Hello,

I have been hearing a loud clacking coming from an right side by the valve cover. It is a 2001 2500HD with Vin 1 -- RPO LB7. The Vin is 1GCHK29121E276530. It is all stock and has 80k on it. The noise is loudest when it is cold and a small load on it. It seems to be the #4 injector. I have been researching the service bulletin No.: 04-06-04-007B.
I have put a engine stethoscope on the injectors and valve covers and the rocker arms seem to have the correct sound.
I would like to get GM to change all the injectors change and it is the RPO LB7. I also see a lot of smoke out of the tailpipe when getting on it.
What need to be said and done to get GM to change the injectors?

Thanks, lee2001

Take it to the dealer. Sounds like you have an injector on the fritz. Probably sounds like a really bad lifter tap. GM will replace under warranty for 200,000 miles. If you have a good dealership, just tell them what you have observed and they will take it from there. It's best to find a dealer with a dedicated big truck shop.

Thanks, is seems like you have heard this before. I thought it was a lifter or rocker arm at first.:exactly:

Look at the thread that Top Hog posted called "Knock under load" maybe that is the case with your truck as well.

heard the same sound in our 01. started throwing the P0093 code. the truck is in the shop having all 8 replaced. it your not throwing any codes start with the simple thing FUEL FILTER.

Yes check the Knock under load thread.