Kris Hansen

I do not see how overtorquing these rollers would hurt them. Both are designated with somewhat high torque anyway.

Catware

No, I didn't hear any noises leading up to this. I do try to stay well on top of maintenance issues with this car. It does idle rough, which I thought was related to a throttle body needing cleaning. The supercharger & its software tends to amplify issues such as that. The SC is also due for a rebuild and rattles a bit.

The pulleys were not crooked after loosing their bearings -- they were actually straight, it's just the bearings for both were found directly below after taking the covers off.

The idler pulley (on the driver's side) was actually partly fused to its inner hub -- probably from heating up. The tensioner pulley still rotated, but this was probably second to go. The timing belt itself looked great, surprisingly.

The bolts were overtightened, as I had a lot of problem getting each of them out and greatly feared breaking one off in the block. But I did get them out okay. However, this would not affect pulley rotation since the bearing race is about an inch radius from the bolt -- i.e. the inner part does not rotate it just bolts to the block.

I'll try to take photos of the parts tonight.

Digit@lex

by overtightening. The inner sleeve where the bolt head makes contact with does not move.

Catware

When following the Blauparts tips for initial replacement of the camshaft seals, I realized they didn't included the right tool to pull the seals and their instructions said to drive a screw into the seal and pull it out. I did that, but scored the side of the camshaft which caused an oil leak.

I replaced the camshaft 2000 miles later and while doing so noticed the camchain tensioner was going bad so replaced that too.

Maybe I did something wrong with that job which greatly increased the force on the timing belt. The force would then transfer to the pulleys it ran over and caused them to heat up and break.

It's just very wierd that the bearings would blow out on both of these parts!

Kris Hansen

and I'd have guessed the waterpuump would have also started leaking..

Catware

...not enough to cause a problem with the timing belt but I'll replace the pump too. I do not think coolant was leaking but I will inspect it closer tonight.

I never heard any unusual noises from the front, other than the slight rattle from the rear of the supercharger where the bearings need replacing.

This chain of events is just very strange, especially considering that the timing belt did not melt through.

77'911

The problem here is that the bearings and housings are designed to take a specified torque, no more,no less. Deviate from the factory spec and you get the results that were discussed above. The bearings and casing is designed for a certain lifespan under a specified level or torque(pressure). The torque spec is especially critical when the bolt is threaded into an aluminum casing(ie different metals with varing properties(hard, soft, expansion & contraction rates). Sorry Kris, this is one where I strongly deviate from your opinion. This was a problem with 944's and 944 turbos that had numerous tensioner rollers.

ModifiedA4

i.e. if the inner hub is longer on one side vs the other then installing the bearing backwards would preload the bolt load through the bearing to the outer race.

one sign of this being true is if the bearing wouldnt spin easily once installed.

just a thought.

some other things that could cause this would be a conical/special washer being installed backwards as well.

Kris Hansen

will in no way impact the performance of the bearings. There is no way it could deform the 'hub', or the inner race. there is no way that too much torque would cause the pulley to interfere with anything. Granted, I toruqe everyting to spec, but in the case of the main idler, it's like 30+ lb/ft...

Kris Hansen

markings on the back of the belt?