Aluminum pulley squeal
 

I have replaced the water pump pulley now a couple of times because of belt squealing when running the a/c. I have replaced the belts, which temporarily solves the problem, but the squealing returns after a few days.

I have tried different belt manufacturers, but they all do it. I have also tried belt dressing to no avail. It is only when running the a/c.

Does anyone else have this problem too. Is the only cure a steel pulley?

Your compressor is low on freon or you have a bearing going out on your compressor....or...your A/C is freezing up and making the pump work too hard.

Try cleaning the pulleys/belt with a brake clean . Lightly sand the aluminum pulley with scotch brite or fine sand paper. I had a alt belt squealing problem and alum waterpump pulley and I had to really tighten the belt to get it to stop. Another old trick is put a little copper coat on the belt as a dressing, it has a grit in it that helps. M2C

how is the alignment on the belts? Sometimes by going with a different pulley it off-sets the Alignment.