Need help identifying noise!!

[Barc]

I know I have been on here before asking for help with an annoying noise but I'm back!! It sounds like it is coming from the engine compartment somewhere and it makes the same sound as a shot out bearing rattling around - it is intermittent (not constant) It seems to be worse before the vehicle warms up and it is NOT the turbo - I know what it sounds like - this truck DID NOT make this noise for the first 9 months of it's life - and now it does!! It is a new and annoying noise - I just wish whatever it was would fly apart or just STOP!! If anyone has any ideas I would appreciate them - I, along with my service department, are all out of ideas!! Thanks

[mackin]

Barc,

Your just a tad bit vague for some real answers to your problem......
My assumption is it is an engine sound while running? Accelerating? Sounds like perhaps the pilot injection....Does it sound like a loud diesel clatter? I'm just taken a stab in the dark here .......I could be way off base......But trying to assist.....

MAC

[Barc]

Sorry Mack - I'll try to explain it a little better!! It is an engine noise - it is more noticeable when accelerating but I can still hear it at idle and when cruise is set - last week it went away completely for about a 10 minute stretch but unfortunately it returned. It is hard to explain and maybe that's why the service department isn't having much luck either - it almost sounds like a cross between radio static and a shot out bearing rattle - if you hit a bump in the road it disappears for a split second - at one time I thought it might be turbo or tranny related but the dealer is leary about tearing into either one - clear as mud????

[afp]

Barc,

It sounds like you might have the "tick."

Blaine

[mackin]

Well this is what the tick sounds like
=>http://www.csimo.com/junk/duramax_ti...ick_noise3.wav

But I doubt that is it for I have never heard it other then at idle.....Seems you probably have a bad bearing some where in the serpentine belt accessory...Could be the tension'er (spelled right?) a few have failed.....Intermediate problems are hard to diagnose .......Good luck.....

MAC

[gun runner]

Barc - had a similar noise ;mounting bolt behind power steering pulley worked loose. Finally fell out and bounced around inside the pulley so loud ,the dealer had to fix the noise.

[RRHOGGER]

NVH problems are very often difficult to diagnos when you are with the machine and practically impossible "over the phone" When you say the sevice department do you mean yours or the GM dealer. They have technicians that specialize in NVH and the dealer is obliged to fix the problem.

Hog

[TopBanana 2500]

It almost sounds to me like a slight exaust leak when cold. Then quiets down when warm, except when quickly accelerated.??
Just a guess from a struggling do it your-selfer

[Barc]

Thanks for the replies guys!! I have narrowed it down (in my own mind) to one of three things - tranny, turbo or exhaust!! I'm leaning towards the tranny - it seems to come from right in front of my feet, possibly right under my feet - what, if anything, moves and would make a rattling/whistling type noise in the tranny????

[DmaxMaverick]

Barc

Check your turbo downpipe brackets. Look in the passenger side wheel well, pull back the liner at the rear and you should see at least one of the bracket ears. I've heard of and seen (including mine) a few that have verticle cracks. Some have made noises, some don't. Mine was silent. The repair was a simple weld about 15K ago.

Other than that, check out all your plumbing (tranny lines, A/C lines, intake pipes, etc.) to make sure nothing is chafing. Good luck.