Chevy 6.5L diesel - why so bad?

[Fordiesel69]

Honestly the RPM's he was running it during the testing should not have killed it. What is it with these 6.5L that they are so fragile? I had seen these blow down at our state auction many times during a cold start. Usually because of starting fluid.

I thought these were made in part with Detroit diesel and were actually fully engineered as a diesel from the ground up, and that they do not have gasoline similarities that caused weakness like 350 chevy diesel..

 

[wwillson]

I thought these were made in part with Detroit diesel and were actually fully engineered as a diesel from the ground up, and that they do not have gasoline similarities that caused weakness like 350 chevy diesel..

The 6.2 and 6.5 were both Detroit Diesel engines. The 6.2 couldn't pull the hat off your head, but it was reliable. From what I understand the 6.5 had casting problems that caused a lot of broken cranks. I'm sure others know more of the story.

 

[fantastic]

Apparently it took around 20 years for GM to dump DD in favor of Isuzu manufacturing. But all the first light duty diesels were prone to issues. I just did some reading up on them again under "Common Problems" listed below. The 6.6L was finally the competition they were striving for.
https://en.wikipedia.org/wiki/Detroit_Diesel_V8_engine

 

[MrHorspwer]

Honestly the RPM's he was running it during the testing should not have killed it. What is it with these 6.5L that they are so fragile?

For the truck in the video, there's obviously something wrong with it.

Having abnormal combustion events beat the hell out of the rotating assembly for who knows how long, then having it all fail when it begins to free-rev to the moon isn't really an indicator on fragility. Mis-time the combustion on any engine and you'll find a failure real quick.

I was at a GMC dealer when the 6.5L was the diesel option: Pump-mounted drivers all day. I can't really comment on longevity outside of when people would bring them back to the dealer for service, but that's what kept our diesel tech busy in the warranty period.

 

[dfarr67]

They had their issues but I don't think they were a bad engine, certainly not great tho.

 

[supton]

Detroit Diesel seems strange to me. They figured out the 2 stroke in the 30's and then... what? Just kept making bigger and bigger 2 strokes? Took them a while to figure out the 4 strokes.

Caught a vid last week about the DD 8.2L V8 and it was rather negative about that engine. Forget what it had for problems, too few head bolts, rods too short and thus fast cylinder wear? something like that.

Have to say, the 6.2 goes back to some darker times for power and economy. Meant to be a light duty diesel, back when 55mph was the limit, and people didn't expect to tow at 75mph up Ike's pass. Today they seem about useful as VW's 1.6 IDI (remember those? in the Rabbit and Caddy? slow ride indeed).

 

[CheezWhiz]

I heard those Oldsmobile 350 diesels were pretty sweet.

 

[JHZR2]

I had seen these blow down at our state auction many times during a cold start. Usually because of starting fluid.
..

Starting fluid shouldn’t be used in IDI diesels with glow plugs…

 

[JHZR2]

Honestly the RPM's he was running it during the testing should not have killed it. What is it with these 6.5L that they are so fragile? I had seen these blow down at our state auction many times during a cold start. Usually because of starting fluid.

I thought these were made in part with Detroit diesel and were actually fully engineered as a diesel from the ground up, and that they do not have gasoline similarities that caused weakness like 350 chevy diesel..

I couldn’t watch this whole thing, but the whole idle rising thing is easy. If a linkage is sticking, or slow to respond, the return to idle will go slowly, and the engine will overreact when unloaded. Cruise control actuators will be a common culprit.

He says it’s interesting and challenging. I doubt it. This one is easy imo.

And he may change parts, but in removing and reinstalling/lubricating stuff coukd be the fix, while attributed to some part they threw at it…. From what I watched, that’s what he did. Two control chips, no change, too much overrevving, poor diagnosis.

 

[atikovi]

If a linkage is sticking, or slow to respond, the return to idle will go slowly, and the engine will overreact when unloaded.

No linkage, drive by wire.

 

[atikovi]

What is it with these 6.5L that they are so fragile? I had seen these blow down at our state auction many times during a cold start. Usually because of starting fluid.

Have one in a '92 Chevy truck that had a reman engine put in before I got it, but don't know when or why. Does run nice. Using starting fluid if you don't know what you're doing is asking for trouble. Spray too much and it lights off half way up the compression stroke greneding the engine.

 

[cptbarkey]

I couldn’t watch this whole thing, but the whole idle rising thing is easy. If a linkage is sticking, or slow to respond, the return to idle will go slowly, and the engine will overreact when unloaded. Cruise control actuators will be a common culprit.

He says it’s interesting and challenging. I doubt it. This one is easy imo.

And he may change parts, but in removing and reinstalling/lubricating stuff coukd be the fix, while attributed to some part they threw at it…. From what I watched, that’s what he did. Two control chips, no change, too much overrevving, poor diagnosis.

He is usually really good at diagnostics, the engine already sounded terrible in the beginning of the video (51-53 seconds in) unfortunately.

 

[ripcord]

The Detroit's had a problem where the rubber isolaters in the crank dampeners would degrade and the outer balancing rings would walk around and throw the cranks out of balance. This is often attributed to some cranks breaking. A common upgrade on these is to replace the factory dampners with aftermarket ones.

 

[Chris142]

I had a customer that had a truck with that engine. He said he had 5 engines under warranty. The main journals crack last I heard.

 

[wwillson]

Using starting fluid if you don't know what you're doing is asking for trouble.

Using starting fluid in any diesel is dangerous at best.

 

[JHZR2]

No linkage, drive by wire.

At the injection pump? Way different than gas engine. My Cummins of the same era has linkages behind the IP.

A gunky control cable could do the same if the return springs/actuators aren’t right.

 

[Brons2]

The 6.2 and 6.5 were both Detroit Diesel engines. The 6.2 couldn't pull the hat off your head, but it was reliable. From what I understand the 6.5 had casting problems that caused a lot of broken cranks. I'm sure others know more of the story.

The aftermarket Optimizer blocks fixed the 6.5 issues, but they don't come cheap. Drop in is over $11K from these guys:

C/K Series Pickups and Suburban – 6-5 Liter

www.6-5liter.com

there's long blocks also, only about 8K on those.

There was a guy on here who put one of these Optimizer blocks in his 1999 Suburban based on poor oil analysis. It's out there if you do a search.

 

[wwillson]

There was a guy on here who put one of these Optimizer blocks in his 1999 Suburban based on poor oil analysis. It's out there if you do a search.

GM 6.5L; Rotella T6 5w-40; bearing problems?

Thanks for the moral support. It's a great running truck. Chevy/GMC hasn't made a diesel Suburban since 1999 and stopped making the heavy duty 3/4 ton with the last generation that ended a couple years ago. So you can't really tow a car trailer with them any more. We are keeping it forever...

bobistheoilguy.com

 

[ripcord]

Using starting fluid in any diesel is dangerous at best.

I used an old track loader on a job site once that had a button on the dash labeled "Ether," so at least some diesel rigs were ok with it. Probably not ones with glow plugs, though

 

[wwillson]

I used an old track loader on a job site once that had a button on the dash labeled "Ether," so at least some diesel rigs were ok with it. Probably not ones with glow plugs, though

Yes, that is true. Many diesel farm machines have ether injectors for cold starts, none of those have glow plugs. If you use a tiny bit of ether, you normally don't break piston or piston rings. Unfortunately, the belief seems to be if some is good, then more is better. I have personally seen many broken piston rings and cracked pistons from over use of ether.

We found the best method is to squirt a very small amount into the air cleaner and the machine would start without the banging of the extremely fast pressure rise pounding on the top of the pistons. If you use the injector that sprays directly into the intake manifold, you'll get loud banging practically every time.

If you hit the top of the piston with a hammer enough times, you're going to break it. We absolutely will not use the ether injectors.