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Discussion Starter #1
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.
 

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Hello,
I work at a shop where we have 4 service trucks with 6.5's in them. Only 1 of these has pretty good power and the other 3 run about like a 305v-8 smog motor. They are reliable and get around 15mpg in a 7200lb service truck, but if left stock are no speed demon.
Ed
 

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The engines are just not a good engine. They are a light built diesel....which does not work well for the longevity batting average. The will break cranks and blocks with no warning and grenade....that is a small issue. They are also prone to crack heads. Of coures, my 12V cracked a head as well after replacing a 6.5 with it..... so I dont know if that arguement works. All jokes aside, they are prone to crack heads and to run hot. Cold starts are a bear if everything is not just so-so. And, they are also gutless. As for fuel economy, mine got 12MPG in my V3500 4x4.

I replaced my 6.5 T with a 12V cummins when it broke a PS pump pulley and over heated. I just was not going to spend a bunch of money on a chevy diesel when I could do a cummins swap for about the same money.
 

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The 6.2 NA diesels I've driven are gutless, are not "diesel" reliable, and get horrible gas mileage. They offer no benefit, over say a gas 350, what so ever, in my opinion. They are also NA so they are severly affected by altitude and all the other issues that affect NA motors. I think they can be tuned well and are not that bad a base with a turbo potentially. but there are much better engines to start with. But as a result, they are "appropriately" priced in my opinon. The big issue I have heard from them is injection pump issues. If that can be resolved, then with a light turbo is could be a decent engine. But again I wouldn't look at one personally...
 

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Discussion Starter #6
these are all things i've heard before about them. i guess if most of the cars they get fitted to are 4400-odd lbs. and manual, they might be ok ? the people who fit all of these engines imported my 4BT, so they're not all bad. the 1HZ ( toyota ) and TD42 ( nissan ) engines we get here wouldn't pull a sailor off your sister.
 

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My Chevy had two 6.2's that broke cranks before swaping the cummins in 10 years ago. My Dad drove one 340,000 before he died. I still have the Jimmy and drive it hunting,......Hummmm come to think of it,...You can hear it a mile away, maybe that's why I never have to clean anythang LOL

Here's a bolt on power upgrade that will give you 2/3rd's more power LOL

Just messin with ya!
 

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if it is going to be a driver i wouldn't hesitate owning a 6.2 or the mech version of the 6.5 . that being said it won't last as long as most cummins and the mileage is not as good . we have two 6.2s and two 6.5s on the farm with anywhere from 200k on them down to 10k. i have replace one that broke the crank after pulling stock trailer at least half its life 225k on that one. never pulled the pan or heads on any of them . pumps are cheaper and last less time. if i was going to buy a rig with something in it a gm mech inj rig is fine if i was going to take the time to put a motor in something go with cummins. i have a 93 ctd and a 91 ctd my brother uses the heck out of his 97 ctd. dad now has a dmax with a stick and i hate sensors. only problem with his dmax is that it is a stick. and the clutch is bad stuff.
 

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Ended my time (91-98) in Uncle Sam's Motorcycle Club (E-5, 3521) running a shop for a 155mm gun battery. Had 12-13 "hummers" all with the 6.2NA, they were run hard (lots of cold starts with ether, off road, bad drivers:rasta:) all had glow plug issues, were truly gutless - even with the insane hub gear reduction, they got the job done I guess. Only saw one with a bad IP in all that time, did see a few cracked cranks.

Military app. for this engine in a 8000lb platform was marginal in my opinion - never saw a 6.5.

Don't know if this info helps......
 

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....Military app. for this engine in a 8000lb platform was marginal in my opinion - never saw a 6.5......
they are all 6.5 motors in the HMMWVs now. i hate those motors. i ran the largest maintenance company on Ft. Stewart for a few years. in my time, i think we changed almost 300 engines (over a fleet of 2500 for the division), just as many heads, and at least a thousand IPs. i've seen those motors do it all: con rods, broke pistons, broke cranks, cracked blocks, you name it. and that's all after the unit has done all their maintenance (injectors, plugs, manifolds, radiators, etc). oh, and all this on what we'd consider "low mileage" - if HMMWVs made it over 20k miles on a motor it would be considered "abnormal."

i'm not exactly a big proponent of those motors.
 
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Happy with a 6.5

I was elated when I spoke to my wife from Iraq. My 6.5 died. The 6.5 in my pickup locked up and my wife and the truck were towed home...she felt guilty for driving it when it broke.
"You're not upset?" No, I'm pulling it and putting a Cummins in it!
And now, over a 100,000 later, no regrets.

I bought my first 6.2L in 1982, and a GM diesel till 2001. I turbo the 6.2, I put low compression piston in the 6.5 and you cannot drag race volkswagons.
Well, you can, you may not win.
Wayne
 

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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.
 

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Military 6.2 & 6.5

Been working on them for over 25 years. Army does not get many miles from them, they suffer from typical V-8 diesel heat woes. Rear cylinders wear too quickly, head gaskets fail, and usually on rear. Culprit is usually fan clutch, time delay module, and good gracious, glow plugs, glow plugs, fail, fail. In desert heat, the engines we tore down suffered top end oiling issues, even rear cam bearings were blueing. It just don't cool well enugh.
In 96, GM up'd the water pump from 80 GPM to 130 GPM, installed dual thermostat, all attempts to fix heat woes.
Standadyne was supposed to fix pumps to allow them to function on JP-8 fuel, but still same parts, and the pumps fail to pump when hot, soldiers pour water over rear of pump, and low pressure pump tolorance returns to start hot, otherwise once running in desert, must stay running. Not uniquely a 6.2-6.5 problem, a problem for all rotary style pumps.
Since the military uses de-tuned engines, cracked blocks are not the problem of civilian more powerful engines. When I put low compression pistons in a 98 oil cooled block, it promptly cracked, the 93 non-oil block was fine, however it gave up at 44K with a broken rod brg stud. (POS)
Granted my 6.5 gave me equal fuel economy at 55-65, the 6.5 bests the Cummins at 70-80 (economy only), the Cummins replacement outpulls, outlast, and definetly out-grunts the GM V8 diesel, and well, its just better.
I not running another GM 6.2-6.5. Finished.
Wayne
 

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Gm want to sell replacement motors and vehicles. They are built to have a short life.
Then add a lot of GM quality control, and you have a chevy v8 diesel!!!
Any correctly designed diesel should go at least 500,000 miles.
Gm has done a lot to destroy the us diesel market.
The old 5.7 was a short stroke diesel.
Who would of thought up that idea???
 

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Gm want to sell replacement motors and vehicles. They are built to have a short life.
Then add a lot of GM quality control, and you have a chevy v8 diesel!!!
Any correctly designed diesel should go at least 500,000 miles.
Gm has done a lot to destroy the us diesel market.
The old 5.7 was a short stroke diesel.
Who would of thought up that idea???
No, not any diesel is built to last 500,000 miles. Heavy duty diesels yes to a certain degree - but the GM 6.2 was never intended to be, nor was it marketed as a HD diesel.

Medim and Heavy duty diesels are sold with projected life-spans called "B" ratings. For example, a 5.9 Cummings diesel has a B10 rating of 210-250,000 miles and a B50 of 350,000 miles. A "B10" means only 10 do NOT make it during the miles stated without a teardown. So, even with the 5.9 Cummins, 50% do NOT make it to 350,000 miles when used hard.

6.2 and 6.5 was never B tested or rated, the Duramax has been.

GM certainly made some bad engines - but it's not them that screwed up the diesel market at the consumer level. It's mostly due to owner and repair shop ignorance. I worked on the first Oldsmobile diesels when they first came out late 70s - much being warranty work. Yes, they had some pretty bad problems - but even more so with owners who were clueless and repair shops with mechanics who were also clueless with diesels. Many still are. In fact, that time, many Chevy dealers did not know how to work on them. Thusly, many perfectly engines got pulled and swapped over to gas, or Mr.Goodwrench replacement engines.

As far a the Olds engines being short-stroked? Well, they were built to offer fuel economy duing a fuel crunch - not power. They were built over the exisiting gas-engine Oldsmobile platform - just as many - many other diesels were - including several International Harvester diesels, Hercules, Continental, Isuzu, Nissan, etc. Short-stroke can result in a wider RPM range than a HD long-stroke diesel and it's not always bad in light use. GM did not offer the 350 with a standard trans., or 4WD, or any towing - it was light-duty only.

5.7 liter 350 Olds diesel, 4.05” X 3.38”, 125 horse at 3600 RPM, 225 TQ at
1600 RPM
6.2 GM bore 3.98” and stroke 3.8” highest torque rating 248 lb. ft.
6.5 GM bore 4.06” and stroke 3.8” VIN-F 240 lb. ft. at 2000 RPM
6.9 Ford IH bore 4” and stroke 4.18” (more tractor-like than a 6.2) 315 lb. ft. at 1400 RPM
7.3 Ford IH bore 4.1” and stroke 4.18” 345 lb. ft. at 1400 RPM
7.3 Ford IH IDI Turbo - 4.1” bore and stroke 4.18” 395 lb. ft. at 1400 RPM
5.9 Dodge Cummins Turbo 4” bore and 4.7” stroke. 400 lb. ft. at 1700 RPM
 

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In my experience, Aussies seem to be far more tolerant of fuel thirsty engines than others.
It's probably a result of the Aussie car industry which pumps out mainly fullsize sedans and wagons with big 6's or V8's.

The fuel figures of the chev V8 diesels don't seem impressive. 13.5l/100km is mentioned in a brunswick testimonial where a stock diesel landcruiser of similar size (maybe bigger) will use 12l/100km or less.
Personally indirect injection is enough to turn me cold (without the rest). Harder starting, weaker heads and the associated fuel economy penalty.

The Aussie military fitted Isuzu 4BD1's and 4BD1T's to their landrovers in the 80's. I doubt they treat their vehicles any better than the US military does and they have a great reputation.
 

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The fuel figures of the chev V8 diesels don't seem impressive. 13.5l/100km is mentioned in a brunswick testimonial where a stock diesel landcruiser of similar size (maybe bigger) will use 12l/100km or less.
Personally indirect injection is enough to turn me cold (without the rest). Harder starting, weaker heads and the associated fuel economy penalty.

The Aussie military fitted Isuzu 4BD1's and 4BD1T's to their landrovers in the 80's. I doubt they treat their vehicles any better than the US military does and they have a great reputation.
Those fuel mileage figures you posted are about what a diesel Chevy Blazer here in the US gets with a 6.2 - depending on gearing, 18 MPG is about right for highway cruising (13.5l/100km). Some do a little better when geared with 3.08 axles. I know of a few Blazers with Cummins 3.9s and they do better yet - up around 25 MPG (9.25L/100Km).

In regard to how our military uses or abuse rigs as compared to Australia, I don't have a clue. But - most of the US military issues of high-failure rates are due to:
1. high heat and using JP8 fuel with rotary Stanadyne pumps.
2. retrofitted armour plates that overload many 6.2 vehicles

I assume the Australian rigs you mention probably have in-line injection pumps and also not the same overloading issues. But - I'm only guessing since I know zero about the Australian military.
 

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GM 5.7L diesel

Ironically, being cheap (built) is what doom the 5.7L Oldsmobile engine. It came with an inadequate water separator that square box filter, and the standadyne fuel injector pump did not have the water bleed off inside the pump which is now standard in the 6.2 / 6.5 MFI pumps, as well most rotary style pumps. Inside now, is a screw insert with a wire thru it, that bleeds water return back to the tank. Most of the 5.7s broke the crank. In those standadyne pumps the govenor race ring was plastic, and water and hot plastic disentigrate and when that happened the crank often broke. New engines fixed the problem in warrenty, and GM gave diesels a bad rep. All because of being made cheap.

I bought a 1979 Olds and got 420,000 on it and sold it to a fella in CA (a friend - who called me a couple years later cussing (joking) about that POS I sold him, blew the engine and stranded him in Palo Alto. How many miles are on it now, 20,000. I said do you realize that is 520,000? Yeah, he joke, now where can I get another engine. I directed him to a fella in Monterey, and last I heard he had another 200K on that engine. That car had a Racor water separator. Average fuel economy 32MPG, worst 26, best 36. Great economy, but gutless.

Most of them never made it over 100K.

Wayne
 

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A stainless steel replacement ring was available for a while. The head bolts needed to be retorqued periodically and most people didn't do that. The factory usually put too much injection timing for the amount of compression too. A guy brought his Chevy pickup to my college teacher, because he didn't like the way his 5.7L Olds was running. My teacher adjusted the timing with a timing light, instead of using the lineup marks on the injection pump. It was way off! That 5.7L was one of the quietest indirect-injected diesels I have ever heard, had more power, and got 1.5 mpg better fuel economy. Another guy I knew freed up the exhaust on his 5.7L C10 and had a tremendous torque increase. He did amazing burnouts with that truck. I believe that leaving them stock and not maintaining them properly led to their problems. 30 mpg was popular! And the ones that didn’t rattle like crazy from the factory were the ones that lasted!
 
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