My serpentine belt keeps sliding forward on my fan clutch any guesses why cause I can't figure it out.

 

Year model and engine please

 

Could have a bad idler pulley, or another bad pulley, or the belt isn't tight enough. Check all pulley bearings for play.

I also would recommend getting the Gatorback belt as it has a much grippier surface

 

Sorry I didn't say in the first place it's a 96 4.0

 

Harmonic balancer

 

fixed my problem. Belt kept slipping off. Replaced it and haven't had a problem since.

 

Here's what one looks like:

 

My balancer is in good condition bit it may have a bit of a wobble

 

I replaced my harmonic balancer too, but I found that if the belt isn't tight enough, it'll still fall off.

Learned the hard way when I was going 90 on a 5 mile bridge and ended up getting towed home and cleaning my whole engine compartment off from coolant and tranny fluid.

 

I learned a similar lesson at 3 a.m. in a church parking lot in a snow storm