6.2 questions from a new-guy

[saxart]

Hi-
New guy here...

I'm looking for information regarding the 6.2L Diesel engine used in the GM pick-ups from the Mid-1980's.

I have a good friend, who is a gear-head and a FORD fan that keeps saying, "The GM 6.2's are not a good engine, stay away from those trucks."

So, I'm looking for comments about his thoughts. Were there "bad" 6.2s and "good" 6.2s? (Are the military issue 6.2's different from a civilian engine of the same era?) I don't seem to see anyone on this forum complaining about these engines, so I'm not sure where he gets this info from.

Also, since we're on the subject, what are the weak areas of these engines? What should a new-guy (who knows his way around under the hood of a truck, but is generally unfamailar with diesel engines) look for?

Thanks for the thoughts!

 

[MT4222]

The 6.2 detroit diesel is not a bad engine. The military version is a j code so it is slightly different. The only real problem with these motors is their lack of power. With these 6.2s majority of the issues we have are with the glow plugs and the injection pump. As long as your not looking to go anywhere to fast they are a pretty good motor.

 

[Chief_919]

Nothing wrong with the 6.2 as long as you don;t run it up on the governor all the time and keep up on maintenance.

Ask him for details on why they are bad- if he says anything like "It is just a gas engine converted to diesel", just walk away knowing he is an idiot without a clue just repeating bad info somebody else gave him.

 

[DriverSideImpact1008]

The old Ford non-turbo 6.9L and 7.3L diesels are better as far as speed and power (even over the 6.5 turbo), but 6.2's have better fuel economy.
They both use very similar fuel injection components (some parts are even the same) and a similar glow plug system.

The 6.9/7.3 might be a little more durable (they were designed for medium duty applications), but it mainly comes down to the maintenace over the years regardless of the truck/engine. Most problems on old trucks happen from years of poor maintenace.

I've seen a very early (like 1982) 6.2L diesel with tons of miles on it run great, and I've seen a 7.3 IDI in a 1989 F250 with 140k run like crap and need an engine rebuild.

Heck, even the 5.7L diesels can be reliable if they're properly maintained and treated well.

 

[BIG_RED]

If someone is used to a gas engine and doesn't treat a 6.2 like a diesel, it won't last very long. This doesn't make the 6.2 a bad engine, it makes whoever abused one a bad operator. They need more time to warm up before you drive them (if you want them to last) and they do not like high RPM's. They need clean fuel and good/clean fuel filters. If you're looking to buy a 6.2 equipped truck, mind the RPM thing.. The M1008 series are great 5/4 ton trucks, but IMHO they have a top speed of about 55 MPH if you want them to last a long time (this is frequently debated). They're AWESOME farm/around-town trucks. Not ideal for the interstate.

Also I would suggest you do a search for "reliability 6.2" or something along those lines, as this topic has been discussed many times before. I love my M1009. She's my DD. 40 Miles a day for the last 3 years. She's a little loud, but always gets me there. Cheap on fuel too (for a fullsize truck).

 

[emr]

The Military even has it in print they did not live up to expectations, they are a low mile motor, GM tried to go the cheap route into the diesel market, it did not work, many have them on this site, And some will say they are awesome and a high miler, That may be true for a select few, but the facts are they did not last on the street, and in service they are only still around because the ones being auctioned off are extremely low milers, the only reason they are still around, The block is a 454 sent down another assembly line and turned into a diesel on the cheap, These are the basics, like anything U will find those who have an exception , The trucks that served have a cool factor that makes em worth putting up with, But there are allot of better motors out there.
With that said I agree with driversideimpact1008, That is the basic truth, its not so bad it wont work for you, but the masses ( general public) never had a chance with them, low mile motor for most for sure...As for being an idiot on the 454 block, it is , sad but true. one should be careful who is called names .

 

[Chief_919]

The Military even has it in print they did not live up to expectations, they are a low mile motor, GM tried to go the cheap route into the diesel market, it did not work, many have them on this site, And some will say they are awesome and a high miler, That may be true for a select few, but the facts are they did not last on the street, and in service they are only still around because the ones being auctioned off are extremely low milers, the only reason they are still around, The block is a 454 sent down another assembly line and turned into a diesel on the cheap, These are the basics, like anything U will find those who have an exception , The trucks that served have a cool factor that makes em worth putting up with, But there are allot of better motors out there.
With that said I agree with driversideimpact1008, That is the basic truth, its not so bad it wont work for you, but the masses ( general public) never had a chance with them, low mile motor for most for sure...As for being an idiot on the 454 block, it is , sad but true. one should be careful who is called names .

It is not a 454 block, it is not a gas block, it was designed from the ground up as a diesel engine.

Please quit repeating that lie.

 

[combatmech]

I have been using my M1009 as a daily driver for almost three years now. Plus, just drove it 1300 miles ( Va Beach to Dallas ). It was the slow boat to Texas,( so my wife says ) but it's amazing the things you see at 60-65 mph. I added half a quart of oil at the halfway point during the trip. Average MPG for the trip was about 19......
Although I am still new to diesels, I would take an older GM diesel any day.
Your friend needs to do his homework......

 

[Keith_J]

One obvious clue this is NOT a small OR big block diesel is the CLOSED VALLEY. On any Chevy V8, cam tappets can be removed and replaced by removing the intake manifold and using an extractor through the cylinder head.

Not so on the Detroit Diesel V8. The cylinder heads must be removed.

The weak point of this engine is harmonics on the crank damper. IMHO, the harmonic damper is weak as it uses rubber as the spring-damper element. They work fine when new, rubber ages and when it gets hard, it no longer damps the lower frequencies, leading to fatigue of the crank and block.

The ONLY common feature of this block with Chevy V8s is the bolt pattern to the transmission/bell housing.

 

[Recovry4x4]

The Military even has it in print they did not live up to expectations, they are a low mile motor, GM tried to go the cheap route into the diesel market, it did not work, many have them on this site, And some will say they are awesome and a high miler, That may be true for a select few, but the facts are they did not last on the street, and in service they are only still around because the ones being auctioned off are extremely low milers, the only reason they are still around, The block is a 454 sent down another assembly line and turned into a diesel on the cheap, These are the basics, like anything U will find those who have an exception , The trucks that served have a cool factor that makes em worth putting up with, But there are allot of better motors out there.
With that said I agree with driversideimpact1008, That is the basic truth, its not so bad it wont work for you, but the masses ( general public) never had a chance with them, low mile motor for most for sure...As for being an idiot on the 454 block, it is , sad but true. one should be careful who is called names .

I thought it was a converted flathead straight 8 block.

 

[BIG_RED]

I can confirm, the 6.2 Diesel IS NOT a 454 block. It's block was purpose built as a diesel. It wasn't the best design, as the main bearing webs have a tendency to crack off the block. The reason seems to be that there just isn't enough metal right where the webs meet the rest of the block (if you take one apart and look, and have seem other diesel engine blocks, the 6.2's casting looks very thin there). They couldn't fix this on the casting without making the whole engine block longer (increasing the bore spacing), which they wanted to avoid, because this engine was to be a "drop in" replacement for Chevy small blocks (which wouldn't work if they had to move the rad's and engine mounts forward on every vehicle fitted with this diesel to accommodate a longer engine block). Yes, gm was being cheap (Don't get me wrong, I love gm). No this is not a gas engine converted to a diesel. The only engine GM ever produced that used a modified gasser block was the Oldsmobile 350 diesel. The main bearing web failure problem on 6.2's is reportedly "fixed" on the new 6500 Military engines (not all 6.5 military blocks, only the latest generation) by using a stronger alloy to make the block out of. Also, it is a common thought that by tying the main bearing webs together with a "stud girdle", one can prevent the webs from moving around, thereby preventing the metal fatigue that causes the cracks. This claim is not yet proven as far as I know.

 

[trukhead]

I have a low milage M1008 and use it around the farm and it is just fantastic at low speed. I have taken it on the road and I don't like operating it faster than 45 MPH. One could change the gears but then you would sacrifice power. The 4.56 gears in this truck are too slow to make this a commuter vehicle. I think the engine is weaker in design and I don't want to stress it by over revving it.

I think the M1009 is ok for highway speeds with its 3.08 gears though I wouldn't go over 65MPH.

I like the way the 6.2 runs, starts and in general operates.
It however is a low power engine that was an attempt at creating a diesel vehicle on a budget.

I never cared for chevies until I got the CUCV and I think it is a good truck within its limitations.

 

[chevyCUCV]

Ya the 6.2 is a garbage motor
Everyone here who owns them thinks that too

What do you think the answer will be on a chevy based sub section?

Quit trolling and try the search feature

 

[PAm1009]

I love my DD 6.2 and will take one all day everyday. Its reliable great on fuel and pretty basic for a diesel being my first. If you dont like a 6.2 dont buy one

 

[Warthog]

This discussion is better suited for a true diiesel forum where they live and breath the 6.2L 6.5L

A couple of them are

www.thedieselpage.com
www.dieselplace.com

The 6.2L was designed in the late '70s/early '80s to be a fuel sipper. It lives up to that task.

It was never designed to be a powerhouse 6gazzion hp enginne.

Sure it has its issues. What engine doesn't

 

[saxart]

Wow, thanks for all of the thoughts so far. I get a great sense of what these trucks (and these 6.2 engines) are all about by some of the comments you've posted today.

ChevyCUCV-
Um... Wow! Not sure what the problem is. I'm certainly not new to the world of forums, and I did the requsite searching BEFORE posting this question, but I just couldn't find the info I was looking for. I'll admit my search skills must not be up to par, but that's certainly no reason to smoke-out the new guy. Perhaps you should just ignore any future posts I make from this point on, and then we should be just fine.

Anyway, thanks to all the rest of the members for your descriptive posts! I'll probably have more questions as time goes on. I really apprecaite your HONEST thoughts today.