I just changed my timing belt and tensioner, balance shaft belt and tensioner, and water pump. Once I got the motor mount back on I started the engine briefly and everything looked good. So I proceeded to install the timing belt cover and the rest of it. Once done I started the car again and let it run long enough to come up to normal operating temperature. I didn't notice any strange noises or anything, but once I shut it off and looked more at it, I found that the timing belt must be trying to walk off of the pulley(s). It wore right through the upper timing cover, on the side closest to the firewall.

After work tonight I will start pulling the timing cover back off. What could I be missing? I didn't see anything in the FAQ specifically about this.

 

I would think somehow the upper TB cover is misaligned. Hard to believe the camshaft sprocket has moved. Did you remove camshaft sprocket?

good luck

 

what's the risk in running engine with the TB cover having a small hole?

 

I did not remove the cam sprocket. After work I pulled it back apart and see a lot of rubbing on the inside of the lower timing cover as well, I can't see what is causing or allowing the belt to walk

 

Check your crankshaft and camshaft end play.

I discovered a hole in lower TB cover on a 90EX when changing TB. I suspected the crankshaft was wandering in/out enough to allow the crankshaft pulley edge to contact cover.

However, I never inspected the upper camshaft and sprocket for play since I didn't have your problem.

I repaired my lower TB cover w/ nylon ripstop from an umbrella and epoxy adhesive, w/ black spray paint to match. The damage did not occur again while I owned.

good luck

 

Another thing is the order and orientation of the big guide-washer alongside the crankshaft sprocket. That's supposed to prevent the belt from walking off the sprockets inwards. The larger sprocket for the balance-shaft belt prevents it from walking off outwards.

What about any of the other pulleys? Tensioner pulley bracket might be bent, so the pulley might not be perfectly square, also allowing the belt to walk off.

 

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