New to the whole EFI/serp belt thing. 87 f150 4x4 300 thrown the serp a couple of times, assuming something's out of alignment or the torsioner's shot. What to look for, how big a job (seems pretty simple) pull a new torsioner out of a junkyard or what? Thank. Matt.

 

Is your tensioner pulley steel with no flanges or plastic with flanges? If its steel, look to see if the belt isn't riding off the back (toward the engine/back of truck) of the pulley just a little bit. If thats the case, it may be your tensioner. The plastic flanged pulley is a little better in this case in that it won't allow the belt to hang off the edge of the pulley, but it will still be out of the plane of the rest of the pulleys and put stress on the belt.

My truck was doing the same thing as yours recently. When I had my belt off, I could move the tensioner pulley back and forth a little bit but enough to let the pulley sit at a angle. The new one from advance has no front to back motion at all. One from a junkyard that feels solid front to back should be fine, too. I can't say that that's cured my problems with belts as I only put the new part on two days ago, but so far, so good.

As far as doing it, it shouldn't take any more than ten or fifteen minutes. Just pull the belt off (if it hasn't fallen off first!), unbolt the pulley (if you're reusing it), and then other bolt that the tensioner 'pivots' on. The tensioner will come off (don't worry about a spring or anything jumping at you, its contained) and the new one bolts on. Easy peasy lemon squeezy.

 

Thanks for the info, I'll check it out.