Pulley bearing noise, slower than RPM

[-Nemesis-]

Just thought I'd throw this one out there to see what people know.

For the last few months when I start my engine there's a fairly typical pulley bearing squeel, it's not very loud. I've tracked it down to the back of the supercharger.

The thing is though, its squeeling noise is in relation to the engine revs, but it's no where near as fast as the engine revs. As in at idle, say 800rpm, it squeels probably 3 or 4 times a second. As you rev it, the frequency of it pics up. But it maintains that relation to the engines, much slower.

Just wondering why a bearing, if on its way out, would may a slow sounding squeek only every few revs, not each one? If that makes sense.... While the pulley connecting it to the crank is probably 1/3 the size of the harmonic balancer, so it should be 3 times as fast if anything....

Also, it goes away after 5-10 min when warm

[SIMMO84]

This will be hard to explain but................. could it be a gasket that is not clamped properely (imagine a turbo flange gasket or a gum leaf between your fingers) that would make that sort of sound. As th eengine warmes up the parts expand and tighten up on the gasket. Just an idea.

[1TUFFGQ]

What sort of supercharger is it. Can you put up a pic of the engine bay so I can see what sort of charger it is.
When you first start it up and the squealing starts, get a long shafted screw driver and put the blade end where you think the noise is coming from and the handle against your ear. Then move the blade around until you can isolate where the noise is loudest. I did that for a noisy bearing/idler pulley. Wasn't sure if it was the aircon pump or the pulley.