Rennlist

Possible AOS failure? Help needed!

Add to repair workspace

New repair projectOpen repair workspace

Original source

4 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis

THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCHPossible AOS failure? Help needed!

Leading reported evidence

Check pulleys and there was no excessive play or noises

Suggestion or failed attempt

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 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 · Original poster
I checked the pulleys and there was no excessive play or noises that would indicate bearing/water pump failure.
Original post Read captured discussion
Possible AOS failure? Help needed!

Read full discussion summary

Leading evidence: 'Check pulleys and there was no excessive play or noises' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check pulleys and there was no excessive play or noises' (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.

Read captured replies

1 matching discussions · 4 captured posts examined · 0 partial discussions

Compare 1 other evidence results

Check pulleys this afternoon

Suggestion or failed attempt

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

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 · Original poster
I will be pulling the airbox and checking the pulleys this afternoon.
Original post Read captured discussion
Possible AOS failure? Help needed!

Frequently discussed actions (2)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Check pulleys and there was no excessive play or noises

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

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 · Original poster
I checked the pulleys and there was no excessive play or noises that would indicate bearing/water pump failure.
Original post Read captured discussion
Possible AOS failure? Help needed!

Check pulleys this afternoon

No successful repair reported for this finding.

0
Reported fixes: 0
Unsuccessful attempts: 1
Discussions

Read evidence and context

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 · Original poster
I will be pulling the airbox and checking the pulleys this afternoon.
Original post Read captured discussion
Possible AOS failure? Help needed!

Coverage and how to read this overview

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.

4 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.

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

Outcome without a verified action link
Glad you get it resolved!
Original post Read captured discussion
Quoted acknowledgement is not verified as the original poster

Generation: 20261026T191851Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

Hello, my 2002 4S recently developed a sound at idle which increases in frequency as the rev's increase. I suspect it may be a failing idler pulley/water pump or the AOS. Any advice into troubleshooting would be greatly appreciated. Failing AOS? -There is a build up of oil on the intake plenum behind the throttle body but this could be due to an oil overfill that was driven for approx 10 min. (see pic attached). -The vacuum created with the oil filler cap removed -No smoke on startup or driving However the pulsing sound seems to change with RPM and I am not sure if the sound of a failing AOS would be RPM dependent. I have read that I would need to test the crank case vacuum, however I do not have a spare oil filler cap to create my own tool to test. Failing Idler Pulley/Water pump -Sound RPM dependent -No coolant that I can see yet dripping from the engine -Probably original water pump @ 96000 km I will be pulling the airbox and checking the pulleys this afternoon. I have also linked 2 videos for reference to the sound. - Idle with oil filler cap on - Idle with oil filler cap off Thank you in advance for your time.

POST 2Original post

Sounds like water pump or pulley bearings. Can remove the belt, start the engine when it's cold and run it for a short time (< 1min) and see if the noise goes away. Also spin all the pulleys and accessories by hand.

POST 3 / ORIGINAL POSTEROriginal post

Thanks for the suggestion! UPDATE: it was simply a 2" chunk of tread missing from the drive belt. I checked the pulleys and there was no excessive play or noises that would indicate bearing/water pump failure. Purchased a new belt and all appears well.

POST 4Original post

Quotes source post: 10724328

Glad you get it resolved!

This is a source reference. Confirm exact model applicability in the original material.