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Old 11-01-2017, 08:07 AM   #1
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Squeaky Belt

Hello all!!

The box has been running well for the past months, so nothing to report on...until now that is. We have a squeaking serpentine belt issue and need some info on the crank pulley.

We are on our 2nd new belt and it has now started to squeak again. The first one was about a year old (5000 miles) and it would squeak on cold days and we are now getting to cold days again. Once warmed up enough the squeak goes away. We replaced it 4 weeks ago with a new belt because it was easy to do. We are 1000% certain it's the belt. Allie replaced the tensioner bearing when she changed the belt but I don't think it needed it. If you give the toothed side of the belt a real quick squirt of carb cleaner it goes quiet for a bit.

The only thing I can think of to mention is the crank pulley has a bit of a wobble in it, like someone pried it from behind to take it off and bent it slightly. I'm now thinking that this slight wobble, when the belt is cold is causing the noise. Anyone see or have this happen before?? Is it safe to assume that the crank pulley should run true??

1966 912, 1976 911
1986 944, 2000 Boxster
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Old 11-01-2017, 09:17 AM   #2
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Apparently it is never safe to assume anything. In case you missed it.


Edit; I find myself wishing they had used a good harmonic balancer like the Fluidampr I have in my garage. Could have gotten rid of that massive DMF.

Last edited by 911monty; 11-01-2017 at 09:47 AM.
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Old 11-01-2017, 09:39 AM   #3
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Hi John, I've recently dealt with a wobbling crankshaft serpentine belt pulley in my 2001 2.7, and was surprised to find very little elsewhere documented about this problem:

I replaced the old (bent) pulley with the newer (straight) one, and while this managed to correct the serpentine belt vibration and runout, inspecting the pulleys more closely on a surface plate revealed troubling observations they they might have not been very well balanced when originally manufactured. The newer replacement pulley I stumbled across put on had thicker dimensions, so it gives me some hope of lasting longer.

Nice job onserving your serpentine belt also has runout. I suspect this "bent crank pulley" problem may be a whole lot more common than most people here realize!
2001 Boxster
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Old 11-02-2017, 05:42 AM   #4
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Apply beeswax, had a original Toyota Tundra belt that squeaked and lasted over 200000 mi. The wax stopped the squeak.
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Old 11-02-2017, 06:15 AM   #5
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I replaced my belt at 60,000 miles and it had a slight squeak until warm as well. The old belt didn't make a sound and looked ok when I removed it.

I sprayed on some 'belt dressing' I got at Canadian Tire and it stopped the squeaking. The Box is in hibernation now but we'll see (hear) if it squeaks next spring. I'm counting the days . . . .

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