OOOOOOOOOOO, another old thread. Anywho on the 5.7 gm diesels, the head bolts werent nesesarilly small, they are 1/2"IIRC. BUT they didnt use enough of them. I heard it was because they wanted to share the tooling with the gas motors. Our IDIs have 34 head bolts and the 5.7's have 20. They also have a timing chain set. Which works great but isn't as reliable as gears. The 6.2's and 6.5's were better with the same 34 head bolts the IH's have.

They weren't built to be pulling motors gm built them more for milage. My old 90 F-150 300-6 RIP would out pull my dads 88 2500 with the 6.2 and not even complain. same 20ft car hauler same 120 72lb bales The ol 300 would slow on the hills but not as much as the 6.2 and also wouldn't be running 240*coolant temp at the top.
When i had my idi apart for rear brakes i drove the 6.2 for a few days til my drums came in, and it was SLOW i felt like is was in everyones way, but i did get 23mpg!

 

i have to agree with 84, the 6.2 is actually a pretty good little engine, you just have to be patient with it. it'll get ya there...with awsome fuel econemy...it just takes longer. driving the old 6.2 we had was like driving miss daisy.

 

Good god I hate that engine with a burning passion, anyone who thinks it has any good parts about it shoudl drive a HMMMV. It is pathetic even the soft top light version that looks semi-looks like a pickup is gutless. the 6.5....still gutless even with a turbocharger on it. The Canvas topped ones....0-60....roughly 45 seconds...you have to stomp on it to get it to even move the HMMMV. The military also put these in blazers...still gutless with less vehicle to pull around. It gets crappy mileage too...MAYBE 15 on a day you baby it on the highway @ 55 mph with a tailwind.

 

Just had to replace the injector pump on my dad's 93 6.5 TD. Took over 2 hours just to get the old one out. I can R&R the pump, lines and injectors on a ford IDI in that time!

Finally got it all back in and too FOREVER to prime. GM put the injectors under the valve covers which not only makes it harder to reach but also increases the injector line length, so air takes that much longer to purge.

Having said all that, the truck pulls great now, and its smooth and quiet, so he's happy. We'll see if it can ever get the sky high MPGs I hear they should be capable of now that it has recent nozzles, timing chain, and a new injector pump. Best we ever saw with the truck was 18~19 MPG with a bed cover and speeds below 70 MPH (on high sulfur diesel!).

I'd consider using a 6.2 in a half ton truck with overdrive transmission, however after seeing what the heavier 6.9 can do in a half ton, I'd just as soon go that route.

Sorry for the rant, I'm still sore in places I didn't know I had after squatting under the hood of that engine for hours on end. LOL good times....

 

Reminds me of putting my turbo kit on!

 

The military equipped the HMMWV and CUCV with the 6.2L for a reason and they get poor fuel economy because of their gearing, tires, the environmentally friendly fuel they run and the overall shape of the vehicle. The 6.2L is a good motor when you actually go through it and fix the known issues with the motor... just like every other older mechanical diesel motor. I read a nice write-up on a 6.2L build. When it was finished and dyno'd it had more HP & torque than a brand new Duramax.

 

450,000 miles still pull anything you can hook to it. still all original engine