10 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHAOS - Talk to me like a Child
Reported or suspected cause
oil hydra lock caused by faulty aos
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
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Discussions that report identifying 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.
Reported cause
A cracked cylinder or d-chunck more than likely was caused by oil hydra lock caused by faulty AOS.
Leading evidence: 'oil hydra lock caused by faulty aos' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'oil hydra lock caused by faulty aos' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Recommend specs' (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.
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Discussions that suspect a cause
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Suspected cause
A faulty AOS on the m96 engine is no joke and more than likely the beginning of the end if not caught fast and fixed....
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Discussions that contain suggestions
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Suggestion
If it is faulty, even if its not real bad if its over the recommended specs, change it out.
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
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Suggestion
The best way to know when to replace the AOS is to monitor manometer readings .
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
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Suggestion
When you decide to proactively replace the AOS, go with the UAOS.
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.
10 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: 20261027T011819Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I know this is obviously one of the well documented fixes. But could someone school me in 1) what the AOS does and 2) what is the actual common failure issue. I'd like to learn. Thanks!
Ok, I'll give you a very simplified explanation. Skip PT3 can expand on it with vastly more knowledge/corrections of this system than myself. But here are the basics as I understand it...
The AOS is the PCV system in our 996. Thats Positive Crankcase Ventilation system.
It measures out a small amount of vacuum too suck out oil vapors, water vapor, BPOC, etc and vent it to the intake. While returning liquid oil to the crankcase. But it must only use a low amount of vacuum or it starts sucking out liquid oil and directing it to the intake where it can hydra lock the engine with that oil.
When the oem aos diaphragm tears(seems the oem aos is very susceptible to ripping) or aos gets overloaded from track type use, it allows much more oil instead of just vapors to enter the intake, hence the problems...
jmo
@allcool
Great info, perfect level of understanding for me. Please keep em coming folks.
How do you know when its time to replace? Or what's the mileage at which its best?
As others have said, use a manometer to diagnosis a faulty AOS. If it is faulty, even if its not real bad if its over the recommended specs, change it out.
From what I've seen, many catastrophic engine failures can be traced back to a faulty AOS. Many engine failures blamed on other things or the unknown started with a bad AOS.
A cracked cylinder or d-chunck more than likely was caused by oil hydra lock caused by faulty AOS. Rods broken/bent, again (partial..?) hydralock possibly caused by AOS. Rod bearings hammered to death, again possibly caused by oil hydra lock caused by faulty AOS. broken rod bolts, possibly caused by oil hydra lock caused by faulty AOS, shattered piston(s)/ broken rings, yup probably caused by hydraulic lock from faulty AOS introducing oil into the cylinders.
Bore score..?,, what happened first, a faulty aos a year ago that bent rod slightly and put undo pressure on piston/cylinder wall causing it to score badly, or did the cylinder just start to score on its own,,?, ETC....
A faulty AOS on the m96 engine is no joke and more than likely the beginning of the end if not caught fast and fixed.... Porsche would change out the engine when a faulty aos was found to have caused oil ingestion, even if the motor still ran good. They knew the probability of a bent rod was high and later down the road would raise its ugly head as a engine failure.
jmo
