Last nigh while doing some Christmas shopping my Jeep Cherokee started making a horrible noise. I stopped to check it out and found that the idler pulley had spit out all it bearings and was just running on the races. Luckily, the belt stayed in place while I went to the local parts store and back to my shop.
The interesting thing about this failure was that there was no warning. On my off road jeep the idler pulley has been squeaking for years but has never failed. This one never made a sound before it catastrophically failed.
So, if you Jeep has a few miles on it you might want to consider changing out the idler pulley as preventive maintenance. I was lucky that the pulley did not cut the water line although it did make a nasty mark on it.
To help you out, I am offering a Holiday special on the idler pulley for the XJ. Order before the end of January and I will sell you one for $12 plus shipping to your location. Shipping to most places is $11. We can also combine shipping if you order others items and ship them for that same $11.
See http://induprod.com/Jeepparts2.shtml for more Jeep Parts information.