Join the Car Talk Community!

I have a question my mechanic can't seem to answer...

RSS
Dear Tom and Ray:


I have a question my mechanic can't seem to answer. In the right front of the engine compartment of my '85 V8 Thunderbird, the belt that turns the alternator and air pump makes an annoying whistling-whining noise. When water is poured on the belt at idle speed, the sound is cut in half, which seems to indicate that it IS the belt. It's one of those multi-groove belts. I had a new one put on and it's making the same sound. What could be the cause?
Hank

TOM: Belts can make noise if they're too loose, too tight, or misaligned. And if a new belt didn't fix it, Hank, my guess is that it's probably a misaligned belt tensioner pulley. The pulley on the tensioner isn't quite in line with the others, and what you're hearing is the rubber belt rubbing against the side of that steel pulley.

RAY: When you pour water on it, the water is acting as a lubricant, and is allowing the rubber to slide along the steel more easily, kind of like how your shoe slides along the sidewalk more easily after you step in...uh...wet leaves. And that's what makes the noise subside.

TOM: So you have two choices, Hank. You can replace the belt tensioner pulley assembly and the idler support bracket. Your Ford dealer should have a Technical Service Bulletin on this problem, and can tell you or your mechanic exactly which parts are needed.

RAY: Or, you can change your taste in music and go for something that will drown out this belt noise. Try something like heavy metal.
Tags (Browse All)

You must be logged in to leave a comment. Login / Signup
Support for Car Talk is provided by:

Donate Your Car,
Support Your NPR Station

...and get a tax break!

Get Started

Find a Mechanic


Go



Submit


Rocket Fuel