reasons for walking timing belt?

[91gsx]

recently did my timing belt. all timing marks are lined up. the thing is that the belt walks towards the valve cover about 1/4" so that the "whole" belt isn't on the cam gears. anyone have any knowledge of why this would happen?

 

[steve]

Mine was also walking to the inside and wearing that edge down.
The only reasons I could think of was that either one of the pulleys wasn't parallel anymore or the tension was uneven across the belt.
I replaced the front cover to eliminate the chance that the oil pump sprocket was somehow out of line but as I looked closer I noticed that the tensioner arm had worn out the pivot on the front motor mount causing the tensioner pulley to be slightly angled against the belt. replacing the front mount and tensioner arm fixed the problem.

Steve

 

[91gsx]

hmm thanks i will have to check that out. appreciate the reply

 

[willza]

after rebuild of my engine i noticed after i put on the timing belt and starting it that the belt moved out and cut away the timing belt cover... after inspection.. found that the tension pulley came loose and was angled down causeing the belt movment.. might be impractical but could happen.. first go with Steve's thoughts first. then check pullys. hope it help peace.