HBsurfer

2007 base, A6, Z51, 27,000 miles:
I replaced the harmonic balancer with an ATI unit and replaced both belts with AC Delco. All pulleys felt fine. Seemed to have grease in them and rolled smoothly.
When I start the car, hot or cold, it is silent for about 5 seconds and then I get a loud chirping for about 15 seconds. After that it is chirping but not as loud. It also seems to go away completely for a few seconds every once in a while. Everything looks like it is lined up properly. No wobble anywhere.
Is there any way to isolate where the noise is coming from without just replacing pulleys? I have been told to spray the pulleys one at a time with WD40 and when it quiets the chirp I will have found the culprit. Spraying the belt/pulley area with WD seems wrong to me. If that is the way to do it, let me know. I wanted to check in here before I did anything stupid. Any suggestions would be appreciated.

Kenny94945

Well you can try using a stethoscope to listen.
I have done the WD40 technique myself with no ill effects.

Could be oily residue on the pulley groves so the belt is slipping...contact cleaner and wire brush all the pully grooves.
Or a tensioner or belt pulley quide is bad even though they felt OK.

Good hunting.

AzMotorhead

I take it you've run it without the belts on it to make sure its a belt or pulley?
I've had a bad cam/lifter sound like a chirp

HBsurfer

I did run it without the belts. Should have mentioned that in the original post

old motorhead

Try to simulate a side load on each individual pulley. Put the belt on each pulley individually and pull back and forth. Even a pulley with a bad bearing will sometimes spin freely and quietly spinning it with no side load.

subfloor@centurytrans

Pour a little water on the belt while it's running. I've done this dozens of times on various cars over the years without having any issues.

timd38

I had that noise on another car and it was the water pump.

Take the belt off and see how the water pump turns.

Once I got it off the car the water pump was so tight, I could hardly turn it. I was surprised the belt hadn't broke!

cclive

I think spraying or pouring a little water on a belt is a better idea than WD-40.

MARSC6

When in doubt I normally try the long screwdriver against the ear trick.

HBsurfer

I tried water on the belts and it did not change. It is a strange thing. Silent after start up for the first 5 seconds or so, then very loud for another few seconds. After that, it is not very loud but definitely noticeable. I can hear it inside the car but I am listening for it. When I rev the engine a little it gets a little louder like the belt is slipping for a second or two and then goes back to a lower chirp. It also sounds like it is coming from the drivers side. Maybe I should just replace the three pulleys and see what happens.

timd38

Take the belt off and spin the alternator, water pump and PS pump, if any bind, you may have found the issue. Won't cost you anything to try.

timd38

Was the noise still there?

HBsurfer

Noise is still there. No change. I will take the belts off again and see if I missed something. The noise has been there for a long time (at least 4000 miles) with no changes. I have replaced the balancer and belts and it is still the same noise. No better. No worse. Had the belts off and checked all pulleys a couple of weeks ago and everything seemed smooth. I will do it again. The chirp is annoying and must be a sign of something going away but it has not become any worse. And the complete silence for the first five seconds or so after start up that gets very loud immediately thereafter is bizarre. That start up silence, loud chirp to moderate chirp is very consistent.

cclive

If you ran the engine without the belts, then it can't be any of the driven pulleys because they weren't turning.

HBsurfer

I was not clear there. Without belts, the noise is gone. I am just trying to see if there is a way to pinpoint which pulley or accessory is making the noise. Not having any luck so far. Worst case is I will just start by replacing the idler pulleys.

cclive

OK, I understand. I would try an automotive stethoscope before throwing parts at it. I would expect that you could help pinpoint the noise that way.

HBsurfer

Two roll always full of tools and no stethoscope. I will get one tomorrow and let you know what I find. Always fun to buys tools!
Thank you all for the help.

cclive

Another thought...the speed of the chirping should be noted also. Normally chirping from the belt goes at the speed of the belt...once per belt revolution. A chirp from a pulley should go at once per rev of the pulley, which would be maybe 6 or 8 times as fast as the belt revolves. Might help diagnosis. And even a really good automotive stethoscope will be less than half of the price of one pulley.

Also, you might try pulling the belt off and turning it around 180 degrees. What the heck...

dentalfloss

What ATI harmonic balancer did you buy? Is it a underdrive pulley or etc. Is it possible you need a next size tighter belt.

HBsurfer

Pretty sure the belt is ok by looking at the tensioner pulley. Releasing all of the tension barely gets the belt off. A tighter belt would be too short.

The ATI unit I installed is part #ATI-917246 H/P 7.5 Super Damper Serpantine Series, Internal balance, 7.530" O.D.