Originally Posted by JohnKoaWood

2 most common issues I have found on the number of cars I have been working on...

1) over tightening the jam nuts... they only need to be snug, not squeak tight...
2) over tightening the mounting hardware... if the mounting bolts are too tight, the ends will distort when you adjust the tensioner... causing them to break... (have seen a few looking like the pictures you posted... each one had the moutning bolts WAY too tight, and MOST also had the jam nuts WAY too tight)

next time, loosen the mount bolts before you adjust the adjuster... then snug them once the belt is tensioned.

Originally Posted by Adonay

Thank you for the tip its not obvious but i have actually tried that as well . This time the tentioner broke becouse a bolt had backed out and the tentioner hit the road. Funny thing is that the threads in the block mount are worn out .