i need to change the serpentine belt on a 1988 f150...i did it once upon a time, but i've forgotten the trick to release the tensioner.
can anyone provide an explanation of how to do it?
dave f

 

I can't tell you what the size of the wrench you need off the top of my head, but just play around and find the right size, put it on, pull the tensioner up and then you're good.

 

its the 3/8 inch wrench i beleive, im changing mine tomorrow

 

If you are talking about the serpentine belt tensioner, I'd go ahead and get a serpentine belt tensioner tool from your local autoparts store which is less than $15. Use that to do it safely and the easy way.
You turn that tool in the opposite direction where the belt tensioner is applying tension.

 

theres a special tool for it but im thinking that when i did mine on my 351 in my old F 250 that i used a breaker bar with a socket on the bolt on the tensioner pulley it to push it or pull it to get the belt loose

 

All of 'em I've done so far have had a square hole in the tensioner arm that just fits a breaker bar. I usually use my ratchet, cause that means one less tool to cart back and forth to the garage.