1991 Porsche 911 Noise in moter/transmission

Tiny
MIKEBLANKENBAKER
  • MEMBER
  • 1991 PORSCHE 911
  • 6 CYL
  • AWD
  • MANUAL
  • 450,000 MILES
There is a loud clunk when starting or when turning the engine off. I have heard it on both sides of the motor. It's been suggested that it maybe that the fly wheel is loose. I am just guessing that it may be related to the all wheel drive. Transfer case connections. Just a guess Any idea?
Tuesday, August 3rd, 2010 AT 11:09 PM

2 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Hi there,

I would be getting the drive shaft checked first.

Mark (mhpautos)
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Wednesday, August 4th, 2010 AT 2:32 AM
Tiny
CWPORSCHE
  • MECHANIC
  • 58 POSTS
If its a manual transmission then what you likely have is a worn whats called a dual mass flywheel. This flywheel contains a heavy fluid that prevents engine oscillations from transmitting thru the trans. Over time the oil escapes out causing the internal components to hit their end stops, thereby creating the knocking noise. An experienced tech knows how to check for wear. Replacing the flywheel will fix the noise.
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Thursday, August 5th, 2010 AT 11:22 AM

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