My XJ is squealing while driving. The serpentine belt is quite new so don’t think it’s that. What other belts does an 89 manual XJ have? Trying to figure out best place to start troubleshooting.

 

Check the damper on the end of the crankshaft. they are prone to slip and misalign the belt causing squealing.

 

Could be a pulley too. Listen around using a hose as a stethoscope. Don't get it in the fan.

 

Was it squealing before you changed the belt? Did it squeal when you first installed the new belt? How long afterwards did it start squealing? How did you measure the belt tension?

New belts stretch quite a bit with initial use. New belt should be 180-200#. Used is 140-160#. Used is more than 15 minutes of running. So check your belt tension in addition to the other suggestions above.

 

Get a Krikit II belt tension gauge instead of guessing based inaccurate methods like twisting the belt. Too loose and it slips and squeals, too tight you kill bearings. The local auto store probably has a loaner one if you don't want to spend the $20.

 

I used to swear by dayco belts, while I've had great luck with them on my XJ 4.0s when I put one on my jk 3.8 it was hell. New everything with exception to the AC pulley which got multiple cleaning sessions to no avail. I switched up to a continental belt which had a textured feel to the flat surface and that took care of the issue completely.

also for the record. Your jeep xj 4.0 or 2.5 only have 1 belt. Manual or auto makes no difference to the serpentine belt setup.

 

I would get the tool. I was surprised when I did. Compared to other vehicles I’ve had, the belt tension spec feels crazy tight on the vehicle. So it’s possible it’s not tight enough. But too tight and you’ll spend more than the $20 tool destroying accessory bearings.