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996 Intermittent Knocking Sound - Help Needed

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1 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
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YOUR RESEARCH996 Intermittent Knocking Sound - Help Needed

Leading reported evidence

Run car without the accessory belt

Performed · outcome unconfirmed

No successful repair reported for this finding.

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Performed · outcome unconfirmed · Original poster

I ran the car without the accessory belt on to rule out any bearings on the alternator or water pump or anything else the accessory belt runs.

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996 Intermittent Knocking Sound - Help Needed
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Leading evidence: 'Run car without the accessory belt' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Run car without the accessory belt' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.

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1 matching discussions · 1 captured posts examined · 0 partial discussions

Frequently discussed actions (1)

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Run car without the accessory belt

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that performed work without a confirmed outcome
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Performed · outcome unconfirmed · Original poster

I ran the car without the accessory belt on to rule out any bearings on the alternator or water pump or anything else the accessory belt runs.

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996 Intermittent Knocking Sound - Help Needed
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Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.

1 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

  • Rennlist: 1 discussions

0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.

0 acknowledgements have no verified action link; they do not establish a repair result.

Generation: 20261027T005001Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

Hello all, need some help figuring out a rapid knocking sound. 2000 Porsche 911 carrera 4 just hit 90k miles. I�m wondering if anyone else has had this issue or may have an idea of what it could be. About a week ago I started hearing an intermittent knocking noise at idle. This only happens when the car is warm, there is no noise on a cold start or cold idle. Once the car warms up, it stays quiet with no knocking sound. However if the car is shut off and started again while the engine is still hot, i sometimes hear a fast paced knocking sound. It does not make the sound every warm start, but if the car is revved up a little bit even around 2-3k rpms, it starts making the knocking sound a couple of seconds after returning to idle. The knocking will stay steady for about 30 seconds, and then speed up even faster while still at idle until revved again, where it will slow back down at idle for another 30 seconds and then speed back up. The sound is not bore scoring, as I�m familiar with the sound bore scoring makes. This noise more rapid than bore scoring tick. The car has also had a bore scope and IMS done within the last 10k miles. I ran the car without the accessory belt on to rule out any bearings on the alternator or water pump or anything else the accessory belt runs. One odd thing is that the knocking can be heard clearly from inside the cabin, however I cannot really hear anything that matches that sound or pace from outside or underneath the car. The only thing that makes a similar speed noise is the purge valve above the alternator, but that makes a rapid clicking noise not a knock. You can hear the fast paced knocking sound in the video taken from inside the cabin. Has anyone experienced this before, or have any ideas what could be causing this? Thank you!!

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