1981 Chevy 5.7 IDI Diesel

[artificialist]

I read some Olds engine FAQs back when I wanted to restore a 1970s GMC RV, and there are FAQs that also cover the diesel:
http://www.442.com/oldsfaq/ofedsl.htm

According to this article, oil changes every 3000 miles weren't good enough back then, 2000 mile oil changes were recommended by the people who have surviving Olds diesels. Modern oils might correct that problem, but I don't know for sure.

 

[bullwinkle]

Newer HDEOs are better than the SF/CC oils then, but 3-4K is still decent insurance if there's a lot of soot buildup, UOA would probably allow extending the OCIs. Early GM diesels just have many weaknesses, nodular iron crankshafts, weak head bolts, poor fuel filter/water separators, direct drive starters (as opposed to higher torque gear reduction), weak blocks, etc., etc. They will run, but don't confuse them with any HD diesel, or even a 6.9/7.3 Ford IDI-they're just not very durable.

 

[A_Harman]

The 6.2L IDI that GM introduced in '82 (or maybe '83?) was much better than the 5.7L Olds engine. Some DNA from that engine survives to the present day in the Duramax.

 

[bullwinkle]

6.2 started in '82, it had weaknesses too, blocks were weak (except for the first year, '82, & the '92-'93 599 blocks that were made thicker for the 6.5 TD), & they had the same weak nodular iron cranks as the 5.7. The 5.7 was basically a beefed-up Olds 350, the 6.2 was a new design from Detroit Diesel-but there were MANY teething pains & improvements for the 6.2/6.5. The Duramax was an Isuzu design, common rail direct injection, far superior to any older GM IDI. Now a new Peninsular Diesel 6.5, with a FORGED crank & beefed up block, would be decent.

 

[A_Harman]

I don't know if the Duramax was completely engineered by Isuzu, or if it was a collaboration between GM Powertrain and Isuzu. What I do know is there is a large group of engineers working in the Duramax group one floor down from me at GM Powertrain.

 

[dnewton3]

It's my understanding that Isuzu did all the mechanical design, and GM did the electronics package design for the Dmax.

Does not really matter to me; the end result is simply outstanding. Probably one of the best wearing, better running light duty diesels ever made. It, too, had a few teething issues at first, but no where near as bad as other GM diesels and some Ford/Navistars.

 

[Zaedock]

Originally Posted By: bullwinkle
The 5.7 was basically a beefed-up Olds 350,



This is actually completely untrue. The Olds gas/diesel look similar due to using the same tooling. That's about it.

 

[bullwinkle]

Actually, a common use for the diesel 5.7 is to convert it to a gasoline engine-one of the links posted above mentions it. The heads are different (precombustion chambers in the diesel), but the block will work as a gas motor.

 

[bullwinkle]

Also, if head stud sets (ARP for example) are still available for the 5.7 diesel DX, that would be a good investment. I've been tempted to put them on my '93, as it still has non-leaking good original head gaskets, but I'm not positive that I could get them all in with the engine in the truck. I had a '92 6.2 with 300K on it, so it is possible to get big miles on one (if not abused), with the correct mods & updates I would think a 5.7 would at least have a chance of making decent mileage.

 

[clinebarger]

A Olds 455 would have about the same cost of ownership as a Olds 5.7 Diesel. The 455 will at least put a smile on your face!

 

[A_Harman]

Originally Posted By: bullwinkle
Actually, a common use for the diesel 5.7 is to convert it to a gasoline engine-one of the links posted above mentions it. The heads are different (precombustion chambers in the diesel), but the block will work as a gas motor.


I remember Andy Mannarino built a pro stock drag car with the Olds diesel block.

 

[Astro14]

Originally Posted By: bullwinkle
Actually, a common use for the diesel 5.7 is to convert it to a gasoline engine-one of the links posted above mentions it. The heads are different (precombustion chambers in the diesel), but the block will work as a gas motor.


The blocks are similar - but larger head bolt sizes and a few other things have to be taken into account. That Olds diesel block would make for a very stout gasoline motor if properly set up...I read, a few years ago, that it's hard to get Olds diesel blocks for precisely this reason...

 

[bullwinkle]

Originally Posted By: clinebarger
A Olds 455 would have about the same cost of ownership as a Olds 5.7 Diesel. The 455 will at least put a smile on your face!
A smile on your face, & a BIG DENT in your wallet! I had a few BB GM cars in the day, couldn't afford to drive them then, either!

 

[bullwinkle]

Originally Posted By: Astro14
Originally Posted By: bullwinkle
Actually, a common use for the diesel 5.7 is to convert it to a gasoline engine-one of the links posted above mentions it. The heads are different (precombustion chambers in the diesel), but the block will work as a gas motor.


The blocks are similar - but larger head bolt sizes and a few other things have to be taken into account. That Olds diesel block would make for a very stout gasoline motor if properly set up...I read, a few years ago, that it's hard to get Olds diesel blocks for precisely this reason...
If it is a DX 5.7 engine, it's tougher than the older 5.7s were. I had an '85 C1500 Suburban for a while, 6.2 with 700R4 & 3.42 rear axle, it was capable of 23-24 MPG highway-a 5.7 would be even better, possibly 28.

 

[Dufus2]

My experience with this 5.7L diesel is the glow plug board going out and it would not start. These had 6V glow plugs (Intended to pulse) and people would go to a push button and burn out the glow plugs from overheating the tips.

I always ran 30W in this engine and there was never any breakdowns except for popping a head bolt or a failed injection pump. There was an issue with the starter going bad and some type of kickback that breaks the nose cone. I am also thinking the oil change was around 6-7 qts if that helps.

 

[Red91]

I like the Oldsmobile 5.7 Diesels and the Detroit 6.2/6.5 Diesels. They are interesting, and I'd like to own one just for fun.

 

[clinebarger]

Originally Posted By: bullwinkle
Originally Posted By: clinebarger
A Olds 455 would have about the same cost of ownership as a Olds 5.7 Diesel. The 455 will at least put a smile on your face!
A smile on your face, & a BIG DENT in your wallet! I had a few BB GM cars in the day, couldn't afford to drive them then, either!


I did BOP-C swaps in Chevy/GMC trucks quite often in the 80's & early 90's, More reliable than Chevy small blocks & big blocks, And usually better MPG. My '69 C10 got 13 mpg with a Cadillac 472/TH400, The original 396 got 8 mpg going downhill with engine off. The Olds 455 was a little better on fuel than the Cadillac engines at 15 mpg in a '67-'72 pick-up.

 

[another Todd]

I used to tow a fair amount of those from freeway on ramps. People would turn the corner then punch it to get up to speed and the crankshaft would break. Drive it with care and it will be decent enough, if you can stand the smoke and smell.