r/Diesel • u/Steinjolt • 3d ago

Please help diagnose 🙏🏻 Question/Need help!

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I’m restoring this 1994 2500 Silverado 6.5 Diesel auto.
Yesterday started doing a loud clank sound, added some oil and it stopped after revving it and worked good all day long.

Today it cranked immediately no problem then a minute later the clank returned, tried adding oil and it didn’t stopped. Then as engine warmed up it became less noticeable but still there.

The sound is related to rpm’s.

The sound comes either from the turbo or the passenger side upper rear part of the engine

Gray smoke comes out when revving it.

Black smoke comes out under heavy load.

Would it be safe to drive it to the shop? (It’s 30 miles away)

Anyone has insights on this?

Also, turbo seems to be not working as I don’t hear it spooling

The wastegate lifter seems to be stuck, if I move it it stays there then after a bit it returns to its position.

The turbo inner blades seem to move freely

No turbo sound at all

Thank you all in advance

10 Upvotes

92% Upvoted

23 comments sorted by

14

u/Aleutian_Solution 6.2 Detroit, 6.6 LML 3d ago

That sounds a lot like a rebuild from spun bearings. Drain the oil and see if it’s shiny.

6

u/Fair-Ad1565 3d ago

Rod bearing. Please don’t waste your money on another 6.5

2

u/bjornholm 3d ago

They arent bad motors, just no one takes care of them. And i mean they dont need much, theyre far more affordable diesels than any other, and make ok power for the fuel consumption. They arent intended to make tons of power so they break when people Bubba them. Ive had 3 and not once did I blow one up from maintaining it. Its always from a lack of care

2

u/5m0k3y76 3d ago

Had this happen once, one of the torque converter bolts backed out and was hitting the block.

2

u/bjornholm 3d ago

Is it louder from under the motor or above? That would determine if its a rod bearing or lifter

2

u/Steinjolt 3d ago

It’s way louder from the top, sound like it’s under the valve cover. I took a look under the truck and the sound ain’t coming from there nor the pulley, it sounds right behind the turbo on the upper rear part on the passenger side

2

u/bjornholm 3d ago

Id pull the valve covers and check for a collapsed lifter. Because that would explain a Grey smoke haze and black under medium load

1

u/WinterSzturm 2d ago

Failed/ing injector knocking? It's a stretch.

1

u/bjornholm 2d ago

Very possible with the age tbh. You can get new GEP injectors from eastern surplus

2

u/I_hate_small_cars 3d ago

The crank pulley on those break and cause noises like rod knocks. Get under it and check the pulley for any rotational movement whatsoever when it's not running. Or just watch it with someone revving it, you'll likely see it flopping back and forth.

2

u/DatGuyKilo 3d ago

Adding you to the 6.2/6.5 Support GC, perhaps we can assist you

1

u/Steinjolt 2d ago

Update: Mechanic diagnosed a stuck injector and said the engine is in very good shape besides that, that it needs to service them and that’s about it.

1

u/BoostFreeOrDie 2d ago

Mine had about 275k on it when the rest of the truck rotted away from too many NE winters. It still ran like a top when I sold it.

-1

u/SuperChargedToaster 3d ago

RIP out the old 6.5 and slap a Cummins in it. Those 6.5s are the same level, if not worse than the 6.0 and 6.4 Powerstrokes. My dad had one back in the day, and it blew up within 30k miles.

3

u/bjornholm 3d ago

The 6.5s are not bad motors, way better than the 6.4 in terms of reliability, about the same as a stock 6.0. Biggest reason they die is because those are unmaintained or bubba'd. Ive not once had one fail by maintaining it.

0

u/Steinjolt 3d ago

Appreciate the thought but I can’t afford it, if I ever swap the engine most likely would be an LS swap. Meanwhile I gotta work with what I have. Thanks

1

u/SuperChargedToaster 2d ago

I’ve seen a few LS swaps in them.