noise from the engine compartment

[ericz]

I have a 99 XJ, automatic. A noise has developed. It does not appear to be from the belt but rather from the rear passenger side of the engine compartment.(although I could be mistaken)
It usually works itself out after a few minutes - before I can track it down.
The noise is difficult to describe, it is similar to a belt squeeking but deeper in tone. Almost like something rubbing.

it happens with the air conditioning off and on.

Thats all the info I can think of at the moment.
Any thoughts?
Thanks
EricZ

[AZ Jeff]

Does it change with engine speed?

One way to rule out belt noise--pour water on the belt while it's running. Water will actually quiet down the belt for a couple of minutes, and then, as it dries, return.

[GSequoia]

How's the harmonic balancer look? It's possible that it's starting to go, making the pully slip and the belt and/or pully is hitting the engine.

[ericz]

The noise started at idle them went away until I reved the engine and it came back for a minute while I was driving then went away.

It has been quite for a day now.

Well see...

[rroalf]

mines doing the same thing. i replaced the belt, this weekend im replacing the waterpump and thermostats as well as flushing hte system i will let you know it the water pump fixes it unless anyone else has any ideas. im gonna chekc hte rest of the pulleys we'll i got the belt off.

[falierpze]

mine is also doing the same thing squeaky sound on the right side of the engine compartment when aircon is engaging, my mechanic told me that it could be coming from the aircon clutch i dont know how to test this before spending much on replacing the clutch