GM 2.5L Iron Duke Valve Adjustment

If you have valve noise due to a failed lifter you can get a cool tool to pull them out from Amazon here →www.amazon.com/gp/product/B001... With this tool you can pull them up and out without having to pull your ignition coil, distributor etc. Great way to inspect or test them without major tear down!
GM 2.5L Iron Duke Valve Adjustment Chevrolet Opala

[@mschiffel1]

This is an early Iron Duke with both manifolds on the same side...later Dukes had a crossflow head...this engine in your video is very similar to my 1965 Chevy ll non- Iron Duke 2.5L inline four banger, which is 153 cubic inches, rather than the Iron Dukes 151 cubic inches...often, people get these two different engines confused...this is a great video and you did a fantastic job...keep the "how to " videos coming !

[@bborkzilla]

I have a 1988 S10 with that engine. It's not the best engine ever made, but it keeps running!

[@reso1349]

Great little motor the 2.5L Iron Duke, along with the Buick 3800 V6.

[@trancus11]

especially with a blower on that 3.8L V-6. What? Who said that?

[@roterakaten636]

Couldn't agree more.

[@rhkips]

The Iron Duke is also the engine inside the Grumman LLV that the USPS uses for residential deliveries. Bulletproof little monster. :-D

[@ldm125]

I have one. It's too stupid to die. When I bought the truck 10 years ago, I said "I'll just put a v8 in it when the 2.5 dies..." aaaand 10 years later it still runs. Oh well. Someday.

[@chrisgosselin6399]

My guy that opening song should be the door chime on every duke equipped vehicle

[@trevorbentz3888]

fits beautifully in my willys cj2a, love the power

[@unho1ywoodca1ifornication77]

I had a boat that had two of these in it, they're real good engines

[@urgentcareguy3]

I had an iron duke in a company car. One time a guy said "hey I didn't know they put diesels in those" LOL it was the valve train.

[@johnscreekmark]

I’ve got one of these in my ‘88 S10. Runs like a tank.

[@jewllake]

love your videos and the careful through explanations you give. We had an old 86 Grand Am with that 2.5. Very sturdy motor you can beat them to death and they keep on going. They are noisy by nature due to the timing gear drive they have.

[@AdirondackNY]

it looks like a fresh rebuild, i remember putting new lifters in an oil bath and pushing on them with a push rod to bleed them before installing them.

[@MuddyDrivewayProductions]

Thumbs up just for the intro! Wish I had more to give.

[@wadesmith7041]

Thanks for the great information on the Iron Duke👍

[@patsmith6506]

Hi, I'm older than dirt, back in the start of this type of rocker we used to pull rocker cover lay shop rags on the rockers to catch spatter, start engine at idle, SLOWLY LOOSEN till cylinder skips, then retighten 3/4-7/8 turn moving rags to access each rocker (this is for an engine already running not a new build)

[@jrmym2]

@Milford Civic Each nut sits on top of a semi-spherical bearing, the rockers pivot on said bearings while the nuts remain stationary.

[@Westy73]

My Dad had an '85 Celebrity Wagon with a 4spd manual and a bench seat, (weird combo for sure) - this vid reminds me of when we did the top end around '92.

[@squarebodychevyoverhauls6982]

I'm sure all of you know this already, but this engine is the chevy built 153 cu in engine , other wise known as the stove bolt 4. It was designed after the 240 in line 6 and was shortened into a 4 cyl. Production period was 62 - 70 . If you google Iron Duke the 151 cu in pontiac engine comes up. It's a completely different engine. It has a cross flow head and you don't need to adjust the valve lash. You just bottom down the nut and torque to spec. So people don't be confused by the name Iron Duke that it's production period was 77 - 93……………..

[@shitbox7413]

Yep this engine is not an iron duke. 👍🏻

[@bobcat1]

I am confused by what you are saying in last sentence. Was the iron duke produced between 77-93 and it is a 151 pontiac engine?

[@leesire]

bobpuddyy is the 120 hp mercruiser built in 1986 an iron duke? I think mine is that. In a 1986 Thunder Craft boat

[@squarebodychevyoverhauls6982]

@@bobcat1 I didn't see your comment . Sorry about that . Yes you are correct. The engine in this video is a Chevy engine. Not the 4 Tech Iron Duke Pontiac engine

[@squarebodychevyoverhauls6982]

@@leesire Yes you have the Mercruiser Marine engine. Not to be confused by the Iron Duke installed in lots of GM cars and trucks

[@AZdirtdog]

Same procedure on all the early chevy motors, you can by the plastic plugs that clip onto the rocker arm when adjusting when motor is running. With motor running you loosing till it taps tighten just enough to stop the tap then go 3/4 turn and a little love call it good, you can do a v8 in 3 min with the covers off

[@klc317]

Our boat has the same engine. Sure are reliable and tough and never fails to fire up on 1-2 cranks.

[@BenBuckner]

Sounds smooth!

[@garrythompson475]

They make a little clip on cover that redirects the oil while you adjust the valves with the engine running

[@robplotts9412]

Its a hydraulic lifted engine! Crank the rocker down till the looseness in rocker is gone back off a half turn done. Of course make sure valves are shut completely first. To hear a valve train not loud but hear it is good if you dont hear it something is too tight

[@RobsPackanShine]

nice vid...nice tip on turning the motor

[@frankcatalano7368]

2 hints: 1. remove your spark plugs or at least loosen them and the motor will turn over more easily, this is on any engine. 2. On the FWD 2.5's like used int he Fiero these are not studs. these use a shoulder bolt instead, you can acquire .437 ID shims and carfully "shim" the rocker down. The shim would go between the head of the bolt and the ball the rocker rides on.

[@copykon]

First car was an 84 camaro with an iron duke - manual trans. Got decent mileage but top speed was around 70 mph unless going down a hill.

[@nathandube1685]

oof thats painful, i have an 88 fiero with the iron duke. top speed is 85 cause thats where the speedo stops hahah! If the Officer ever asks I was only doing 85.... Blue could follows me wherever I go. time to change the valve seals.

[@mikeodinson5665]

Getting ready to do mine , when adj lash is there alot of side play ? I have an 83 omc 2.5 all original, love these little dukes , solid motors , other than a new rochester 2bbl never had to do anything to mine .

[@guymanicone7921]

I think this is the chevy marine 153ci, not the Pontiac 151 that was in the Fiero's, small trucks and so forth. My spark plugs are on the opposite side

[@shawngoodell772]

You are correct the the iron duke was a 151cid 2.5l pontiac and the this is a Chevrolet 2.5L 153cid. About the only thing they have in common is the bell house bolt pattern.

[@PearComputingDevices]

I had a 1984 Olds Cutlass Cia wagon with one of these. Not exactly powerful, but my goodness nearly bullet proof and very good on gas. I think I got after the rebuild about 16 miles per gallon even in the city. But, that engine would just go forever. The only reason I sold it was the car body, the engine outlived it.

[@chrispesta4068]

Great video but whats the starting fliud at the end for I use it at the beginning

[@KnuckleHeadGarage27]

Wounder if this be same to do for 88 s10 2.54cyl. I found one of rocker arms off and the bolt backed way off so guess it got loose by it self ? Just wanna get it tighted back down cause truck runs like crap

[@Lazyman1975]

Love this little engine. Motors are electric lol... Only thing I don't like is a spring and plastic button up against the timing cover to keep the cam from floating... Caused the infamous 2.5 tick...

[@garrythompson475]

If you want to get real precise use a dial indicator, watch where it stops at the top. then run it to the bottom until it stops. Split the difference and adjust accordingly

[@str8uponitsolo152]

Best video on this yet by far thanks and isnt the iron duke the same as the mercruser 3.0 140

[@marshasmith9531]

Great video

[@trevorbentz3888]

I love this motor

[@ltkaffey]

Hey brian, If you had to do the adjustment running, you could use "rocker stoppers" to stop the oil splashing everywhere.

[@bblackdogg4352]

Or use an old valve cover with the center top cut out the entire length.

[@jarrettfrangel1069]

briansmobile1 how would you take off the 4x4 linkage in a 1992 ford f-150 5.8l ext cab truck?

[@TheTech660]

Cool Vid! Thanks!

[@scottgeorge4760]

I got the 1985 IRON DUKE and. rebuilt the head and put roller rockers in it in place of the old non roller rockers , and a new stock 😦cam , I should of put in one out of a FIERO 😀. I own an S-15 GMC JIMMY and its 4 wheel drive , 5 speed. I did my timing gears and starts , fuel pump , all kinds of stuff and I still have it . Needs brakes and rotors .

[@crimsonfilliu]

How many miles are on these? I have an iron Duke with 301,000

[@JimG-kn6eh]

The Iron Duke engine (also called 151, 2500, Pontiac 2.5, and Tech IV) is a 151 cu in (2.5 L) straight-4 piston engine built by the Pontiac Motor Division of General Motors from 1977 until 1993. But the engine that Mercruiser used (in boats) was a Chevy 153 (not 1) engine. Both are 2.5 liter. But the Iron Duke is Pontiac (not the Chevy one). There may be very slight differences but the boat motor is not the "Iron Duke". But it seems that everyone thinks it is. I don't know what the differences are between the Chevy 153 and the Pontiac 151 (Iron Duke).

[@NoAfilliations]

Thanks

[@elmerhart9430]

I have a 1985 2.5 151 engine installed new lifters I still have a loud tappet noise at a idle no adjustment on valve tappets what can you do when you can't adjust

[@jerjoer1]

I noticed you didn't have lifter guides installed. Are they not necessary? If so, for the love of god, where can I get new ones?

[@D6Spanky]

Nice.

[@mrjb1445]

What year vehicle was this engine out of? because I have a 1992 Buick Century and it might need the valves adjusted and or rocker arms. I too have the 2.5L Iron Duke in it.

[@turbofiero86]

my 86 fiero has one of these engines... and after sitting for a decade i got it running and it seems to tick at an idle (or can only hear it at an idle) very quiet though, and very fast... any ideas? im aware they're noisy engines, but im looking for some reassurance as this is the first duke ive got my hands dirty with. Edit: with the hood open, it seems to be louder, with the hood closed, you pretty much cant hear it

[@leesire]

Is this the same as a 120 hp mercruiser 87ish

[@lloydspooner]

Do you need to run the engine first or can this be done cold?

[@milfordcivic6755]

So, the nuts holding the rocker arms on have no lock on them? How do they not come loose?

[@aldodonovan7427]

that is the original thermostat housing in your iron duke ?

[@user-gs6tg2yf5d]

Great job I have this motor in boat, the cam shaft gear striped the distributor gear. The crank shaft gear has a good timing mark, but the old cam shaft gear and the new cam shaft gear have no timing mark. How can I get the crankshaft and camshaft back in timing

[@briansmobile1]

Watch the #1 cylinder to be at the top of it's compression stroke, and line up the intake and exhaust valves via the cam rotation to be closed on the #1 cylinder on the compression stroke. (between squeeze & bang of suck, squeeze, bang, blow) Paint a mark on the new distributor metal where the #1 spark plug wire goes on the dist. cap. When you put the distributor in with the rotor on and the dist. cap off, the rotor should be pointing at the #1 paint mark you made or close to it. The cam rotates 1 time for every 2 times the crank does. If it runs terrible, you're off by 180° on the cam/distributor so you'd have to have the cam upside down from how it was. (that's if you have confusion about the intake & exhaust valves closed on the top of compression stroke cyl. #1)

[@luiscaro1338]

Thank you for your video.It help me a lot.

[@TuzonaAracno]

hello could you tell me the location of the VIN code block

[@noobydiablo]

The need for a valve adjustment often means the cam is close to death

[@sanshism]

this engine is used in the chevy opala, the ''brazilian muscle car''.

[@sanshism]

I am preparing my motor "iron duke" to "track day". not find much information. I have four opala chevy here in Brazil

[@edwardmetcalf9189]

my ran out of oil once drove over 20 miles it was red hot when i got to destination. let it cool down added oil it ran perfectly still. lol

[@dylancamp5602]

I’m looking for a block if anyone knows where I can find one would be great

[@amunderdog]

That would have been easier to turn thru with the spark plugs removed

[@RobertGSolomon]

I was just going to say that because any time I do this the plugs are out, make you wonder.

[@jasonmarek1022]

my 1980 jeep cj7 has the gm151 (iron duke) However the rocker nuts are not locking. setting the pre-load to 3/4 turns does not work. the nuts are basically hand tight. as soon as the engine runs, the nuts start to loosen. after a lot of reading, my gm151 needs the rocker nuts torqued to 20 foot pounds.

[@ChrisHplusland]

I'm into this right now with a 78 Monza 2.5 The engine has non adjustable rockers with non locking nuts that are meant to be bottomed out and torqued down.

[@mschiffel1]

I just subscribed.

[@daryllynhutchins8459]

We have a cut down 6cyl gm in Australia called the starfire4 put in aus holdens and Toyotas not much chop as an engine

[@JohnDoe-ml8ru]

Nice, but you can not properly adjust an adjustable valve train with the engine off. You have to have the engine running so the lifters are pumped up. The only thing you can do is perform an initial adjustment before startup, but it will have to be adjusted again once the engine is running.

[@richardkaltenbach3961]

1977-1980 Chevy MONZA, Pontiac SUNBIRD, And Oldsmobile STARFIRE Also.

[@briansmobile1]

+Richard Kaltenbach You know your Iron Duke!

[@regularfella]

+briansmobile1 I have one in my 1989 Chevy S-10, too.

[@NeilCaulfield]

What size pushrods does this engine use in the 1988 s10 variant? I ordered a set of 16 that were supposedly the correct length, which would have given me two sets. They are the right diameter but about a CM short. I have one bent rod that I probably bent in the process of doing some head work on it.

[@briansmobile1]

Neil Caulfield I wish I could tell you, but a cm is a lot to make up for in adjustment.

[@ryanchastain6133]

This looks nothing like my iron duke What year is it?

[@johnchristopherson2718]

My 10th great grand mother Sarah Wildes was executed at the Salem witch trials. Have you replaced the timing gears on one of these engines?

[@scottgeorge4760]

I did 😀 ! , their is two gears and no chain . I got some plastic/ nylon gears originally and got some cheap"O" aftermarket ones when mine broke .

[@joshn215]

That's why it's always good to have some cheap Chinese sockets u don't care about to weld on custom brackets

[@freshsaltyfries5078]

Thanks for the video. I have 3.0L mercrusier on 17ft boat I bought the boat found milky engine oil. Removed heads no blown head gasket and found broken impeller on the water pump. The engine did run. Now I need to learn how to adjust the lash and timing the engine. Never worked on car engine or boat engine. Im good with tools. Any tips would help.

[@Mrcaffinebean]

What ended up being the source of your oil? I have the same issue and am thinking it’s the head gasket.

[@freshsaltyfries5078]

@@Mrcaffinebean after replacing all gaskets and parts found the gasket was broken at exhaust Intake manifold. After watching your adjustment lash my engine running smooth no clatter took it to the lake she ran great 👍 thanks for sharing.

[@briansmobile1]

Glad it helped

[@desertfox2020]

I have an 05 Grand Prix Comp G with the 3800 S/C engine with what sounds like a noisy valvetrain that I can hear under acceleration, but not when the car is out of gear. It begins around 2000 rpm and lasts until the supercharger whine drowns it out about 3500 rpm. I've heard people guess at it being anything from a worn timing chain slapping around to a loose rocker. I just can't see anything being wrong that would cause this sound that doesn't have an accompanying performance problem. It runs perfectly, except that when you start it, the RPMs don't flare up. It just lazily stutters to life. The sound is most noticeable if, while climbing a hill, you lock it in 4th and floor the gas pedal. The engine will bog a little and then the tapping or rattling or whatever you want to call it is extremely audible. I know this isn't an ideal place to ask questions but I wondered if you had encountered this before. Thanks.

[@stevensapyak7971]

6.29.14. Sounds like a case of spark knock. Your engine calls for premium gas. What's the mileage on it? Also an EGR problem can give you trouble.

[@desertfox2020]

Steven Sapyak About to hit 89k. I've owned the car since 75k and it's been making the noise the whole time. I always use 93 octane, I understand boosted engines and I know the 3800 pretty well. I also know what spark knock sounds like and this isn't it. I should've clarified that the sound becomes more audible because then the engine isn't building any boost, so the supercharger doesn't whine much and you are able to hear other things. I have a short ram intake and a Borla exhaust so it's a fairly loud car in that rev range anyway. The sound however is pretty quiet, you have to turn the radio off to hear it at all 90% of the time anyway. Thanks for the reply.

[@DENicholsAutoBravado]

It's sounds like a valve job to me. Tough to say when my imagination is going off of words. Take a recording of it with your phone or if you have better and post up a youtube video, we could help better then. :)

[@desertfox2020]

DE Nichols I've tried, but it just doesn't pick up the sound on video.

[@DENicholsAutoBravado]

Kudos for trying. I haven't had the courage to try towards putting anything on KZbin. Maybe a baby step would be to at least take pictures of my mods and put them on my website.

[@pauloeduardo9604]

The Brazilian Chevrolet Opala use that engine.

[@briansmobile1]

Good to know! Thanks!

[@MLFranklin]

What year is this? Is it an early Iron Duke or... It looks a bit like the (non-interchangeable) Mercruiser 3.0 140.

[@briansmobile1]

It's out of an early 1990's boat.

[@moonmission]

Trying to find more info on this engine (marine version ) can you possible direct me ?

[@briansmobile1]

This is the marine version.

[@shawngoodell772]

That engine is NOT an Iron Duke. The iron duke is/was a 151 cid 2.5L Pontiac. That engine is also a 2.5L but is not a 151cid but is a 153cid Chevrolet and had between 120-140hp depending on the tune. That particular engine is a mercruiser model.

[@jessepolka]

This must be an 'early' iron duke engine. It doesn't have a 'flow through' head. Mine is 1987 with flow through in a 1987 GMC S 15. Great lesson on valve adjusting. Thanks.

[@henrymccarty8014]

Guys my 88 s10 started to throw smoke out of the engine bay y is this happening it smells funny wen it does??

[@johnheaserjr]

it goes exhaust intake exhaust intake intake exhaust intake exhaust

[@leobarajas81]

does this apply to hydraulic lifters??

[@scdevon]

These are hydraulic lifters in this video. Even hydraulic lifters need an initial setting like this for proper operation.

[@angelrodriguez6590]

I am looking to rebuild my 151 cu, 2.5 iron duke

[@leesire]

Angel Rodriguez did you rebuild it?

[@stefanwindhorst-of2nd]

151 cubic inch

[@NoName-ck2cq]

The 2.5 Mercruiser is not a Iron Duke. The Iron Duke is a 151 CID 4 cylinder manufactured by Pontiac

[@DavidAmmerlaan]

runs like new again

[@dougyoung221]

Hmmm, my iron duke has shoulder on the rocker bolts. Tighten to shoulder then torque to specs. No adjustment, its all on the hydraulic lifters.

[@leesire]

I have a 120 hp mercruiser in my 1987 thunder craft engine. How do you know if it’s the iron duke?

[@hellenanightshade2]

do you have a website,phone#

[@thebug4046]

the amc 2.5l is a iron duke to!

[@playsportfun3356]

So just like a small block

[@anthonyfili11]

I always thought that you didn't have to adjust hydraulic lifters

[@briansmobile1]

Technically this is adjusting the rockers.

[@kurgan322]

I say this with the utmost respect. Technically, you are setting the lash and pre-load on the hydraulic lifters.

[@frdradio]

WWII Planes... Ever play War Thunder, Brian?

[@yeaung5384]

6:18 the engine is crack

[@danawick9817]

Hmm my 84 has a bolt

[@walterhoward5686]

This engine is not an iron Duke !!!!!!! What is wrong with you people !

[@briansmobile1]

Not every adhesive bandage is a Band Aid, but people still call them that. This is from a boat and is newer.

[@sidvicious7813]

Um, that is NOT an Iron Duke. This the Chevy version which is called a STOVE BOLT. The Pontiac version - which is a 2.5 is called the "Iron Duke". This engine is a Mercruiser 131 or 181.

[@darylsargent8099]

Sid Vicious ya iron duke engines have cross flow heads This is one of those hacked up chev stove bolt six engines shake head mechanic

[@bblackdogg4352]

CORRECT! Or a Volvo Penta 3.0

[@leesire]

Hey, are you still around?

[@leesire]

Guess ur history?

[@MLFranklin]

Not an Iron Duke. Bore spacing is the same, but almost no interchangeable parts.

[@maddenmadness]

HP???

[@StoneCanyonCreatives]

Like 85hp if you’re lucky lol. But in my Oldsmobile Calais with a 5 speed Manual I get 31 mpg highway and city. It’s a engine for reliability and mpg. But people have built these things up and I’ve seen people on forums say they’ve pushed 185hp

[@x2xplaguex2x]

First post!

[@kyleranderson1948]

NOT an Iron Duke. This is a 153cu in Chevy

[@briansmobile1]

It's from a boat.

[@kyleranderson1948]

@@briansmobile1 and?

[@JoeyRamone442]

lol i would of just just welded a nut on to the tool rather than wasting a socket and then but the socket over that nut.

[@anthonyrotella6106]

That's not an iron duke just an old 4cly from Chevy. The iron duke was Made from 1977 to 1985

[@briansmobile1]

4cly you say?