I had both serpitine belts replaced on my 350 Z. Since then, they make noise. I have taken it back several times for adjustments. It still makes noise when first started and then stops after a bit. It seems worse when very cold or raining. What cab I do to make it stop?
Pick up a can of belt conditioner at your local auto parts store and spray it on there as per the instructions. Should quiet it up. It’s likely that if you’ve got a new belt squealing that the pulleys are a bit dirty, and the belt is slipping slightly. The conditioner should keep the noise at bay for a while, and it’s cheaper than having someone remove both belts and clean it the hard way.
“Serpitine (Serpentine) Belts” 101:
Cars sometimes drive engine accessories with V-belts, which have a “V” cross-section profile and drive accessories from the narrower side of the belt. Sometimes they employ serpentine belts instead or additionally.
A serpent is a “noxious creature that creeps, hisses, or stings.” However, a serpentine belt is named for one type of serpent in particular, a snake. A serpentine belt gets its name from the way it “snakes” around accessory pulleys, weaving in and around and even driving some pulleys (often water pumps) not from its ribbed side, but from the smooth back side, as well.
Anything I’ve ever read on belt dressing sprays does not recommend its use for ribbed serpentine belts, but rather is intended for V-belts.
New belts are squeaky clean and fresh. I’d give them a chance to break-in and get a little dusty and dirty before I’d worry too much, provided the tension is set correctly (as specified by car manufacturer).
Should the problem not go away in time, I’d check to be sure pulleys / bearings aren’t worn out or dragging and I’d use a straight-edge to check pulley alignment.
I can’t recommend spraying them with chemicals.