Serpentine Belt Issue

[BABDBAT]

I have a 1996 Mustang with a 4.6 DOHC motor. I had to rebuilt approx 1K miles ago. I recently had a noise from the Serpentine Belt and as I went to change it I noticed the belt was not on the Harmonic Damper pulley correctly, it was 2 groves toward the block. I reset the belt to the proper position and when I started the motor it immediately jumped back to where it had been running. I then replaced the belt thinking the belt was damaged. When I started it again with the new Motorcraft belt did the same thing. At first I thought may by the damper pulley was not fully seated or torque properly, but it doesn’t appear that is it, I checked the Harmonic Damper and the bolt was tight (116 ftlbs). I have looked at both the A/C Compressor and P/S Pump and they are both tight to the front of the motor. Anyone have any ideas I am considering ordering a new damper/pulley and replacing it along with a new key and ARP Bolt. This motor was rebuilt due to a spun rod bearing and I also wonder if they did something with the crank to cause this problem. TIA

 

[lwarrior1016]

What kind of water pump pulley is on it? You should be able to use a ruler across the pullies and determine which one is out of line. Can you get a couple pictures of the belt on the engine. We might be able to spot the misalignment.

 

[96blak54]

The dampener rubber could be getting weak. Rubber and age dont mix

 

[Werecow]

I saw on a 4.0 V6 the dampener had slipped and was causing the belt to keep kicking back. The rubber was worn out on it and it had slipped forward causing the belt to keep kicking backwards.. it was on an episode of south main auto repair in YouTube, can't remember the exact ep, but it may explain it better than I can. It dies sound just like what you're describing tho...