hi guys. i am confused. on forums like this, people seem to bag the shit out of the V8 chev diesel. the most charitable people say they are gutless, but with reasonable fuel economy. where in australia, there is a mob who puts them into landcruisers, patrols and light trucks all the time. people rave on about low end torque and fuel economy. is it just that the jap diesels are pos ? all the engines get a full rebuild, and have mechanical pumps. some are sold turbocharged.
"Low end torque and fuel economy" when compared to what? I've got over 40 6.2 diesel rigs - Suburbans, Blazers, trucks, etc. Mostly future projects and parts vehicles - but I have six that are road-worthy and I swap back and forth by seasons. In the winter, all my snow-plow rigs are 6.2 diesel Blazers. I also have two small 4WD motorhomes with 6.2 diesels.
I was a John Deere diesel mechanic when the 6.2s came out new. I drove many, and fixed many at that time - and ever since. My opinion is - the best thing about them is they are cheap to buy, and cheap to fix. I still find complete engines, or trucks with running engines for $150 or less. I wish I could find some Cummins in that price-range.
In regard to low-end torque - it's about the same as 305 gasser - not very much. 6.2 was originally designed to be a power-equivalent to the 305 and that's about what it is. I've seen many blow to pieces with 60K miles on them, and I had one - in my 87 Suburban, make it to 520,000 mile before the crank and block blew to pieces.
My biggest complaint is - they can be running fine - and all of a sudden - blow to pieces with no advance warning. I assume it's a quality control issue with cast-iron crankshafts and cylinder-blocks. 6.2s are prone to developing cracks by the main-bearing webs. That gets worse over time - and at some point - finally let go. When my 87 Burb blew-up - it was still starting and running like the day it was new. Eating oil, yes. But otherwise - it got 13-19 MPG, had high oil-pressure, and sounded perfect. Cruising down the highway at 70 MPH - it just all of sudden, blew-up.
It is my opinion, that any properly designed engine should die slowly and give warning - not run great up to the moment it blows.
The newest 6.5s being made now (6500 Optimizers) have much heavier heads and blocks - but the cranks are still cast-iron. Hopefully, quality control has improved.
The reality is - if you buy an engine for $150, then pull the oil-pan and check for web-cracks (and find none), you can probably get a lot of use out of it. Injection pumps are fine after 1985 and older pumps should pretty much all be updated by now. But, a 6.2 has a lot of cubic inches and will never be real good on fuel mileage. A Cummins 3.9 can make the same power - if not more - since it can handle high turbo boost and act "bigger" when needed, and "smaller" when needed.
Don't pay attention to the high failure rate in military engines - since they are abused something awful overseas. Thin fuel, high heat, and vehicles overloaded with armour. US Army says most 6.2s/6.5s last 1000 miles at best in hard use.
My best fuel-mileage 6.2 is in a 1982 K10 4WD truck withi 3.08 axles, and a four-speed manual overdrive trans. It gets a high of 24 MPG on a flat highway and 16 MPG local driving. My Blazers all get around 20 MPG, my 3/4 Burbs around 18-19 MPG best, and 1/2 ton Burbs with OD around 20 MPG.
I've also pulled a 21 foot camper thousands of miles with a 6.2 diesel Blazer and averaged 13.2 MPG for the trips.