My 4runner never squealed at all. one day i went offroading and it came bcak squealing. everytime i started it it would squeal for 30 seconds or until i reved it up. i replaced the alt belt and checked to make sure the alt bearings were spinning freely and all seemed fine. things were quiet until next time i went offroading and now it squeals the same it did before. could the belt be slipping off the pulley until it warms up a few seconds later? im pretty sure i tightened it as neccesary. i have replaced all sorts of belts on vehicles and never had this kind of trouble. any info would be greatly appreciated

 

Sounds like it to me. Try to tighten it a little more when it's warm.Mike

 

A new belt can stretch after you first install it. I find I need to snug up the belts, especially the alternator belt 2-3 times after installing a new belt before it settles in. You might also check all the pulleys on the belt see if any have any oil/grease/dirt on them.

 

would WD-40 on the pulleys cause them to slip everytime? is it possible for dirt to get embedded in the belts causing them to squeal when cold?

 

WD-40 is oil, oil is slippery and makes things slip. Rubber v-belts want to be clean and dry to work the best, they operate on friction. If the blets slip too much, the surface can become "glazed" and that can also cause squealing.