3.4 timing belt issues

[JDz34]

I purchaced a 92 z34 lumina a few months back. The previous owner had replaced the engine and installed all new timing components. After I had driven the car a couple of weeks I noticed a noise comming from the timing belt area. I removed covers to find that the new belt had pushed forward and chewed off half the belt. Upon teardown I found that the front snout of the intermediate shaft was broken and only held together by the bolt. I removed engine and replaced shaft. All pulleys and tesioner pulley appeared new and therefore reusable. I installed a new belt and have been driving for a couple of weeks when I heard the same noise from the belt area. I removed covers to find the same chewed up belt. With the engine running with the covers off everything looks ok. I can push the belt to the center of pulleys with a screwdriver and it running and as soon as I remove pressue it runs right back to the outside edge of pulleys. any ideas would be appreciated Jeremy

[Schurkey]

Pulley alignment issue?

I had that happen once, Stealership installs timing belt; within 20K miles the 1/4" of the outside edge of the belt is gone. Replacing pulleys and belt fixed problem.

[JDz34]

Well I flipped both idler pulleys the other way and put a different tensioner bracket and tensioner. I put a straight edge as best I could on the pulleys and near as I could tell were all ok. I put it back together and I guess will see if it chews up the belt again. I guess if it does it again I'll have to pull the engine and try to mic all the shafts and pulleys to see which one is off time will tell I guess.

[Smittro]

As a general rule of thumb on the LQ1 it's a good idea to replace the plastic pullies everytime a new timming belt is installed..
From personal experiance it's worn pullies that usually cause belt walk.. It does'nt have to be much either..
May not even be able to see it with your eyes externally.. The sealed bearing races could be worn/damaged and effect "walk" as well..

Just my .02