My April 1998 build date Carrera 2 has been having a cold start knock since I bought it in 2015, The noise would appear a few seconds after startup, and only at idle. It would go away after a few blocks but would often reappear after a few hours of the car sitting. Today while I had the car on a lift I noticed the coolant pipe in front of the sump plate moved in its clamp and when it did it made a noise similar to my knocking noise. The clamps along the side of the motor did not move. Sadly these clamps are welded shut so putting a rubber shim between them and the pipe is impossible. I sprayed with Plasti Dip on the coolant hose and let it cure up some before sliding back in place. Too soon to tell if its been cured but so far its been silent. Picture is of the clamp pushed aside from where it was clamped you can see the marks from the vibration.
Discussion summary
YOUR RESEARCHEarly 996 cold Knocking source?
1 matching discussions were examined; no attributable action/outcome evidence was detected. No consensus or repair conclusion is claimed.
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3 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
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Generation: 20261026T142254Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
That clamp should be welded to the pipe and not movable at all.
I�ve heard at least another 996�er having a knocking sound at cold start that was related to coolant pipes.
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