Dribble a little water on the smooth back side of the belt while the noise is occurring. If the noise changes, check the spring-loaded tensioner to see if it is sticking and not putting enough tension on the belt, and check for pulley misalignment. Typically that will also be caused by a worn pivot for the tensioner pulley. If the belt is off-center by as little as 1/8" on any pulley, that will cause it to slide sideways across it as it goes around it.

Based on your observation that the noise stops in short order, it's more likely to be a tension-related problem. Some engines use a separate belt for the AC compressor. Be sure to check that one for proper tension too.

Answered by caradiodoc (expert)
17,308 answers provided

Thanks for the quick response caradiodoc. This gives me a good idea of what I'm looking for.

Response from ibpraline
2 questions asked

Just a FYI. Lots of early to mid 2000s OEM Toyota factory serpentine or drive belts that comes with the car new has a defective design that causes squeal noise during cold start up. I have replaced 2 Toyotas I own with the Goodyear Gatorback belts and the squeal noise is no longer there during cold startups.

Answered by sumac0401
3 questions asked