8 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHSquealing bearing at engine start
Leading reported evidence
Install between the air pump and the discharge valve
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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
A pneumatic switching valve which is closed when the secondary air system is inactive thus preventing the flow of additional air is installed between the air pump and the discharge valve.
Leading evidence: 'Install between the air pump and the discharge valve' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Disconnect connector and hose' (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.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
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0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
They are easy to remove from the car, loosen three screws, disconnect the connector and hose.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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.
Suggestion
It will throw a code (CEL) if you leave it disconnected too long.
Install between the air pump and the discharge valve
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
A pneumatic switching valve which is closed when the secondary air system is inactive thus preventing the flow of additional air is installed between the air pump and the discharge valve.
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.
8 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Pelican Parts: 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: 20261026T135432Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I recently purchased a 99 911 Carrera. 6 speed manual. I love it.
I sometimes get a bearing squeal for a few seconds when starting the engine.
I think it may be a bearing from one of the serpentine pulleys.
It might also be normal if it is the Air Injection Pump. The pump runs for ~20-40 seconds on cold start to light up the cats quicker.
It lives right by your left knee when you are standing at the rear of the car gazing into the engine compartment.
Disconnect it for 1 cold start and see if the noise is still there. It will throw a code (CEL) if you leave it disconnected too long. When they start to go bad they sound like a skill saw. Sometimes you can save it ($1500) by cleaning it out when it gets really loud. They are easy to remove from the car, loosen three screws, disconnect the connector and hose.
More likely, it is the Bendix drive on the starter that is sticking momentarily on start up, which can make that type of sound. A common and easy DIY fix item, do a search, been covered many times……….
http://www.renntech.org/forums/topic...post__p__84676
courtesy Loren:
"Auxiliary air Pump
To reduce pollutants contained in the exhaust gas during the warm-up phase and to achieve the emission limits of the roll test in the USA, USA vehicles have a secondary air system. For this reason, an electric air pump has been mounted on the left-hand side of the engine compartment. This pump is activated by the DME control unit and blows the additional air through air ducts to the discharge valve. A pneumatic switching valve which is closed when the secondary air system is inactive thus preventing the flow of additional air is installed between the air pump and the discharge valve.
Functioning
If the engine is started in a temperature range between minus 10.5° C and plus 45° C, the secondary air system is activated for a period of time dependent on the start temperature (min. 50 seconds, max. 179 seconds).
The secondary air system is only activated if the following engine-related operating conditions apply:
- Engine load (TL) between 0.7 ms/rev, and 4.7 ms/rev.
- air mass (ML) not greater than 300 kg/h
- Engine speed between 680 rpm and 2,800 rpm
- Altitude adaptation factor greater than 0.76 corresponding to less than 2,400 meters above sea level."
I remember another post as well that explained the running of the pump after cold startup (example at stop light after warmed up), but my guess is in the functioning sections, if those conditions apply then it will run, as I and others have observed.
Just cruising thru this forum and noticed this post from Wayne. Sounds like a match to me.
I'd park it until you can rule this out.
http://forums.pelicanparts.com/porsche-996-997-forum/543614-if-you-think-ims-bearing-failures-all-myth-then-check-out.html
This is a source reference. Confirm exact model applicability in the original material.
