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Discussion summary
YOUR RESEARCHAOS boot/ bellow failure? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Leading reported evidence
Replace by a uro and the bellow cracked
Performed · outcome unconfirmed
No successful repair reported for this finding.
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0
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Performed · outcome unconfirmed
I had mine replaced by a URO and the bellow cracked.
AOS boot/ bellow failure? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
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Leading evidence: 'Replace by a uro and the bellow cracked' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'over filling the oil system in these engines' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Fill oil system in these engines' (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 performed work without a confirmed outcome
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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.
Performed · outcome unconfirmed · Original poster
My full AOS was replaced by the dealer 2 years 15/miles ago.
AOS boot/ bellow failure? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Test okay
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
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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
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AOS boot/ bellow failure? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
over filling the oil system in these engines
Suggestion or failed attempt
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
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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 suspect a cause
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.
Suspected cause
The part isn't as "fickle" as you might imagine; by far, its biggest problem is over filling the oil system in these engines.
AOS boot/ bellow failure? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Fill oil system in these engines
Suggestion or failed attempt
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0
Unsuccessful attempts
1
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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
The part isn't as "fickle" as you might imagine; by far, its biggest problem is over filling the oil system in these engines.
AOS boot/ bellow failure? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Recommend lowering the oil levels two
No successful repair reported for this finding.
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Discussions that contain suggestions
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion
Several years ago, Porsche NA issued a tech bulletin recommending lowering the oil levels two to three bars below the full mark on the dash display, and even released recalibrated dip sticks for cars still equipped with one.
AOS boot/ bellow failure? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Replace aos along
No successful repair reported for this finding.
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Discussions that contain suggestions
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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
If yours is leaking, yes you have to remove the AoS to get a it, and I would HIGHLY recommend replacing the AoS along with the boot, and ONLY USE THE FACTORY AoS, NEVER AN AFTERMARKET UNIT.
AOS boot/ bellow failure? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
Use factory aos, never an aftermarket unit
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
If yours is leaking, yes you have to remove the AoS to get a it, and I would HIGHLY recommend replacing the AoS along with the boot, and ONLY USE THE FACTORY AoS, NEVER AN AFTERMARKET UNIT.
AOS boot/ bellow failure? - 986 Forum - The Community for Porsche Boxster & Cayman Owners
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.
13 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
986Forum: 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: 20261026T152433Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I see some oil dampness on the right side of my engine. I think the lower boot bellow for my AOS is leaking.
Is that something that can be changed easily? Or does it require the entire AOS to be removed?
I don’t think I have a bad AOS. It was changed at the dealer 2 years, 15k miles ago. I have no symptoms of AOS failure.
2001 Boxster S
First, I'd remove the wheel and check if the leak looks more like it's coming from a spark plug tube.
My opinion - The bellows is the difficult part of swapping the AOS. The rest of it is easier to reach. If it's possible to install the bellows with the AOS still installed, it would be a lot more work than removing it and installing it correctly.
I did this video a few years ago and it may help you visualize the situation.
Yes, these boots can and do leak. If yours is leaking, yes you have to remove the AoS to get a it, and I would HIGHLY recommend replacing the AoS along with the boot, and ONLY USE THE FACTORY AoS, NEVER AN AFTERMARKET UNIT.
Thanks for the video. That gives a lot of context.
My full AOS was replaced by the dealer 2 years 15/miles ago. All the rubber should still be good and not hardened. I am thinking of maybe re-seating the clamps. Maybe something is up with the sealing surface.
I would hate to think that OEM parts installed by the dealer failed so quickly.
Bump.
Agreed 100%. I had mine replaced by a URO and the bellow cracked. So much for a replacement
Mine is in the shop this week to have it replaced.
Edit: For context, I had my AOS replaced in 2019. Since 2022, it's mostly seen DE days with my local PCA so it gets driven hard.
I think the dealer didn’t install my clamp properly. I got 2 new clamps on the same boot and it’s holding properly now. It was really a pain to do. But got it done.
Miles and age are not necessarily the only factors when it comes to replacing an AOS. How you drive can also determine health. Long runs in the upper RPM range can tear the membrane inside the AOS. Some tracks I run will go thru an AOS regardless of how new or old it is. The roval at Kansas Speedway is a perfect example. Driving NASCAR T3 was 5K+ rpm in 4th gear and T4 thru the main straight was 5th gear at 5K+ rpm. There wasn't appropriate time or locn to upshift so the AOS sustained very high rpm for the majority of the lap. It was toast after 2 days.
The part isn't as "fickle" as you might imagine; by far, its biggest problem is over filling the oil system in these engines. Several years ago, Porsche NA issued a tech bulletin recommending lowering the oil levels two to three bars below the full mark on the dash display, and even released recalibrated dip sticks for cars still equipped with one.
Those of us out in the field that see these cars everyday had begun lowering the oil levels slightly because we found it addressed two common problems:
The occasional "smokey startup" was dramatically reduced and even eliminated.
The life span of the AOS increased significantly.
JFP - Thanks for this.
Is there a part number for the recalibrated dip sticks? Or is this not applicable to the 986?
Update: Turns out only the boot / bellow was torn and there were signs of oil on the side. The AOS itself tested okay.
