Shredded serpentine belt

What would cause my serpentine belt to shred? The belt had about 1k on it and I have recently changed the ps pump and box. The ps pump is from a TJ and the pulleys looked identical in size and had amount of grooves. I don't think I over tighten it. what gives?

My belt did that when the harmonic balancer decided to start moving. Get a new belt and install it and see if the belt walks one set of grooves in the crankshaft pulley. If that happening then get it to the garage like today to get the harmonic balancer changed.

Mine harmonic balancer failed at 115,000 miles, how many miles on your XJ? The word on here is the harmonic balancer and the Crankshaft position sensor (CPS) both can fail at anytime over 100K miles.

My junk has about 180k on it. I got it with 120k on it. I have never changed the harmonic balancer on this rig. I have changed one on my other XJ which had 220k on it.

easy or hard job? How many clams it cost ya Martin?

Try this also: when the belt is off and everything is cold, (as in the engine and such) grab with both hand every pulley and try and "shake" it sideways. See if any one of them has play: I have seen a water pump going bad make the pulley wobble on it and end up shreding most of the belt.

I had mine changed 4 years ago by my local garage. I was getting ready to move to a new town and did not have time to fix the XJ and pack. I think I paid like 1.2 hours plus the cost of the part. I got out of there for $125 if I recall.

Eagle has posted how the Mopar damper has changed and more work is required to install it. He also said Crown Automotive still sells the OE style damper used on the Renix XJs. I am sure Eagle will fill in if i got it wrong.

I will tell you with the radiator removed you will have MUCH more room to work but that required draining the cooling system. If you are doing the work I'd consider killing many birds with one stone. Things you could change while doing this job are:

* Radiator
* Radiator hoses
* fan clutch for mechanical fan
* Fan belt
* Idle pulley by AC compressor

* Thermostat - use Mopar 195F comes with gasket and has RTV applied
* Bearing for mechanical fan - this is a dealer part and you have to buy the AC mounting bracket
* Water Pump - buy your gasket at the dealer, comes with RTV applied. Also with the water pump off it will be easy to change power steering hoses since you have to remove the power steering pump to change the water pump.

You can do all of these or just what your budget allows. I will tell you with the radiator removed you will have lots of room to install the crank shaft damper puller.

Also go to Napa and buy a Kriket II belt tensioner. I posted in the info in the past month or two. I used mine when installing my new fan belt and tightened it until i was in the 180-200 lb range. For a used belt on my 88 XJ the range is 140-160 lbs.

I recommend radiator hoses from the dealer, figure $18 to $20 for each hose. On fan belts use what you like but I have been using goodyear. It has cross cuts on the grooves to cut down on noise. I got mine 4 years ago at the neighborhood parts store, now i see Autozone sells them for $30 for my XJ.

I am the type who prefers to do do all the work in one area which I can so I am not removing the same parts just weeks or a few months later.

The last time I took out the radiator I installed an elbow where the drain cock is, added a short length of tubing/hose clamp, through a hole in my mud skirt, put a plug in/hose clamp and tied it down with a twist tie. Makes draining the raidator a snap and saves on anti-freeze, if you often get into major motor assemblies. Greased all the hardware, the last time I had it apart, makes taking it out a snap, don´t loose much coolant. Catch it in a clean bucket, poor it through a paint filter, use it again, earth friendly and cheap.

I started shreadding belts and I thought it was the new water pump I installed. So I got a spacer, but I tried to put it on it was actually the PS pump bracket that was out of alignment. Does your belt hang over the edge of the water pump pulley?