7 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH1999 C4 AOS Quetions
Reported or suspected cause
air oil separator
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
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 report identifying a cause
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.
Reported cause
Yes i had this problem it mix water in oil it was the AOS
Leading evidence: 'air oil separator' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'air oil separator' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Disconnect coolant pipes and hooking them together' (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.
Disconnect coolant pipes and hooking them together
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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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
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Suggestion · Original poster
One tech article mentions disconnecting the coolant pipes and hooking them together
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.
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.
7 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: 20261026T174436Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Could the oil and water mix in my engine actually be caused by a bad AOS unit ?
One tech article mentions disconnecting the coolant pipes and hooking them together
to by-pass the AOS as a test
Anybody have any additional info. on this procedure ?
Are there coolant pipes (hoses) connected to the AOS
I am not sure that I see them in the diagrams of the AOS
Need some sage advise on this one
thanks
Yes, because there are coolant passages in the upper section of the AOS, intermix via the AOS is possible, but not very common.
Before even thinking about trying to by-pass the coolant lines, you need to know that even getting at the AOS on a 996 can be a bear, so if you think it is leaking, just change it out rather than try to jury rig a by-pass. It can be done with the engine in the car (
http://www.renntech.org/forums/tutorials/article/238-air-oil-separator-replacement-aos/
), but it is easier and quicker to drop the engine if you have the facilities.
That said, judging by your other thread about the oil cooler, you may have to seriously consider that you have a cracked head, which is more common than and AOS intermix.
Check this thread:
http://forums.pelicanparts.com/porsche-996-997-991-forum/841557-1999-c4-oil-cooler.html
Post #2 in the other thread that you started about this has a link where it did turn out to be the AOS.
