The 6.5 Detroit Diesel | The Worst GM Engine?

[@kevind3185]

The 6.2 and 6.5 Detroit Diesel is actually a great engine once you get rid of all the bullshit GM Engineers did to it.. it's used in many applications that reliability is the number one concern such as military and marine use

[@8020Media]

Kevin - We absolutely agree!

[@justinpurvis7449]

I’m in the process of that right now. Got a 2000 1 ton that I love. But it does not like weight.

[@Rev1Kev]

Agreed, the 6500 Optimizer from AMG-GEP is the way to go for replacement, better castings, improved cooling and the biggest improvement is a forged crankshaft

[@jdrok5026]

Gm engineered it entirely Detroit was a gm brand at the time.

[@dougapgar7414]

It is a great engine one of the reasons why they used it in the military very reliable fuel mileage is great and the things that go wrong are the most stupid things

[@JMASON-qy7ki]

I find only people that hate these engines all have one thing in common, they have never owned one! I have a 1982 c-10 shortbed with a n/a 6.5 mechanical pump out of a 94 suburban. I drive around getting as much mpg as corolla while looking/sounding badass. The sound of the 6.2/6.5 is one of the best sounding diesels in in opinion.

[@8020Media]

J - We would have to disagree. "They have never owned one," is quite comical. Just because you have had a great experience with it, doesn't mean others haven't. Now can we say that they have maintained it properly, no. However, thanks for taking the time to share your experience.

[@WrenchWhacker]

@@8020MediaNo, they’re completely right. 99% of these goofballs never owned one NOR do they know how to maintain any sort of Truck Engine. If anybody knows their stuff, they know Detroits are good. If Detroits are so bad, why do multiple militaries use them, and TONS of Heavy Equipment still use them?

[@wild1athletics]

I love my '98 K2500 6.5td. Fuel efficient, easy to work on, affordable, and can tow anything I need. I had a hard time diagnosing a bad optical sensor though. Easy fix once I got my hands on a replacement sensor.

[@8020Media]

Central - Love hearing that! Thanks for sharing your experience, it will certainly assist future viewers!

[@wild1athletics]

@@8020Media The codes it threw were P0251 and P0370. Ran poorly and would sometimes be put in limp mode. The optical sensor brought it back to life. It had this issue when I bought it, so I got a pretty good deal on it : )

[@8020Media]

Sweet! Good to hear.

[@koolmotor420]

How did you track down your problem being the optical sensor_?

[@wild1athletics]

@koolmotor420 Part swapping basically. did the clear fuel line trick, lift pump, all filters, etc. Injection pump was Rebuilt with new orings about a year before I bought it so didn't think it was that. They must've used same bad sensor. The sensors are about $300 so hard to justify the cost unless you know for sure. The codes were the telltale sign though. p0370 p0251 I believe

[@ThirteenTwentyRepair]

I’ve been happy with mine, been around a few of them. Quadstar eprom, 4” straight pipe, later cooling upgrade, hx35 putting out 15-22lbs intercooled. Servo delete in the 4L80. 230k currently

[@8020Media]

T - Sounds like you've got a sweet build. Thanks for sharing your experience.

[@daleferber2096]

After replacing my injector pump the first time I learned that there was company in Michigan that made after market PMD modules that you bolted to the intake manifold , they had big heat synch on them. I bought one of them the next time the PMD started failing after about 4 years and it worked fine . I had that truck another 5 or 6 years until I replaced it with an 01 Duramax K2500HD ECLB which I still have today.

[@8020Media]

D - Thanks for sharing your experience. This will certainly help future viewers.

[@nou8257]

A big misconception people have is that this engine was for towing like the 7.3 and the cummins and it wasn't really. Gm had the 454 gas for towing at the time and the 6.5 was the more economical choice of the 2 although even today people are finding ways to amp the 6.5 up.

[@8020Media]

Nou - Thanks for adding this insight.

[@Jean_1999]

Oh really? I feel like the 6.5 always was more of a workhorse engine. I thought the economical choice was the small 4.3 engine

[@nou8257]

@@Jean_1999 between the 350 or the 454 in the lineup the typical engine people would get to pull trailers and just work with it was the economical choice a 6.5 in decent shape and you keep your foot out of it can get around 20 mpg

[@Slim_Slid]

The GM 6.2L V8's were the engines that are underpowered but so is the 6.9L & 7.3L IDI V8's from Navistar. The only easy way to upgrade that was the turbocharger kit from Gale Banks for all three engines. The GM 6.5L V8's were just bored out 6.2L V8's. The 6.5L V8's are actually good for hauling and retained the high fuel efficiency. It's debated on longevity compared to Cummins and Powerstroke. However,immense stress and different expierience will say otherwise in military service and oilfield business. These engines were good for the HMMWV's until AM General came out with the uparmored M1113-M1167 ECV's because of the extreme weight. With armor,personnel,and equipment the HMMWV's almost weigh as much as an unloaded M35A2. Despite the heavy modifications the 6500's had these engines never were reliable for the newer HMMWV's. Troops hate the Humvees and always deal with head gasket or crankshaft failures. Finally the JLTV's/LATV's since 2019 have been phasing them out of combat zones after the MRAPV's and MATV's.

[@JREACHER1954]

94 K2500 purchased new. My first diesel and not knowing any better got the ''S'' engine that was a veritable powerhouse generating about 165 hp and equipped with an egr. Still own it, but have made countless upgrades and deletions over the years. It may not be the best but it's a keeper. Treat it right and it really is a fairly dependable platform.

[@8020Media]

JR - Very true! Sounds like you've got a good one. How many miles is on it?

[@JREACHER1954]

@@8020Media Around 93k miles. Considered replacing it but with the prices now, not to mention all the emissions crap, this will suit my needs. Besides, I'm oddly attached. 😁

[@8020Media]

JR - Completely makes sense! You have many more miles to go on that one.

[@dieseltech139]

Appreciate the great content! 👍👍 I remember working for a big utility company years ago as a fleet mechanic and i was sent to GM school to learn the ins-and-outs of the 6.5 turbo diesel engine. It was new and in all our 3500 series trouble bucket trucks and at the time it was new, there was no replacable parts for injector pump so if solenoid went bad, you had to replace entire pump. Got that job down to under 4 hours R & R. I like the engine but it had some faults for sure! 🇺🇲✌️

[@8020Media]

Thanks for the feedback and taking the time to write your first hand experience with the 6.5's!

[@EMGge]

There was also different blocks that were made through out the years for the 6.5l. Some of the best thicker 6.5 blocks came out of Mexico. That's why not all 6.5s are Detriot Diesels.

[@8020Media]

E - Thanks for sharing this insight.

[@dw7094]

They are still produced in Mexico under license from GM. They are produced for several South American Armies who use GM trucks.

[@Connor4x4]

The 6.5 is actually a great engine if you want a real work truck and add a few upgrades.

[@8020Media]

Connor - This is true!

[@turnerables]

How much can it be built on a mechanical fuel pump

[@Pecas85]

I got a 98’ k2500 with the 6.5 and nv4500 transmission. I love my truck specially after I installed some upgrades from Quadstar Performance

[@8020Media]

Rigo - Sounds like you've got a beast on your hands!

[@captnhook236]

97 CCLB C3500 SRW as my daily since 2001 when i bought it, addressed the stupid design flaws, but stock heads and bottom end are at 363K 4l80 trans is bone stock as well! 27 mpg with the fuel system i have. 3 PMD and 2 injection pumps.

[@8020Media]

C - Nice! Thanks for sharing your experience.

[@robertfrey3607]

The 6.2 was a good reliable engine. Not fast, but achieved good mileage and was super easy to work on.

[@8020Media]

R - 6.2 or 6.5?

[@thathondachannel2105]

have a 93 ext cab lng bd 2500 6.5 td and 5 speed manual with that rare 93-94 only year 1st L ow gear and R of the same ratio Absolutely love it has 360k miles og engine and trans just put a new clutch and its still pulling and getting mud on the tires everyday love these engines and trucks every nay sayer wants an invincible motor or is not reliable lol they can be some of the best diesels ever on the road

[@8020Media]

That - Thanks for sharing your experience!

[@nou8257]

Got a 94 k3500 6.5 5 speed crew cab dually with that odd 1st low as well and a factory tach which i'm told is also rare.

[@thathondachannel2105]

@@nou8257 nice!!!! yeah same here got the tach too it is really rare for that style of truck ive seen only 2 others online like it any near me "250" radius dont have a tach and none manual

[@KMPandme]

Great honest documentary. I would agree haven used both the 6.2 and 6.5. GM trucks of the 90s really deserved a better diesel the trucks were very reliable add easy to work on.

[@8020Media]

K - Thanks for the feedback!

[@TheAscendedMaster]

I have daily drivien my '82 6.2 for 9 sun cycles (years) and it has been extremely fun and reliable. Once I made the necessary updates and upgrades to the old 6.2 it became a whole new machine. Over 450hp, still gets 22+ mpg and is a 4x4 3/4 ton...cant ask for more.

[@8020Media]

T - Nice! Sounds like you've got a good one. Thanks for sharing your experience!

[@v8felon]

Most modern diesels can't even make past 100k without cab removal issues

[@8020Media]

V - Not all that true, but we will say, they certainly don't make them like they used to.

[@Tht1Dude]

I've only ever heard people who DON'T own one talk garbage of it, everyone who owns one I've heard good things. Yes is has its issues, every engine does. It might be gutless but power isn't everything.

[@8020Media]

T - The sole purpose of us making this video is to inform, not scare. Also, not talking garbage, again, just sharing information.

[@Tht1Dude]

@@8020Media No I know, I was just making a general observation, not directed at you guys. Like on Reddit and TikTok and what not the only people I've heard say it's a bad engine are people who don't own one or never owned one. People who actually own one or have owned one have talked about it being pretty solid but obviously not flawless. Apologies if it came across wrong

[@8020Media]

T - No worries at all! We completely agree.

[@chooky5684]

Also the turbos gm used were far to small creating high drive/back pressure which also caused crank failure and over heating

[@8020Media]

Chooky - Very true. Thanks for sharing this insight.

[@kevinfrerichs8589]

I have personally owned several 6.2 and 6.5 well over 300,000 and never crank or major engine problems, Now! transmission problems don't even get me started.

[@8020Media]

K - Sounds like you've got good ones that you take care of! Thanks for sharing your experience.

[@stevebuttrum]

I got a 93 c2500 6.5 with 5 speed manual and 330k and it runs and drives like new

[@8020Media]

Steve - Thanks for sharing your experience!

[@jaimeramos6647]

I don't understand how the 6.5s 215HP and 440lb-ft ratings was underpowered compared to the competitors at that time? By numbers using 1996 as an example, Ford 7.3 was rated at 225 hp and 450 lb-ft. Dodge 5.9 was 215HP and 440 lb-ft. Am I missing something?

[@budwhite3570]

I have a 97 6.5l chevy cheyenne, with heavy duty tow package(manual transmission, granny gear, limited slip rear, heavier rear leaf springs, etc), I've owned for a number of years, but one thing that does anger me is I wanted to replace the lower coolant hose assembly and cannot, and like the thermostat without loads of work...looks like I have to remove all sorts of stuff, the entire front of the engine, jus to get that hose off down there,...I might as well when I do just change out a higher capacity water pump, fan clutch and higher capacity fan they talk about using. Engine has about 240,000 miles,....miles-ish,...work was supposedly done like a stud kit I cannot confirm, ,,,sure did look clean when i go it. There were so many new parts put on with just five thousand miles on it since then......, injection pump for instance, rebuilt transmission and cluth, brakes, air conditioning, new fuel tank and fuel lines, rear end limited slip rebuilt, five to seven thousand miles ago that if the engine blew I'd likely put in a new 6,5l due to cost of some other diesel engine(sure would love a cummins in there though cause the manual transmission says chrysler corp. I don't like it either, but former owner claimed to have towed huge loads, ...like 13,000 POUNDS uphill, ...I THOUGHT that all the 90's 6.5l needed a better later high flow water pump for "towing".

[@8020Media]

Bud - Sounds like you have a good one! Unfortunately, they aren't the easiest to work on. Certainly have to do a lot of things at once when you tear it down. Thanks for sharing your experience.

[@ThirteenTwentyRepair]

Former owner lied to you 😅, even after some minor upgrades my 94 Suburban struggled to pull 7,000lbs up steep grades (Tehachapi CA). I have since installed a quadstar eprom and hx35 turbo and it actually did quite well pulling 5,000 lbs up a grade at 65mph. I’m starting to gain some faith back in it as a tow rig, but 13,000? I just don’t see that.

[@budwhite3570]

@@ThirteenTwentyRepair Yeah, I've pretty much figured that was maybe bs, with my very limited to zero experience towing trailers other than military experience with large trucks years ago. Bout all I care for this unfortunate pickup I have is that I paid little for it years ago, have put little in it, and have barely used it. Now I need a new ignition switch pricing out at $178, and a few other issues. I guess right now I am lucky to own a running truck at all, errr, well, problems with the ignition switch, likely cause of moisture build up in the truck over the winter corroding connections due to it being on jack stands due to another issue,..namely I wished I owned an easier to work on truck like back in the old carburetor days, or a older good condition diesel pickup before electronics and emissions standards ruined simplicity of vehicles. Haven't put on the new lower hose of course cause I can't without removing the whole front area parts, will later with an upgraded water pump/fan clutch/fan the set known that fits being higher capacity and for the trucks several years later.

[@ThirteenTwentyRepair]

@@budwhite3570 my suburban has that later year cooling upgrade. When I was dogging hard on a 10 hour trip with a 7,000lb trailer it actually hit 210 a few times. Most of the time it lives happily at 190 all day, sitting idle at a light or 70mph.

[@JoeyDeBeck]

That's only when you over work the motor. They were not meant to work all day and all night. There's a rating on diesels for a reason. 12v is just as bad in stock form if you over work it. I had one in my boat had it professionally rebuilt. 1750 hrs later the cookies came out the exhaust pipe. 6068 deere for the win. I'm planning to put one in my 97 k2500.

[@8020Media]

J - And how they are maintained. Thanks for sharing your experience and feedback.

[@Slim_Slid]

I agree with this. Many 6.2L/6.5L V8's became heavily disdained in the oilfield business because these engines weren't really meant for extreme usage. It got to the point where some companies just didn't want to deal with any GM trucks unless it was a large rig with a Detroit Diesel or both a smaller and bigger truck that had a big block instead. For awhile many of them preferred both Ford and Dodge. The 6.2L/6.5L V8's were great in the military for the CUCV's,HMMWV's,and CUCV ll's until AM General messed alot of things up starting with the ECV's. Even though the 6500's were the upmost modified variables of the 6.5L V8's it was a fatal mistake on all accounts using them in uparmored M1113-M1167 HMMWV's. There was countless incidents of head gasket and crankshaft failures,even in combat zones. Finally Oshkosh Defense came out with the JLTV's/LATV's back in 2019 and solved the issues. There was the MRAPV's and MATV's before that but those trucks are too heavy and at a disadvantage in certain situations even though much better in reliability and torque.

[@8020Media]

S - Thanks for taking the time to share this insight!

[@brycepoetker7080]

Crank failures were also largely contributed too by the fact that gm cheeped out in material and went with cast iron instead of forged steel like in the p400 military engines, of wich was the called or material my the designers of the 6.5 but gm has to be gm and they have to make money some how right. From research I have done it also matters which company made the particular engine on a case by case basis. Because as far as I know and others feel free to call me out and hold me too it respectfully of course that GM(detroit diesel)themselves, international and optimizer. And by my knowledge they international and optimizer were the better motors. But the optimizer (p400) being the best. Again feel free to correct if I am wrong but but whatever you do plz don't be mean about it.

[@8020Media]

Bryce - Thanks for taking the time to add this insight.

[@normblais7527]

Hi, I seen your old post and thought I would ask your advice. I have a 6500 pound camper trailer do you think a 6.5 would do the job without constantly downshifting went in cruise control or should I move up to a D max. your thoughts would be appreciated. Thanks.

[@8020Media]

N - Personally we like the Duramax's more. That's not to say the 6.5 isn't capable enough though.

[@josephheasley615]

I owned an 82 6.2 j code in a one ton truck I had the factory book and mine did exactly what it said it should do I had 175k miles on it when I sold it never had the heads off and still ran like a champ

[@8020Media]

Joseph - Sounds like you took great care of it! Thanks for sharing your experience.

[@jeffdelorey1981]

I watched a video, guy said he got his up to 500 hp seems excessive, but nothing is impossible

[@8020Media]

J - Seems aggressive, what'd they have?

[@jesses.7107]

I love my Detroit idi best truck ive ever owned

[@8020Media]

J - They can be workhorses if taken care of properly!

[@brayanamador14]

Is it possible to engine swap a 6.5 from a LML?

[@8020Media]

Talking swap an LML into a C/K? Can't say I've seen it done or can provide much guidance on how to do it but most things are possible with enough $ - I doubt it would be cheap tho so depends if you're doing it for practicality or just for fun because you can.

[@jeffdelorey1981]

A mechanic that worked on my 6.5 said a 5.9 Cummings will slip right in there🤷‍♂️

[@8020Media]

J - I'm sure it wouldn't be cheap, but thanks for sharing the insight.

[@pinchnloaf]

The 6.5 NA in a 1/2 ton was ok. But as they turbo’d them, worked the engine harder and caused more heat and didn’t manage that all correctly that’s when they got worse and worse. I remember one of the big upgrades back in the day was getting a hummer military 6.5 block that was supposed to be significantly better than the cheap one GM used in consumer model vehicles

[@8020Media]

Yepp definitely a lot of problems with cooling on these engines! Curious about the military block, that's interesting but makes sense those would be manufactured a bit stronger.

[@Slim_Slid]

The 6500's/P400's are actually much better than basic 6.5L V8's,espiecally because of the forged crankshafts,but GM should've entirely only used those engines for civilian usage which they did eventually later on. It was a massive mistake intialising those engines for the HMMWV's/ECV's. AM General only held onto the 6.5L V8's under contract from GM because of how cheap and distributed they were. They didn't want to figure out what more capable transmission and engine that possibly could've been used as replacements. The 6500's had numerous head gasket and crankshaft failures in the uparmored M1113-M1167 ECV's despite all the glorious modifications. Troops heavily disdain the Humvees because of that. That's why Oshkosh Defense as of five years ago finally debut the JLTV's/LATV's which are blends of HMMWV's and MRAPV's as one truck. The actual MRAPV's and MATV's were still better choices but flawed in some aspects for combat.

[@wadofbat]

Lookin at getting my first diesel, I’ve heard 6.5s have their issues but are cheaper to maintain compared to a 7.3 as good as it is but it’s a bit more expensive to maintain. If anyone has thoughts on this I would love some feedback/support!

[@8020Media]

Wad - We have a 7.3 and love it. However, both are great engines.

[@ericpratt-d4b]

7.3 regardless of their unearned reputation .... are very expensive to keep running .... like failed turbos / injector cups / glow plug failures / and glow plug controller failure / high pressure oil pump to fire the injectors failures/ and lots more / But owners love the ability to "rolling coals !/ something that will destroy the 6.5L. If one is honest and compares the total costs of each engine .... the 6.5L wins hands down. also it only needs 6 quarts to change the oil. Unfortunately it is difficult to find a well maintained 6.5L used since if the owner kept it up..... they do not want to part with them... Next time someone brings up the comment that they are POS.... ask him when did he owned one. Like earlier comments 99.995% of loud mouths ... never owned a diesel. Sorry I am keeping mine until the body disappears. Wish I kept my none turbo 6.2L but the body was beyond saving.

[@jakestuve9585]

Well actually gm worst engine was the 5.7 olds diesel

[@8020Media]

Jake - Thanks for sharing this insight.

[@ericarntson2035]

Anyone remember the Oldsmobile 350 diesel? Those were far worse than the 6.2/6.5.

[@8020Media]

Eric - Very true!

[@daniandreotti3892]

Would mechanical injection, NO PMD, be better?

[@8020Media]

Absolutely, the DS2 mechanical pumps they used before switching to the DS4's were a lot more reliable.

[@Alberta_MTN_Bear]

I’m not entirely sure that the engineers did a terrible job, it’s the morons who thought slapping a massive turbo on it was a good idea.

[@8020Media]

A - lol good point!

[@gregday9943]

7.3 at its best only made 275 hp and 550 pound feet and 12v only made 215 and 440

[@8020Media]

G - Thanks for the insight.

[@gregday9943]

But the 6.5 while decent was not as heavy duty as the 12v or the 7.3 tho tge 7.3 is overated imo. Am general still makes the 6.5 optimizer which is better then the orginal but not as good as the other two

[@8020Media]

Thanks for sharing!

[@kriegsy69]

​@gregday9943 overrated? See lots of 7.3's over a million miles. Never heard of a 6.5 ever getting close to that

[@angrybobking5083]

move the PCM away from the heat and they are bulletproof

[@8020Media]

A - Well said.

[@hovincustoms]

BS. Get rid of egr and make sure you follow MAINTENANCE on a utility vehicle 😂👍🏻 And many forget to maintain the crankcase depression system

[@8020Media]

H - What's BS?

[@markst.germain9286]

I had a 97 one ton . Four injection pumps later I bought a ford.

[@8020Media]

Dang, that's a lot of failed injection pumps...but yeah, not the greatest engine from GM especially compared to what Ford and Dodge were putting out at the time.

[@1028entllc]

I need one rebuilt

[@8020Media]

1 - Sorry to hear.

[@jeffdelorey1981]

I'll say it again, bigger injectors

[@8020Media]

J - Very true.

[@tomaszkrolak9958]

Witam.Chcę kupić chevrolet express 6,5 TD L65 z przebiegiem 403000 mil,auto jest z 2003 r,proszę o opinie,co jest wart ten silnik,dziękuję i pozdrawiam.

[@8020Media]

T - Osobiście byśmy tego nie zrobili. 403 000 mil to mnóstwo mil i myślę, że możesz kupić coś lepszego. Mamy nadzieję, że to dobrze zostało przetłumaczone.

[@StevenGibson-d1b]

Just buy a new downpipe ill fix it for you for free!!! We need more videos of the truck please!!

[@8020Media]

S - Thanks for the insight.

[@StevenGibson-d1b]

​@@8020MediaNot a problem:)

[@michaelatkin9649]

This sounds like all GM fuck ups except the harmonic balancer

[@8020Media]

M - Thanks for the insight.

[@taylorh3930]

The 6.2 and 6.5 ARE NOT A DETROIT!!!!!!!!!!!!!!!!!!!! The 6.2 and 6.5 were produced by General motors NOT by Detroit!!!!!!!!!!!!!!!!!!!!!

[@8020Media]

Taylor - These engines were made by GM under the Detroit Diesel subsidiary. So, we are both correct.