Screeching / Metallic Scrapping Noise
 

Hey guys,

I tried searching elsewhere but couldn't come find anything useful.

When it gets cold outside (starting around 30 ~ 35F), my car makes a metallic screeching/scrapping noise from under the hood. It sounds like nails on a chalkboard (literally), but from something that's rotating quickly and constantly. Seems to be coming from the belts area. The noise subside just a little once the car is warm but is still very audible. Also, whenever the car is in gear, it gets louder, but doesn't become any louder as I accelerate. When I fully depress the clutch, or the car is in neutral, the noise is slightly quieter. Again, this only happens when it's really cold out.

Any ideas?

Does the sound happen when your car is not moving?

Yes. Happens right as I start the car.

Also, the noise is either present, or entirely absent. When it gets cold enough outside, it appears. Otherwise, there's no such noise at all. Besides the noise, there is no perceivable different in my driving experience.

Since it's cold do you have your defroster blowing? If so, maybe it's your AC pulley bearing going out, or the alternator bearing. There's extra load on those two when it's cold and the defroster is going. Check the tensioner too.

You may want to remove the belt and spin each pulley to get a feel if one is rough. Another method would be to spray water or belt dressing on one pulley at a time when you have the noise to see if the noise goes away when spraying one pulley.

Thanks for the replies!

I'll try this when it's cold again. Can I use lithium grease instead? I don't currently have any "belt dressing".

A spray bottle with water is all you need.

Here are some videos to watch on how to figure out a squealing belt.

Don't use grease - it'll take forever to clean the pulleys & it'll destroy the belt. Use water. All you're looking for is the sound to change & that will tell you the sound is coming from the belt itself. Try to spray only one belt at a time.

Even if the belt looks good, it can get hard & slippery from age & heat.