Hey guys, I'm new here and I've been searching for a problem like mine but haven't found anything so hopefully one of you can help me out. I have a 1990 4runner v6. I keep having the timing belt slip. The first time I assumed it was just worn out parts so I replaced the belt, idler pully and tensioner (aftermarket autozone parts) back in February and it ran pretty good until about 3 weeks. Right when I turned it over the belt slipped. Tore it apart and replaced the belt with an oem belt and the next day it slipped again right when I turned it over, tore it apart put it back together ran for a week and slipped again today. Every time I have timed it to 99.9% perfect, also the crank gear has bean off two teeth from the cam gears everytime this has happened. I had the crank gear inspected to make sure it wasn't wore down and it was all cleared by a Toyota mechanic. My dad and I are stumped and don't have much direction right now. Maybe one of you have encountered something like this that could help me

 

Slipped? Are you sure? How could a toothed belt (under considerable tension) "slip"?

How do you know it slipped? (Take it apart, set crank to TDC, and each cam sprocket is cocked one tooth?) Are you sure it was installed correctly? (Put in the belt, turn the crank 2 or 4 revolutions, everything is lined up perfectly again?)

 

Is the woodruff key that holds the crank gear worn or missing? The cam gear dowels work or missing?

Are you getting the timing belt tensioner installed properly

Seems sometime back someone else had a similar problem. MudHippy, I believe, posted up the procedure on how to install the timing belt and tensioner to ensure the slack did not cause it to jump a tooth or two.

 

If the tensioner, idlers, and crank pulley all check out, I wonder if the cams are binding? Do they turn freely when you have the belt off (other than being restricted by the cam/spring interface of course)?