Yeah its whistling alright. My brother just bought his cherokee as well. Its a 2000 with 160K on it and its bone stock. When he fires it up, after it warms up it starts to whistle, and I mean you can here this think like a back up beeper. I hear him coming up the driveway before I see him. It has no effect on power, performance or anything. It just makes a high pitch whistle. From what I can gain its coming from the intake area, and maybe underneath the intake. Sprayed some either around and no idle change, so vacume is ruled out. I have pulled and moved and shook and pinched and all sorts of things to the things in the general area but have got no response. It has gotten worse and now does it all the time when he is driving, but used to come on speraticly and then go away. It never had this problem when he bought it. I am at a loss. anyone know what this could be? Thanks!!

 

Pull out the REALLY long screwdriver and start listening around...
Check the water pump or idler pulley, I got my money on one of those two......

 

A bearing going out then? sounds like a great idea! Time for the home made stethoscope.

 

check the belt and pulleys also check for slack in the belf make sure its pretty tight

1 foot of belt = 1/2 inch of movement

 

I agree with the other guys. Your whistling is probably actually a high pitched squeal coming from a dying bearing somewhere in the pulley system.

 

my money is on it being a turbo

 

I seen a build thread on a board of someone who put one on a 4.0...
I'll sees if I can findey...

 

peterson's 4wheel&offroad put an eaton blower on a cherokee.

 

lol... "Yeah I'm running a 4.7 stroker w/ an Eaton and spray... It goes like someone lit its [donkey] on fire...I just can't figure out why I keep snapping axles and U's..."

 

Sounds like were going astray here, He tells me its coming from the back of the motor. He is mechanically inclined, and has done plenty of wrenching.

 

Automatic or Manual?

 

if its manual throw out bearing sounds like a mouse

 

I was thinking throw-out or pilot bearings...

 

Its an automatic.

 

Some one weld in a whistle tip?