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Subject Defective Timing Belt Tensioner?
     
Posted by flashstar on May 21, 2015 at 1:57 AM
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Message I'm scratching my head on this one. I'm using a 120k timing kit from Z1 with new oem auto tensioner.

I installed the timing belt on my Z tonight and ensured that the auto tensioner gap was set to 4mm. I then lightly pressed the tensioner (to keep the belt from slipping), tightened the bolts down, and rotated the engine back and forth 120 degrees. I followed the FSM and bolted the tensioner down while pressing it with around 17 ft lbs of force. Still 4mm. I then waited 5 minutes and checked the gap again. Again, 4mm.

Thinking I was in the clear, I rotated the engine clockwise 720 degrees and didn't notice anything unusual with the tensioner. To be sure, I rotated another 4 times but to my horror, the tensioner gap had grown to 10mm! The belt had become incredibly tight as well. It seems that the tensioner is expanding far too much. What else could be amiss?

I loosened the tensioner bolts to relieve stress on the belt and rotated CCW back to the original position (Piston 1 at TDC). The marks on the timing belt are still aligned with all 5 cam and crank gear marks.

What on earth do I do now? I'm guessing I'll need a large clamp to retract the tensioner (especially to take the remaining pressure off the belt). Should I start over or try another new tensioner? Do you think mine is defective? Am I making a rookie mistake?

Note: This is the second time I'm setting the tension. I tried setting the tension before but had overtightened the belt by mistake. I had placed a bit too much pressure on the tensioner while setting it originally, causing the tensioner gap to close to 3.2mm.

Thanks

     
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