any chance you have a photo of the two belts rib's?

well i'd list all the components in the equation that were changed prior to this starting, then do as you're doing and change back to rule out what it isn't.

as for the belt, if a company changes it's production sure it could be the issue. but you'd expect to hear a lot more feedback/chatter if that were the case. it's more likely something perhaps installed a little off or cheap product in the mix causing it. i'd look at URO before Contitech (Continental Tire).

 

When does it squeak? I chased what I could have sworn was a belt squeal for almost two years, replaced belts and pulleys multiple times, tensioner etc. believe it or not the squeaking noise turned out to be coming from then airbox mounting bolts, which is why it would go away for a short period of time anytime I messed with the belts as that had to come off to gain proper access.

Mine would squeak at low rpm under load or with quick throttle blips.

I lubed the bolts and surrounds and it has not come back in over 3 weeks, I did not touch anything on the belts so I know this had to be it.

Good luck,


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I'll try and get a photo of both belts soon. It could be that the old belt's ribs are worn which is why they look smoother/cleaner than the new belt.

I initially thought that maybe Contitech was getting bad with quality control, but there's a good possibility that the belt and the URO pulley didn't work well together. It and the OEM pulley looked identical but I've been wrong before lol. It only squeaked on cold starts and would do it regardless of how hot/cold or wet/dry outside conditions were. I tried washing the parts thinking grease/grime may have gotten on the pulleys, and no squeaking when wet, but as it dried it slowly came back. So far I've started the car a few times and no squeaks with the old belt installed.

I had the same issue with my airbox bolts last year, RG. Luckily the sound resonated more on the diver's side instead of in the center. Greased the bolts/speed nuts and haven't had a problem with them since. With them, it was the exact opposite. The airbox bolts would squeak at low RPM after driving for some time, while the belt would squeak at start and go away after driving.

 

Reviving an old thread. I did some significant work in the past couple of months (new axles, front wheel bearings, oil pan gasket, etc). As part of that I checked and replaced my idler & tensioner pulleys. I had noticed a "squeak" when the engine was started from cold, but the noise always went away when warmed up - usually before SAP quit. Now that it is cold (below 15 F), that noise has come back. I isolated the noise with a piece of silicone vacuum hose as my one-ear stethoscope (CAREFUL). It is mostly / all at the WP pulley area.

I investigated and tested - sure enough, the noise disappears with a little washer fluid (it's below freezing here) on the belt grooves. If I add lots of fluid I can make it briefly squeal, then it goes silent, then it will make the squeak (chirp) again, until it finally warms up. The belt is not brand new, but should be in its prime of life. It is a Continental, not BMW branded. I have an Uro WP metal pulley, so that could be part of the problem, but the pulley runs true and is well machined. I plan to try out both a new Contitech OEM style belt (what I have now, but new) and a Continental Elite ('Gatorback' design) belt in OEM lengths. I will report back when I can try all three back-to-back. Until now I didn't suspect that a slight difference in belts could make a periodic squeak or chirp. I found someone on a corvette forum who replaced seriously expensive hardware before he discovered the belt brand was the issue.

Mariner05

 

Did my cooling system refresh about 3 weeks ago and running Contitech belts and so far so good no noise and smooth.

 

Just bought Contitech belts for my daughters A4 Quattro, timing and serpentine, but I don't have to listen to it.

 

Humm - in 15f weather - the metal pulleys shrink and the rubber belt is harder - so a slip or chirp before things warm up might not be that unusual - I've never had issues with gates or conti belts - perhaps tensioner doesn't like the cold ? Not sure if a belt "dressing" would help - but that might be a cheap fix to try

 

If you have a Wahler thermostat... check to see if it is leaking coolant from the electrical connector.
It could be leaking onto your belts and squeaking.
Happened to me. Now I have a Mahle/Behr with no squeaks.

 

No leaking going on.

Received the first of the new belts today - Contitech regular style belt. Put it on and chirp is gone, that's at -1 F. When the Contitech Elite (Gatorback) comes I will just hang it up in the garage until (if) I get the chirping back. The old belt has no cracks, no glazing - but the new belt has the 'fuzzy look' that is worn off the old one, and that might be the key.

Mariner05

 

I used contitech also and they work perfectly. no slipping, noises, or unusual wear.