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Duramax 6600 Discussion Forum for the Duramax 6600 Diesel Engine, including the LB7, LLY, LBZ, LMM & LML engine specific topics.

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Old 02-12-2011, 12:22 PM
Bill Brayman Bill Brayman is offline
Join Date: Feb 2011
Location: near Birmingham, AL
Posts: 2
Question LB7 Bad Injectors + Abruptly Tappet Sound

I have been running a 2002 Chev K3500 w/LB7 Duramax with some smoke from bad injectors. I had to shut down engine when abruptly there was a lot more smoke pouring out of the exhaust and at the same time, occasional tappet type noise coming from the engine. Sounded like something was hitting to underside of a valve cover.
I have now torn the engine down to the point that I have removed all eight of the injectors. While removing the injectors, number 1 cyclinder injector came out freely with its sleeve remaining on the injector. I found no other evidense of anything that might have caused the "tappet noise."

Question: Does anyone know what was causing the occasional tappet noise? I know the additional smoke has obvisiously come from the leaking bottom seal around the sleeve which was identified as loose when the #1 injector was removed. My concern is whether there may be a head gasket problem too or... there may be other sleeves still remaining glued in each injector hole that may be leaking too. None are in any way loose like the #1 sleeve.

Question: Do I go ahead and replace ALL the glued in sleeves besides the injectors or is the one loose sleeve the occasional noise maker?
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Old 02-12-2011, 12:36 PM
DmaxMaverick's Avatar
DmaxMaverick DmaxMaverick is offline
Join Date: Apr 2001
Location: CA
Posts: 11,881

Welcome aboard!

In all probability, the sleeve was unsealed when you removed it. This is not too uncommon, and it can be resealed, reliably (provided there's no indication of corrosion, erosion, or damage), or replaced. The remaining sleeves can (should) be resealed, primarily for peace of mind. I would.

The "tappet" sound was likely fuel injector knock. This sound can be anything from a light tapping (like a lifter/tappet), to a horrendous banging (sounds like a rod trying to exit the block), depending on the leak volume. If you had fuel contaminating the engine oil, the thinner oil can cause other engine noises, and lots of smoke or a big mess.

If you are considering a head gasket replacement, it will never be easier than right now. The new(er) gaskets are more reliable, and, you'll get a look into the cylinders to identify any damage that may have resulted from the bad injector(s), or signs of head gasket failure.
1985 Blazer 6.2
2001 GMC 2500HD D/A
2014 Chevy Cruze Diesel - Fabulous car, no problems at all, but sold Nov. 2016 @ 55K miles.
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