Viperbob1

So something I have yet to see or even hear about. I have a Gen2 997 S in the shop with about 110K miles which has a factory dampened vibration dampener on the crankshaft. Car was making bad noise. Turn out the our metal part of the dampener (the part where they drill to balance assembly) and the sandwiched rubber piece just came of the inner dampener. There are no marks, partial release, or anything. It appears the inner piece just lost any adhesion and came off. I thought I had pic but will post Monday when I get back to shop.

DC911S

Thats one mod I never do, change the harmonic balancer to a lighter one. Lots of dummies get aftermarket ones on Fords and Chevys and destroy their engines. I've not heard of a OEM Porsche one failing though. This will be interesting to follow.

Bruce In Philly

I don't understand.... is this a mod or something that is standard? My car is 118K miles.... so what kind of noise? A vibration?

Peace
Bruce in Philly

Viperbob1

Factory harmonic balancer. The car was making a tink tink tink noise. I will post some pics tomorrow.

Petza914

While be belt is off to replace the balancer, check all of the pulleys not only by spinning them but also for proper alignment. If something like the alternator, A/C compressor, or water pump pulley has moved or loosened, it could be putting a lateral stress on the other pulleys as the belt tries to run crooked while under tension.

I've only seen this failure once before and also a tensioner pulley failure where that pulley came apart once before.

Viperbob1

Here is the balancer as it should be in first pic. And how it came off. When it disengages inner and outer ring the outer part cant just come off and spin into engine compartment or fall out the bottom. The motor mount behind keeps it sort of in place. The inner spins around inside the outer piece now and it can wobble and make contact on the engine mount (the tink tink we were hearing). Just and FYI for cars getting older with more miles. We did not have any sort of belt or component failure so it just failed.

Iceter

This is a common failure on classic cars, but not one I've seen on a modern car. I guess any time there are two pieces of metal bonded together with rubber, there can be a failure. It's fortunate that the balancing ring didn't come off entirely. It's heavy and at speed, it can do some real damage to the crank and to nearby components when it disengages from the balancer pulley.

I would think that if your ring shifted, you would have had a noticeable vibration at certain RPMs. As the ring shifts from its original, balanced, position, the crank will become imbalanced and show that imbalance at some point in the RPM range.

I would be less worried about the other pulleys than I would abut the front seal and bearing and crank runout at the front of the engine if this had been going on for a long time.

surfinglbi23

I had one of these go bad on a 5.0 mustang build I did years ago. Simple fix but apparently its not too unusual to hear about. Who knew?

Viperbob1

Just something else to watch for as these cars age....