Chevy 2.2l. The 2.5l had the catalytic converter right under the driver's feet. The 2.2l had it under the tray side. These vehicles have no insulation against the heat coming up through the floor. The 7 digit truck number denotes the year it was made. The first digit is the last digit of the year.

[@Paramount531]

I'm amazed that they are still in use. I recently moved to Idaho, some of the postal delivery vehicles up here are Mercedes Metris vans with right hand drive. Rural carriers have imported right hand drive micro vans from Japan.

[@TheBrokenLife]

@@Paramount531 My postal carrier is driving one that has to be from the 80s. It's the most beat up mail truck I've ever seen. Apparently they're wringing every last penny out of them that they can.

[@dantheman1998]

I'm driving these LLVs right now. There miserable to be in. But they serve there function well. There so industrial that simple human comforts are none existent.

[@Red84GT]

I had a 91 Buick skylark with the 2.5. The darn thing was damn near bulletproof. Like a Timex watch it took a licking and kept on ticking.

[@drippinglass]

My Dad got a new in April 1979 Chevy Citation. It had that 2.5 4 cylinder and an automatic. I remember the V6 60 degree had a lot more teething problems.

[@homebuilthappiness2919]

I just picked up a skylark with a tech 4. Parked in a field and hadn't ran in 13 years. Hooked a boat tank up to it and surprisingly it cranked right up. Crude is the perfect word for this engine. I remember always knowing when the mail was being delivered because of the distinct sound of the LLV duke and this sounds exactly like it. Almost reminds me of a little diesel at idle and the vibration is almost mistaken for a misfire. It was a free car (with title). I look forward to putting around our property in it.

[@tedunguent156]

I had one of those for a while and I really liked it. I bought a 10 year old 1989 coupe from a little old lady. Ran great and got terrific fuel mileage.

[@mikee2923]

I took my drivers test in my mom’s 79 Pontiac Sunbird coupe equipped with the Iron Duke. I drove it a lot before I bought my first car. We never really had any issues with it. It certainly wasn’t a fast car but thought it ran pretty good for what it was. I remember it was carbureted version. The carb looked like a quadrajet cut in half. It ran about as good as an 81 Grand Prix I test drove that had the Buick 3.8 V6. You can make fun of their low power output but GM made plenty of performance parts for the Iron Duke. Back in the day it was the 4 cylinder of choice for racing. I do remember a buddy of mine had an 82 Firebird with the Iron Duke with a 4 speed manual. It was pretty pathetic. A car that looked that good being painfully slow.

[@crankychris2]

We used to call '82 Firebirds "Emily Post polite", floor the accelerator and watch everyone else go first.

[@falcorthewonderdog2758]

The iron duke was a cheap reliable 4 cylinder power plant in a time of fwd cars and CAFE fuel restrictions. It was nothing special but was very reliable for what it was.

[@neilcook4710]

If you grew up in the 80's like me, you have definitely either owned a car that had one or at least driven one.

[@nikmwh]

As a GM retiree it always surprised me that the company didn’t embrace overhead cam and alloy engine components much earlier than they did; in the UK we made the overhead cam slant four from 1967 to 1979 which was available from 1.6 up to 2.3litres but could be taken up to 2.6 litres; the engine was smooth running and a good all rounder and was successful in motorsport thanks in part to being very oversquare; Pontiac also made an overhead cam six for a few years too.

[@michaelbenardo5695]

GM tried aluminum engines before, but they were nothing but trouble, and tried OHC on the 60s Pontiac 6. That engine was a good performer for a 6 cyl, but was expensive to manufacture.

[@michaelmurphy6869]

Adam, I wouldn't put that engine in the "worst " category. Crude yes, unrefined definitely, reliable absolutely. Power was an after thought. Early carb models were to say the least gutless wonders, when you floored it all it did was make noise and go nowhere... fast. When they TBI 'd them really kinda of liven them up...Some... Always thought of that engine as GM's way of entering into that era of more fuel efficient, compact car powerplants. The oil embargoes of the 70`s (who remembers when gas prices hit a $1 a gallon in around '78 and people were so shocked) definitely caused a shift in the market, which not only GM but all the domestic manufacturers had to adapt. Just about killed Chrysler. Asian cars along some European cars were taking over. I used to call them the "silicone engines" because of the wide use of GMS. They were oil leakers too.. Like you and many others have said it was used in about everything, cars,pickups, industrial and marine, etc applications. Even other manufacturers used them as well. Probably because of unrefinement and crudness they were cheap to produce. The fiber cam gears were suppose to quiet them down a little, in which they did... for a time, but when they started to wear you knew it. They got loud. There was and still probably available aftermarket steel or aluminum replacements. If the owners had kept up on the routine maintenance, (like any car) oil changes, coolant flushes, etc they were very reliable in which didn't see as many mechanical failures. I think because of the lower power output is one of reasons why that could last so long well over 100K+. They were pretty well build inside, besides the cam gear. Never saw (at least in my area) allot of bottom end failures, mostly the typical issues, oil leaks, cam gears, head gaskets ( mostly due to head bolts breaking on the exhaust side usually between cyl's 2,3.) and occasionally cylinder heads would crack due to severe overheating, because of prolonged coolant leak or sudden loss, stuck closed thermostat, etc. They serviced there propose for the time, very well. The much earlier GM 152 4cyl used in the 60's Chevy ll and Nova models was a great little engine, it to was used in various applications. The ones I remember were mostly in industrial use, portable High volume air compressors, mobile generators and even some smaller forklifts. My work has a Daewoo forklift (made in South Korea) which has that engine, of course propane powered, electronic ignition (Hitachi equipped) it runs great. Makes me wonder if GM had sold off the plans/ tooling to make that engine to Daewoo, I know they were "in bed" together for a while, but that's another story. Thank you Adam for the great video and look forward to seeing more.

[@richardprice5978]

every worked on a ford T-engine? as im 🤔 thinking it might be cousin's to it as later t's had OHV head casting or at least a option to fit one and the big 3 at one time used the same sub supplyer of engine parts ect.

[@michaelmurphy6869]

@@richardprice5978 No I haven't, to be honest I've never heard of one. Is it the Ford 4 cylinder flathead model T engine? Those engines were also used in many industrial applications, very durable and dependable. What I was told, many are still in use around the world and replacement parts are still available. It doesn't surprise me that the big 3 auto makers shared part suppliers, possibly one way to keep overall costs down.

[@richardprice5978]

@@michaelmurphy6869 yes the flathead L-4 ( and i think grow to 4->L-6 -> L-8 cylinder's but by 1970 8 died off ) that i think 🤔after being tipped off got to live on intel at least the 1990's but by that point it was changing to meet the automotive manufacturers needs in the marketplace. and it wouldn't surprise me if there's a AL castings version of it or twin cam ect. letting live on aka the 2009 dura tech boosted chevy cobalt engine/goblin engine ect. . i will say if thats the case gm tried to do a better job than jeep 4.0L 6 or 4cy as it got stuck in the past and is easier to see the history back the 1930's 😉ect. plus the paperwork trail i just don't have the paperwork/evidence showing that but yes covertly sharing a base model engine and or transmission ect. would cut down on costs a lot, and contental is my first pick to look for the laundry 😉 and at one point sounded like they were bragging about being a automotive car manufacturer but never one with there logo on it aka hit i think 💭

[@richardprice5978]

@@michaelmurphy6869 yep sharing does let you have marketing choices and let you do expensive orders sheet options like a 426 hemi that dodge knew might not be a great seller but does help the overall brand image ect. same for caddilaic car's as a hole for gm pre-1985 as the 1970's was probably the last of the real competition for rolls or miboch ect and now days isn't even in the same category of car sad 😞

[@ladamyre1]

I worked at a Chevrolet dealership in the 90's and we used to get a "gravy lick" when a customer would complain of timing gear noise. 4-6 hours warranty time to R&R the camshaft on trucks and 14+ hours on FWD cars so the cam gear could be pressed off and a new one pressed on. Fact is we could chisel off the gear and press on a new one by drilling a hole in the cam, cutting fine threads in it and using a bolt and washer to screw it down on the cam. Durability? Well look at those Grumman post office trucks (they're on S10 chassis) STILL running around the neighborhood. Some of those are over 40 years old and still running the original 2.5L Iron Dukes, some of those with enough miles to go to the moon and back... TWICE!

[@elvenwizard12]

Before I see this I will comment. I run the iron duke engines in my Fiero’s as a daily driver. These are the most simple reliable engines I have ever had. The simplicity is unreal. Take care of the engine don’t go crazy on it and it will provide many years of reliable driving.

[@RareClassicCars]

I agree. I mention they’re reliable. They’re just very, very unrefined

[@phildavis3105]

Probably should have watched first. Several of my friends had this in their cars. Very reliable but also unpleasant.

[@kevinbarry71]

A very backhanded compliment. Don't go crazy on an engine that hardly had any power to start with. In a car that was pretending to be a sports car. Not sure I understand the point of that set up

[@christopherweise438]

@@kevinbarry71 - The Fiero was only meant to look fast.

[@elvenwizard12]

@@kevinbarry71 There is enough videos of teenagers blowing up this engine by over rev ing it. What I meant was take care of the engine and know it’s limits.

[@davidroberts3692]

We had a brand new 85 Celebrity station wagon with this engine. It would haul 7 people around(although not a ball of fie) quite well. Drove the car for ten years and never a hiccup!

[@Infinitrium]

An Iron Duke will run like poo longer than a lot of newer engines will run, period

[@donaldhollums3278]

I hated changing the oil on that Iron Duke in the GM A-bodies, that stupid element filter installed right into the bottom of the oil pan; what a mess!

[@irey1978]

My dad had a 1989 S10 with the 2.5L and it was a good runner. Had two issues heater core blew and the computer went out. We went on many road trips. This truck with a 5 speed would get 30 mpg. Hit the hills in 4th gear and run 65 mph over them. I do remember those 2.5l in GM cars and boy talk about rough.....yikes.

[@RareClassicCars]

Yes. It’s funny. All the S10 guys are upset w me, but this engine in an auto trans fwd passenger car was really a disaster.

[@garylangley4502]

One of the worst engines? I really would not put it in that category, but you don't have a "Most Mediocre" category, which is where I would put it. I had an '84 Chevy Citation with one, and I was quite satisfied with it. It was reasonably easy to repair, with the noticeable exception of the distributer. I specifically looked for one with the throttle body injection. The computer controlled carburetors of the era were just a pain. The manufacturers were beating a dead horse trying to make a carburetor work under those conditions, and even throttle body fuel injection was a huge improvement. From what I have read, the S-10 and Long Life Vehicle had a beefier block and so on and the LLV postal trucks live up to their name. The last ones were made in 1998 and they are mostly driven in terrible conditions of short stop and go runs, but they are still running.

[@jas4925]

Had 2 celebrity's in high school and college. A 1984 and a 1989. Both cars had around 120,000 miles when I got them took them both past 200,000. I will say the 89 was much more refined than the 84 was.

[@crankychris2]

I think they got balance shafts in '87/'88 depending on the tranny.

[@EVnewbie]

Worst engine? Well, I had one with a 4 speed stick and my buddy had an S10 with a 5-speed stick and we both beat the snot out of the things--they would not die. After years of abuse, I sold the car to a buddy that pulled the Duke and put it in a swamp boat. The thing did not burn oil, leak oil, did not leave me stranded and sure, it was rough, loud and socially unacceptable but it matched me. Hmmm, might have done a few "adjustments" to the carb, put a louder muffler, flipped the air cleaner cover and played with the timing to wake it up a bit (cough, cough) It's legal as long as you don't get caught and no sniffers ever violated my tail pipe so no worries. Compared to most of the garbage plying the roadways, the Iron Duke just plugged along. Changing the starter sucked...I did change the distributor cap, new larger radiator and the biggest battery I could cram in when the alternator needed replacement but not bad. To me, worst engine means that the thing is always breaking down--never had that problem. It was a shaker but so was the Toyota 2.4L of the early 80's...as long as you kept the tensioner on that engine stable, it was a good engine also. Never delt with a Duke with a sluch box though, you needed a stick back then if you cared anything about performance so that is what we ran. I'd rather have a shaker that just ran than a smooth engine the leaks oil, coolant, breaks cam belts, eats cams and dies just as the payements end.

[@burtvincent1278]

I'm pretty much a Ford man but the Iron Duke and 4.3 V6 have served me well.

[@5610winston]

The Iron Duke has a lot in common with the early Chevy II and the original Tempest 194. That is not a compliment.

[@user-cs1ne8gx9u]

You could do a lot worse than the Pontiac 151. It was probably the best gm 4 cylinder up until maybe recently.

[@RareClassicCars]

Precisely the problem.

[@user-cs1ne8gx9u]

@@RareClassicCars other than antique stuff gm didn't really have many bangers of there own design. The old cut down Chevy 153 was a heavy turd but reliable. Then the duke, and the olds quad 4 that wasn't very good, and the j platform engine that evolved into the ecotec that was never very good either. Everything else was mostly Opel gm, Suzuki, Saab, Daewoo, Isuzu stuff. Really now that I'm thinking of all the crappy small/compact cars gm has put out that may make an interesting video if you haven't already. I'd say the last good small car gm made would probably be the rear wheel drive x platform with the Chevy or Buick 6. I like the porch talk, and most of what you've got to say I'm in agreement with. Thanks.

[@mph5896]

A similar engine, the 2.0l and later the 2.2l in the J body's were fairly stout. My family had a mid 80's Cavalier back in the day that would not die. The powertrain was solid as can be. The body got crusty and was replaced. My brother then delivered pizzas with it for years before selling to for a few hundred dollars. New owner drove it for a few more years (and never titling it) and abandoned the car on the side of the road.

[@user-cs1ne8gx9u]

@@mph5896 sounds like a Chrysler lh 2.7 I've got that just won't quit. The car has 302000 some odd on it now, even though they are rightfully regarded as junk. My daughter loves the car though.

[@michaelbenardo5695]

@@RareClassicCars Better than those foreign engines.

[@dr.jekyell9089]

As a mechanic for 35 years, my experience with the Iron duke engine, proved to me the duke was Very Reliable.

[@johnmcmullen456]

An old school, reliable engine, plenty good enough for its day. Was used successfully in many applications, including some CJ Jeeps and inboard/outboard boats. Better low end power than overhead cam 4 cylinders.

[@fleetwin1]

Yeah, those old Chevy four cylinders did surprisingly well when used for a stern drive engine in a boat, even in salt water. But, I don't think these were the same engines as the "iron dukes".

[@michaelbenardo5695]

@@fleetwin1 The bore and stroke was a little different, but yes, they were pretty much the same until the cross-flow head debuted on them.

[@fleetwin1]

@@michaelbenardo5695 Yeah, those old 4 cylinders really took a beating in boats, and were amazingly reliable, even in salt water

[@michaelbenardo5695]

@@fleetwin1 People were thrilled when it replaced the horrible Vega engine.

[@fleetwin1]

@@michaelbenardo5695 I'm sure dealers and customers were happy. But, it seems like GM had probably already lost customers that had suffered with the Vega engine

[@kramnull8962]

I bought a 1992 S10 in '99 for $500. The owner was an old man that had altimeters, overheated the 2.5L 4Tech. The head was found to be cracked at least 17 times. Turns out it wasn't his fault. I found that from the time I bought it, the water temp gauge on the factory instrument panel was locked to normal temp. Even when it was cold. So he didn't really know most likely, at his age at least. Took the engine apart and rebuilt it. Great engine, doesn't use any oil and fairly good gas mileage. Downside, it feels like it has a permanent vacuum leak with little to no power. I had to change the valve springs; cooked. The rocker arms; cooked and pushrods. Naturally a cam and lifters were in order. I should have decked the block and head surface area just for a good flat surface, but you can only gold plate a 90Hp engine so far....

[@aceuser656]

I think there was a marine version used in stern drive boats and I think I saw an industrial version recently on a standby backup generator.

[@crankychris2]

Correct, matched up to a Volvo-Penta outdrive they made 120 hp. The only 'car' engine I've seen in commercial gensets was a Ford 300 I6 which has 7 main bearings. It made 87 KW continuously, 92 KW wheen tuned for LP/Natural Gas. A commercial version of the 151 would probably make about 60-70 KW at 3600 rpm.

[@James_Hough]

I sold S-10s on a used car lot in the early '90s. GM trucks were our specialty. The only S-10s that I saw over 200,000 miles had the Iron Duke. I saw a bunch of them. The would just run and run and run with minimal maintenance.

[@privatedata665]

We repaired many timing chain Dukes . The chain would break at about 80K miles and come out through a hole it created in the timing chain cover ....a lot of them .

[@jamesgeorge4874]

The 2.5 Iron Duke he is talking about all have gear driven cams, so I think you are mistaken.

[@privatedata665]

@@jamesgeorge48741991-92 VIN R and U engines used a timing chain instead which also required a different camshaft . I repaired dozens that broke the chain .

[@michaelbarry8005]

It's 2022 when I post this from central California, and my shop has a contract with the local USPS branch to do the repairs on their trucks they don't want to do internally, like transmissions, flex plates, rear main seals, rack and pinions, etc. We see two types here, the ~30-year-old S-10 based Iron Dukes and the ~20-year-old Ranger based 4.0L OHC V-6s. I like (and hate) all engines based on merit rather than parent corporation, and I must say that the Iron Duke vehicles are FAR easier to repair and maintain than those crummy Ford V-6 vehicles. The GM units are all significantly older than the Fords, but we see them here in equal numbers, which hints at the relative durability too. The Fords would clearly win a side-by-side drag race, but who cares when you're hauling mail? I have owned and enjoyed (some more than others) several Ford products over the last 38 years ('62 Ranchero, '65 Falcon, '78 Fiesta, '79 Zephyr, '82 Mustang, probably a couple more I forgot), but that OHC 4.0L just rubs me the wrong way. I have never owned an Iron Duke, but I can easily identify them by their distinctive coffee grinder sound before I even pop the hoods when they pull into my shop for smog checks, services and repairs.

[@WildBill236]

Owned 2 "A" cars with this engine, although gutless and noisy to the point years ago someone asked if it was diesel, very dependable. Decent fuel mileage, in terms of a TBI engine, and very simple to change almost any control on, in car especially. The early fiber timing gear left us stranded once, but my 88 model with balance shaft and silly "in pan" oil filter sat 2 years in a swamp in the back field, has every wire and contol bypassed, has rodent nests all over, still sounds like it did when new, yes I am saving this engine.

[@jeffbranch8072]

I was acquainted with John Sawruk, who had been the chief engineer of the Iron Duke at PMD. In a presentation to the Pontiac-Oakland Club International he said this was where they really missed the OHC6 (that GM Corporate management forced them to sell off after 1969). They would have loved to develop the Iron Duke as an OHC design from the OHC6.