So I've got a 86 GL-10 4wd Turbo Wagon. A while back I was headed home from work and and the car just died. No noise what so ever. I just died. I got it home and checked some things out and I ended up pulling the timing covers off. The passenger side belt was just fine, but the every tooth on the drivers side belt had been chewed off. Both cams roll just fine as well as the crank. I rebuilt the motor from the heads up in may of 2016 so everything is fresh. I put a new Dayco timing kit on when rebuilding it so there shouldn't be any problems. It's an easy fix I just want to make sure I'm not missing anything. Any ideas on what could have happened?

There is a toothed pulley on the left side, that the left timing belt teeth turns.  They need replacing every 60,000 to 100,000 miles.  It could have seized up.  The oil pump also has teethed gears that the left timing belt teeth turns.  It could also have seized up.

when you take it apart you'll find a seized pulley or need to diagnose something else. 

Belt tensioner failed? Fell off? Not set? I've also had the rear belt guide fall off the oil pump pulley...

Edited February 16, 20179 yr by Len Dawg

What the others wrote. Replace the 3 idlers / bearings when you change the belts. They usually are good for about as long as the belt, but not 2 belts.

 

Use only top quality idlers and belts, not cheap ones.

Check the oil pump rotates.

 

You might want to reseal it while you are in there.   If there is any leak at all, go for it.  You may find the oil pump shaft is chewed up.    I suspect this caused one of my timing belt failures.

Possibly could also be defective timing belt.  Had a belt on my '87 gl for years and swapped it out at the appointed time.  The new one was chewed to shreds within 3,000 mi.  Replaced that without any major rebuilding and it went for another 50,000 plus... If all the components seem OK, belts are cheap and since it is a non interference motor,to me, would be worth trying new belts vs a major re-do. Especially since you are a diy. Takes me about 4 hrs to do belts these days.  Good luck.