Hey guys i a 1998 4.0 ohv and there seems to be a kind of rotational bearing noise coming from the front of my motor. It kind of sounds like there is a bearing that is wearing out. Now it only seems to be at idle, whenever I rev it up, the noise goes away.
there is about 160,000 km, or about 100,000 mile on the odo if that helps.
thanks

 

More than likely it's the tension pulley. Usually if the water pump bearing was going bad it would start to leak.

 

Check the idler pulley, & tensioner pulley, then if these are ok, then reolace the serpentine belt, just did mine and before I did, it sounded like a bearing, Turned out it was the belt making the noise.
Jim

 

UPDATE

It was the tensioner pulley, thank god nice an easy