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Registered User
Join Date: Aug 2013
Location: Dripping Springs TX
Posts: 9
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Help! Cam belt shaving on WP pulley
Rebuilt a 16v engine, new water pump and tensioner/roller pulleys, 8000 mile belt. The belt is shaving the front edge on the water pump pulley flange. It is not hitting anywhere else, including the flange on the tensioner pulley. Can't see/measure anything different on the water pump. It's the right tensioner pulley. Any ideas? I have nothing. Thanks!
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08-27-2013, 10:58 AM
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Registered
Join Date: Jan 2007
Posts: 2,370
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I wonder if the Water pump pulley was not pressed on the correct depth from the factory.
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08-27-2013, 12:21 PM
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Registered User
Join Date: May 2012
Posts: 383
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You may have turned the tensioner pulley in the wrong direction. That (lower) eccentric pulley is supposed to cam clockwise, IIRC, and you may have cammed it counterclockwise. That would "raise" the belt into the water pump pulley.
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08-27-2013, 01:14 PM
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Frankly my dear....
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^^ Are you perhaps thinking about the balance belt here? If you cam that incorrectly then it does push up and can touch the water pump, but I got the feeling that it was the timing belt DSDoug was talking about - might be wrong though..? As this is the 16V it will have the spring adjustable tensioner, that is impossible to cam incorrectly due to the inherent spring tension.
If the front of the timing belt is shaving on the water pump pulley I think zedsn might have a valid point - manufacturing fault?  Question is - how badly damaged is the belt becoming? Got any photos??
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Porsche - accept no substitute Blue 1999 Boxster - Brief encounter! Black 1988 944S - Ongoing project Black 1987 944S - Gone but not forgotten Metallic Black 1980 924 - Those were the days.... Red 1979 924 - Hmm Minerva blue 1979 924 - Where it all began! |
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08-27-2013, 01:58 PM
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Registered User
Join Date: May 2012
Posts: 383
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Yes, I am referring to the balance shaft belt. When he said "front edge on the water pump pulley flange" I assumed it was the balance shaft belt, which travels in front of the water pump pulley. He didn't say what kind of 16V it is, so I didn't make an assumption about the tensioner being a spring or hydraulic affair, but regardless of the tensioner type, the timing belt doesn't travel in front of the pulley flange, if that's what he actually meant.
I also don't know that the pulley can be pushed on too far, I would imagine it would be pushed on too little if anything, which would again interfere with the balance shaft belt, not the timing belt. |
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08-27-2013, 04:24 PM
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Registered User
Join Date: Aug 2013
Location: Dripping Springs TX
Posts: 9
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The car is an 87 so it does have the spring tensioner for the cam belt. The cam belt is the one shaving on the flange of the water pump, on the 'back side' of the flange.
In 360 miles, the pulley has shaved about .020" off of the width. I have two old water pumps on the bench and as far as I can tell, the gap between the pulley and the pump body is the same on all 3. The space from the body to the pulley flange is also the same. Could it be possible that during our very hot summer, while we rebuilt the motor, the belt, sitting on a shelf, took a 'set' and is now somehow warped. A simple (chuckle here) belt changeout may solve the problem but I hate to do that and still be shaving rubber. Thanks for the help! |
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08-28-2013, 06:25 AM
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Frankly my dear....
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Could be a combination of a slightly oversize cam belt and a thinner than usual water pump gasket..? I would drive it for a bit longer and assess whether it is going to take any more off - if not, it is probably going to be OK...
__________________
Porsche - accept no substitute Blue 1999 Boxster - Brief encounter! Black 1988 944S - Ongoing project Black 1987 944S - Gone but not forgotten Metallic Black 1980 924 - Those were the days.... Red 1979 924 - Hmm Minerva blue 1979 924 - Where it all began! |
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08-28-2013, 06:37 AM
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Registered User
Join Date: May 2012
Posts: 383
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New rollers, eh - are they on correctly, e.g. is the balance belt running with the balance belt rollers, and the cam belt running with the cam belt rollers? Normally the problem, if they were reversed, would be to allow the cam belt to slide too far back, as in the link below, but I'm wondering if you have the correct rollers in there - can you compare old to new?
The Rubber Band Broke - The "Early Edition 944" ©1999 by FR Wilk |
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08-28-2013, 10:19 AM
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Registered User
Join Date: Aug 2013
Location: Dripping Springs TX
Posts: 9
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This car has the spring tensioner and the proper roller is installed on it. It seems that the rate of shaving is reducing. I made a tool to easily keep track of the wearof the belt, through the window in the distributor back plate. My best guess is the belt took a set over the summer and is now 'bedding back in'. A new belt may be the answer. I'll post when the solution is certain.
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08-30-2013, 12:04 PM
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