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-   -   Loud knocking sound / different symptoms! (http://986forum.com/forums/showthread.php?t=76156)

palmhero 09-06-2019 09:28 AM

Loud knocking sound / different symptoms!
 
Yesterday my 986 2.5L started to knock from the back / (subjectively right side).

Symptoms:
- audible only if in gear and moving
- NOT happening when cruising on neutral
- NOT happening / stops to knock when clutch is presed
- NOT happening immediately from start, only when car warms up
- more audible when climbing a steep hill
- I can also hear very similar sound but not so loud when I lower the right side of the car from being jacked up.

Visual inspection shows no rattle or damage on CV axle joints, I have old bushings (140k mileage), but I don't think they would hit so loud. It sounds somewhat like someone hitting wood with a hammer somewhere in the distance, but with force.

palmhero 09-06-2019 09:29 AM

yes, also: knocking is synced with wheel rotation. Same speed of knocks when in 1st, 2nd, or 3rd gear but the car moving at same speed.

Anker 09-07-2019 02:07 PM

Bad universal joint on the rear axle.

palmhero 09-07-2019 02:09 PM

Where is it located and what to look for when inspecting it?

rfuerst911sc 09-08-2019 02:42 AM

In your original post you stated " Visual inspection shows no rattle or damage on CV axle joints " please explain exactly what you did or what this means . The axle universal joint mentioned above is the same thing as the CV axle joints . Usually but not always the first sign is the CV joint rubber bellows/covers are torn and throwing grease in the wheelwell or under the chassis . But a CV joint can be bad and still have good bellows . Classic symptom is a clicking or knocking noise as the axles rotate .

palmhero 09-08-2019 02:45 AM

I'm changing the "coffin arms" with bushings next week, will buy an axle joint from a dead 986 I found nearby to have it in the trunk when I'm doing the bushings. I'll remove the CVs and examine them.


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