Hi, My '03 is chirping pretty good. All efforts to date have been unsuccessful in tracking it down. Any one here have a sucessful repair?
So far: Noise appears on startup, goes away after warmup.
The shop changed out the drive belt, probaby to Gates brand, sound disappeard for a week. I swapped out what appeared to be a bad idler pulley. The problem has not been corrected. Today, the shop mechanic swapped out the other idler pulley, examined the tensioner and other pulleys as well as the belt. Belt dressing eliminates the sound for ten seconds or so, then it would return (often louder). He couldn't isolate a bearing noise with a stethascope or otherwise diagnose it in 1.5 hours. A search through TSB's comes up with a) swap out the belt and B) swap out the belt to an alternate GM belt #.
I couldn't hang around for a delivery from the GM dealer, so I'll get the replacement belt myself.
Thanks for listenin'!

This is just another one of those things where I will give you my opinion and what I have doen in the past to correct this issue from something an old timer told me years ago. The grooves in the belts do not always line up perfectly, and they get burnished as they run at RPM, thus causing the "chirp" as the metal and rubber meet misaligned just ever so slightly. What I was told to do and have done on occasion with success is to take a piece of 60-80 grit sandpaper wrapped around a paint stick, tightly and taped on one side, then as the motor idles I gently touch the sandpaper to the grooved side of the belt holding it at an angle that won't shoot it back at me if it happens to grab (note touch lighlty to belt) and then as it slips over the sandpaper I gently add pressure, just a little, until the chirp goes away.
JMO but it has worked for me in annoying situations. Best o luck to ya.

I had basically the same symptoms and it was my alternator bearings going out. i had already done the belt/idler pulleys :cool:

Yeah, I dug into the archives. Not an uncommon problem, especially with the LLY and later - pops up in new trucks too. Pulley misalignment seems to be the most likely cause. Success has been reported by some by 1) sanding the belt (backside on all the ones I saw - Yours is the first I've seen addressing the grooved side lancerdually... not a statement of value mind you); 2) a different alternator bracket from GM; 3) seating the powersteering puller deeper; 4) running gatorback belts 5) thourough cleansing of the pulley grooves and surfaces and 6) suffering.
Thanks!

i have used wd-40 to diagnose pullies.not saying thats it but it will identify bad pullies.spray and saturate 1 pulley at a time it will shutup when you hit the right one.it will also temporarally take care of the belt.if it is the alternator,wd really doesn't make it to the bearing.hope this helps.

It could just be moisture, especially since it goes away after warmup. Mine does that if the humidity is high, or after a rain storm or car wash.

The Duramax makes all kinds of wierd noises on occasion. It's a diesel engine and has a lot of stuff going on. When my trucks make wierd noises I run the crap out of it until it go's away:D. At the last sled pull my truck made some noises that were very ugly.
All kidding aside. A belt chirp is a normal thing with a high compression engine. You need to do some 4 wheel boosted launches, once and a while:eek:

my belt always make nice sounds when its wet!

Did I just get "barbed" for my statement? Oh my, oh my.

Did I just get "barbed" for my statement? Oh my, oh my.
what's barbed?

Yeah, I dug into the archives. Not an uncommon problem, especially with the LLY and later - pops up in new trucks too. Pulley misalignment seems to be the most likely cause. Success has been reported by some by 1) sanding the belt (backside on all the ones I saw - Yours is the first I've seen addressing the grooved side lancerdually... not a statement of value mind you); 2) a different alternator bracket from GM; 3) seating the powersteering puller deeper; 4) running gatorback belts 5) thourough cleansing of the pulley grooves and surfaces and 6) suffering.
Thanks!

Not sure if that was meant to say my statement had no value or what. LOL Why I asked if I got "barbed". ie...jabbed at, ripped.:confuzeld

my truck is 1500 miles away so i can't look at it but, i think the idler pulley is the only one that touches the back side,and they normally don't have a 90 degree edge,so the misalienment? can only be on the grooved side.if that's the case,someone barbed themself.if you have used your method and it worked,you have added value to this thread.

Yea mine touches on the grooved side in many places like the alt, a/c, fan and etc. And I ain't even sure if the method I have used would fix the problem? I do know it's worked for me and I just posted it to help. Hoping when I run into a problem I don't understand and ask on here about it, I'll get any and all info people have on similar issues. Opinions are like @$$&@!*$ and I am danged glad to hear any and all that may help me figure a problem out any time.

lancer,that's a good attitude.if sanding the "non grooved" side helped someone else,the belt must have been slipping on the idler,not a drive pulley.:confuzeld but what do i know.they are grooved for a reason=grip.

Uh oh, I guess I must have mistyped what I was trying to say originally. I meant to sand on the grooved side. Dang my east tx redneck brain and fingers.
Sorry if I was misunderstood.

Had to take time off this thread to get my injectors done:P I replaced the drive belt (P/N XXX30) with the GM alternate service belt (P/N XXX28) and the chirp is gone now (500 miles?). Time will tell. FWIW, the back side has a lightly checkered surface.

I had exactly the same problem and did the normal stuff of replacing the belt and then the idler pulleys, no help. The tensioner seemed OK but I replaced it anyway to make sure and that fixed the problem. I guess if the spring rate in the tensioner gets just a bit weak it will cause the belt to slip a little giving you the different noises. I got a tensioner from Advance Auto because they were the only ones who had it, but it wasn't very expensive.