I have had this problem in the past. When I rev the car up to about 7000 rpm I always loose the belt. I had a 4 rib belt on there for a while and it actually stayed on for a few months. But now3 I keep losing them again. I know it could be cause by a loose underdrive pulley but can it also be a bad tensioner? I have never changed the tensioner on ym car so I was thinking it may be the cause. Is there any way to test the tensioner to see if it is good? I am assuming it shouldnt wiggle or anything correct?

Dave
05 Ford F150 SuperCrew FX4

bypas the tensioner by getting a 40" belt (i THINK thats the right length, you might have to try a few out in that range though) belt from your parts store. loosen the bolts holding the p/s pump and reliese the tension on the current belt and remove it. loosen the tensioner to get it out of the way, and wrap the new belt around the crankshaft pully and the p/s pully ONLY. then using your wieght (or a friend), pull the power steering pump back into place to add tension to the belt and re-tighten the bolts. make sure that the tensioner is not on the belt at all. if it still falls of, its the crankshaft pully. if it stays on, its the tensioner (in most instances).

oh, just remembered that you have an UDP..in that case you might want to try somthing like a 38" belt.

quite a while ago, someone posted a link to a tensioner bearing rebuild kit that was <20 bucks. youll have to search around a bit for it though i belive. it sure beats pay the 100+ satan wants for a new tensioner. (note* ive never tried the rebuild kit, but ive heard that others had great results).

i believe theres a section in the "things weve seen before" forum that should have more info on this fairly common problem.

best of luck.


edit: forgot to add that wiggling the tensioner around to tell if it is bad or not really doesnt tell you for sure. mine came brand new with a little bit of wiggle to it, and minute differences in the wobbling that are unnoticable to the hand might be causing the problem. that's why i suggested the above method for testing it out.

:shhh: i do cocaine :/shhh: