04 2500LD 6.0 4x4 crew cab (auto) 22000 miles

About two weeks ago noticed a loud tapping noise from the bottom end passenger side. Not the normal rattle of piston slap that I am use to on the 01 Tahoe. Seemed to go away after reaching driving temp.

Timed it yesterday. Start truck, not present at start up. Wait 2-3 min. Starts tapping. Gets louder. Loud enough to be clear at 100ft. Heard well over the normal engine noise. Drive for 20 min, seems to be gone.

Took to the dealer today. Told them to let it cool off and then start it. They waited until after lunch. Called me. Said they started it, waited, listened, and heard a slight tapping. Attributed to piston slap (carbon build up on pistons). Basically told me no issue.

They called back 15 min later and said, man now we here what you are talking about. They had let the truck warm up and it got loud enough that another service tech pointed it out in the lot to the service guy I was working with. They have a call into the service manager to see what he recommends. Waiting on a call back tomorrow. Truck drives fine. No issues that I can tell other than this noise.

Dad (old school gear head) said might be exhaust leak that is going away when truck warms up.

Today after taking to dealer, does seem to get quieter after warm up, but does not go away completely. Seems to change tone when going from Park to Drive to Neutral. Laying under passenger side, you would swear it is right above you.

Any guesses?????

Thanks

 

torn oil pump pickup tube oring? usually thats at lower mileage though. Let us know what they find

 

I had an 04 CC 6.0/4l80e 2wd come in that had a cracked flywheel on it. It sounded like the piston slap, but it changed when you put a load on it or just changing gears. Might want to ask them to check that.

 

cat. coverter bank 1 was my rattle

 

Took the truck in. Friday morning, the Regional SVC mgr heard the noise and said "Tear it down and find it". I was not thrilled, but I wanted it fixed. Monday morning, got a call, and just as Chevymec said the flywheel was cracked.....They replaced it and all is well.

When I picked up the truck, I wanted to see the fly wheel. CRACKED HELL!!!!. The center was almost broken out of it. Cracks all the way around all the bolt holes, and a crack from each bolt, out to the 2in holes that are cut in the flywheel. They said they would send it back to GM.

Well I am glad it is fixed, and I must say the level of service I got from Carl Black Chevy in Nashville TN was A++++++. They agreed with me that something was not right, they went up the chain to get permission to look for it, they kept me informed, and they fixed it.

Thanks again, Chevymec.

 

Wow, that's really strange. Any word on how it might have happened?

Glad it's all fixed though.

 

Sounds just like the flywheel I had. Glad I could help!!
I know it is a defective part cause the truck I fixed wasnt driven hard at all.