Info on a Diesel - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1984Silverado4x4 · 07-06-2007, 06:23 PM

my brothers looking at a 1986 GMC with the 6.2 diesel and a 4spd in it. How reliable are these diesels.

The guy wants $750 for it and says it runs great. from the outside it looks alright we havent looked close at it yet.

Do you think it would be worth buying?

Russell · 07-06-2007, 10:03 PM

If you don't except it to pull like a Cummins, or accelerate like a modern Powerstroke / Duramax, those 6.2L diesels are pretty reliable little engines. They are classified as light duty diesels, and are not designed with towing in mind, just getting great gas mileage in a daily driver.

I'd put one at similar acceleration to a 4.3L V6, but with tons more torque. My 4.3L truck is bogged right down and looses the gas mileage it normally gets by putting a quad or two behind it, while my old diesel K5 wasn't any slower than normal with a couple quads behind it and a bunch of camping gear inside of it, and it always got good gas mileage.

If the diesel is in good shape, you can get it to perform similar to a stock mid 80s 350 by turbocharging it, but expect to spend a bit of money on the turbo stuff to do the swap.

$750 bucks for a full running and driving truck is a great deal in itself, so if you need a good truck, I'd say to go for it!

72freak · 07-06-2007, 10:24 PM

One of the least favorite of all the diesels EVER made!!!

79Silv4x4 · 07-06-2007, 10:40 PM

Quote:

Originally Posted by 72freak

One of the least favorite of all the diesels EVER made!!!

Yeah, but diesel was cheap back then! They are great for fuel economy but power sucks--unless you do the turbo upgrade like russell indicated. But even then it's nowhere near a modern diesel. Lastly, for $750 for a complete running truck the argument is done--BUY IT!

1984Silverado4x4 · 07-06-2007, 11:02 PM

There not like GMs 350 diesels are they?

BIGCHEVYMAN · 07-06-2007, 11:16 PM

No they are not like the 350 diesel, The 6.2 is a good little engine. My crew cab 4x4 has a 6.2 with a 4 speed and i just drive it 855 miles towing 6500 pounds and top speed was about 65 mph.

If you need a truck that is pretty cheep to operate this would be a great truck. espically when you notice the fuel mileage you are getting.

Curly86 · 07-06-2007, 11:19 PM

Yes they r a friend of mine has an 85 with one in it

Russell · 07-07-2007, 12:15 AM

A lot of people talk bad about "GM" diesels, but most of those people are just repeating hear-say, and have never actually owned a 6.2 or 6.5 diesel before.

Its true that the actual GM diesel, aka olds 350 diesel, was a real piece of crap, and rarely made it more than like 30 000 miles. They are so unreliable becuase they basically converted a gasoline engine to a diesel engine, which simply didn't stand up to the pressures of a running diesel engine.

The 6.2 and 6.5 diesels are not in fact GM made diesels, they are Detroit diesels. If they are run like a medium or heavy duty diesel engine they can, and do, break under the pressure.

They have a habit of breaking cranks if the harmonic balancer isn't replaced when necessary, and occasionally crack along the main webbings as well. Heads are also prone to cracking between the valves on the rear cylinder, but it rarely makes it to the water jacket if the engine isn't abused.

Overall, reliable engine for daily driving, not good for frequent heavy towing, and don't even hold a candle to how the modern diesels perform.

1984Silverado4x4 · 07-07-2007, 09:44 AM

Ok thanks guys

72freak · 07-30-2007, 04:57 PM

[QUOTE=Russell;2253668]A lot of people talk bad about "GM" diesels, but most of those people are just repeating hear-say, and have never actually owned a 6.2 or 6.5 diesel before.QUOTE]

Yep...........above is VERY correct!!!!!!!

BUT...........they got that reputation some how. I am one of the ones who have owned more than my share and have had bad luck in some form or fashion with all of them.

Thats not to say they were all bad.......its just the laws of averages the Im going on!!!

Pyrotechnic · 07-30-2007, 05:51 PM

The good thing is that parts for these motors are a pretty good deal. The injectors and injection pump are reasonably priced.

I wouldn't mind a mechanical injection 6.5 Turbo and a NV4500 5 speed.

1984Silverado4x4 · 07-30-2007, 09:38 PM

my brother ended up buying a 1984 Scottsdale for $500 instead cause we knew it was in good shape

07-06-2007, 06:23 PM	#1
1984Silverado4x4 Registered User Join Date: Jul 2007 Location: Mount Horeb WI Posts: 179	Info on a Diesel my brothers looking at a 1986 GMC with the 6.2 diesel and a 4spd in it. How reliable are these diesels. The guy wants $750 for it and says it runs great. from the outside it looks alright we havent looked close at it yet. Do you think it would be worth buying? __________________ Its no disgrace being poor. Its just inconvenient.

07-06-2007, 10:03 PM	#2
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Re: Info on a Diesel If you don't except it to pull like a Cummins, or accelerate like a modern Powerstroke / Duramax, those 6.2L diesels are pretty reliable little engines. They are classified as light duty diesels, and are not designed with towing in mind, just getting great gas mileage in a daily driver. I'd put one at similar acceleration to a 4.3L V6, but with tons more torque. My 4.3L truck is bogged right down and looses the gas mileage it normally gets by putting a quad or two behind it, while my old diesel K5 wasn't any slower than normal with a couple quads behind it and a bunch of camping gear inside of it, and it always got good gas mileage. If the diesel is in good shape, you can get it to perform similar to a stock mid 80s 350 by turbocharging it, but expect to spend a bit of money on the turbo stuff to do the swap. $750 bucks for a full running and driving truck is a great deal in itself, so if you need a good truck, I'd say to go for it! __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap) Last edited by Russell; 07-06-2007 at 10:05 PM.

07-06-2007, 10:24 PM	#3
72freak Rottenwood Garage Member Join Date: May 2005 Location: Marietta, Georgia Posts: 4,321	Re: Info on a Diesel One of the least favorite of all the diesels EVER made!!!

07-06-2007, 11:02 PM	#5
1984Silverado4x4 Registered User Join Date: Jul 2007 Location: Mount Horeb WI Posts: 179	Re: Info on a Diesel There not like GMs 350 diesels are they? __________________ Its no disgrace being poor. Its just inconvenient.

07-06-2007, 11:16 PM	#6
BIGCHEVYMAN Senior Member Join Date: Apr 2002 Location: Portland , Tennessee , United States Posts: 1,024	Re: Info on a Diesel No they are not like the 350 diesel, The 6.2 is a good little engine. My crew cab 4x4 has a 6.2 with a 4 speed and i just drive it 855 miles towing 6500 pounds and top speed was about 65 mph. If you need a truck that is pretty cheep to operate this would be a great truck. espically when you notice the fuel mileage you are getting.

07-06-2007, 11:19 PM	#7
Curly86 You want it there when??? Join Date: Oct 2006 Location: Lewisburg Ky Posts: 393	Re: Info on a Diesel Yes they r a friend of mine has an 85 with one in it __________________ 1986 Silverado Flatbed 400 SB with 350 turbo 1997 Ford Explorer with 302 mydrive to work ride 1978 Gmc Midas RV 21ft with 46,000 actual miles 2003 Chevy Avalanche 5.3 327 and Tweety Bird Yellow Big Sandy Survivor 09 Trucks in the Blue Grass Survivor 09 TNCTC Streetcruzin

07-07-2007, 12:15 AM	#8
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Re: Info on a Diesel A lot of people talk bad about "GM" diesels, but most of those people are just repeating hear-say, and have never actually owned a 6.2 or 6.5 diesel before. Its true that the actual GM diesel, aka olds 350 diesel, was a real piece of crap, and rarely made it more than like 30 000 miles. They are so unreliable becuase they basically converted a gasoline engine to a diesel engine, which simply didn't stand up to the pressures of a running diesel engine. The 6.2 and 6.5 diesels are not in fact GM made diesels, they are Detroit diesels. If they are run like a medium or heavy duty diesel engine they can, and do, break under the pressure. They have a habit of breaking cranks if the harmonic balancer isn't replaced when necessary, and occasionally crack along the main webbings as well. Heads are also prone to cracking between the valves on the rear cylinder, but it rarely makes it to the water jacket if the engine isn't abused. Overall, reliable engine for daily driving, not good for frequent heavy towing, and don't even hold a candle to how the modern diesels perform. __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

07-07-2007, 09:44 AM	#9
1984Silverado4x4 Registered User Join Date: Jul 2007 Location: Mount Horeb WI Posts: 179	Re: Info on a Diesel Ok thanks guys __________________ Its no disgrace being poor. Its just inconvenient.

07-30-2007, 04:57 PM	#10
72freak Rottenwood Garage Member Join Date: May 2005 Location: Marietta, Georgia Posts: 4,321	Re: Info on a Diesel [QUOTE=Russell;2253668]A lot of people talk bad about "GM" diesels, but most of those people are just repeating hear-say, and have never actually owned a 6.2 or 6.5 diesel before.QUOTE] Yep...........above is VERY correct!!!!!!! BUT...........they got that reputation some how. I am one of the ones who have owned more than my share and have had bad luck in some form or fashion with all of them. Thats not to say they were all bad.......its just the laws of averages the Im going on!!!

07-30-2007, 05:51 PM	#11
Pyrotechnic Registered User Join Date: Feb 2007 Location: Austin, TX Posts: 3,930	Re: Info on a Diesel The good thing is that parts for these motors are a pretty good deal. The injectors and injection pump are reasonably priced. I wouldn't mind a mechanical injection 6.5 Turbo and a NV4500 5 speed.

07-30-2007, 09:38 PM	#12
1984Silverado4x4 Registered User Join Date: Jul 2007 Location: Mount Horeb WI Posts: 179	Re: Info on a Diesel my brother ended up buying a 1984 Scottsdale for $500 instead cause we knew it was in good shape __________________ Its no disgrace being poor. Its just inconvenient.



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