Timing belt tensioner bolt

[1000ninjas]

so i have a 2.5 N/A subaru impreza, maybe a year ago i had my timing belt tensioner collapse, so i replaced it with the timing belt, it lasted a solid year. then, i had the tensioner bolt loosen up and come out, it destroyed the threads, but some how the engine stayed in time, i re-threaded the hole and put helicoil in, after replacing it, i forgot to pull the pin on the tensioner, so i took it back apart re-torqued it and pulled the pin, not even a week later it did it again, i figured it was because i torqued it with the belt on and it caused the torque wrench to click when it wasn't actually at 29ftlbs, it lasted like 2 days like this and then it did it again, and again the car stayed in time, and so i replaced the tensioner and bolt again, and before i even got the bolt down to torque it stripped out and pulled the helicoil out with it, i checked the threads and they seemed to be good, so i replaced the helicoil and put high strength lock-tight on it, i let that cure for 24hrs, and then i got a stronger bolt from home depot, i also put high strength lock-tight on it, i put the tensioner on and at torque and let the lock-tight cure for 48hrs, then put the belt on and it lasted a week again, i don't understand why the bolt keeps backing out, i'm losing my mind, it seems like nobody else has had this issue.

 

[bmart]

Check your torque wrench calibration and that you aren't mixing ft-lbs and NM. I've done a bunch of them and never had one come loose.

 

[mjm4jc]

That is a mystery for sure. Will require some brainstorming. But that bolt should never come loose or come out. Are you sure that you're bolt isn't a hair too long, so that you are actually torqueing against the bottomed-out housing and not the pulley itself? If so, this will leave the pulley slightly loose, and over time the loose pulley will cause that bolt to come out.