39 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHAOS life expectancy?
Leading reported evidence
Install sometime in 1998
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
Unsuccessful attempts
1
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Performed · outcome unconfirmed
My AOS is the original from factory....installed sometime in 1998 with over 110K miles now....I do not track the car, 95% highway miles on my commute to work (about 80 miles round trip)
Leading evidence: 'Install sometime in 1998' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'freaking labor required' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check issues' (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.
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Performed · outcome unconfirmed
Replaced an AOS (smoke from the exhaust) with OEM part 1k miles ago, failed on me with a squeal from the engine bay.
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Performed · outcome unconfirmed
At 120kkms I replaced the AOS due to a coolant leak no other visible signs of pending failure.
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Performed · outcome unconfirmed
, but they did make us suffer the agony for about two decades, and many an engine was replaced due to it.
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Performed · outcome unconfirmed
My AOS is the original from factory....installed sometime in 1998 with over 110K miles now....I do not track the car, 95% highway miles on my commute to work (about 80 miles round trip)
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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 · Original poster
No problem when removing the oil filler cap with the engine running, came off easily so doesn't appear to have the vacuum symptom, (But it does stumble badly with the cap removed.).
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.
39 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261027T020439Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
My 04 has about 25,000 miles on the AOS (same mileage since the engine was rebuilt by a well respected engine builder). But now seeing more blue smoke at start-up and oil consumption is steadily increasing (last 1700 miles averaged under 550 miles/qt). No problem when removing the oil filler cap with the engine running, came off easily so doesn't appear to have the vacuum symptom, (But it does stumble badly with the cap removed.). At last years full service at my indy he said the AOS tested fine.I run with the oil at the half mark. DT40 changed 2x/year. Engine not run regularly at high RPMs (which is my problem).. Coolant s perfect. So is the inside of the oil filler cap. But, how long should the AOS last, is it possible it is starting to fail?
I've gone through 3 in 3 year in less that 6000 miles. Depends on what you are doing with the car, but I would not be surprised if it is starting to go after 25,000 miles.
I have to replace one right now with 3,000 on it. Only noticed it when my son saw puffs out both pipes under high rpm shifts. 12� H2O confirmed it! Perhaps the AOS being made today has the quality creep associated with Porsche no longer using them on production line. The one I�m replacing is genuine �Porsche�. Total crap part and such a royal pain to replace ($$$ labor).
Rennvision has a good video on testing the AOS. Guess I need to have that done. I'm concerned about the increased oil consumption and bigger puff of smoke at start up.
Seems like a shoddy part now.
Kris's experience is exactly what keeps me from preventatively replacing mine. Seems to be a common issue with replacements failing either immediately after replacement or shortly afterwards. I just keep testing as in Jake's video and watching for signs in the meantime.
Are these the Porsche-branded AOS that have the failures or a after-market brand?
Testing is good but failure sounds like it means repeated failures.
And that's a $1200 job.
My AOS is the original from factory....installed sometime in 1998 with over 110K miles now....I do not track the car, 95% highway miles on my commute to work (about 80 miles round trip)
If you're really worried about the stock (plastic) AOS failing, it might be with the extra $500 (for the part itself - labor remains equal) to go for the "Motorsport" AOS...
** Edited for accuracy... Seems like it's much more than $500 difference. Looks like the LNE adapter is $850 by itself...
I can think of many reasons why it hasn't happened, but with the wide variety of aftermarket parts for these cars, it seems odd that nobody has made an aftermarket "performance" AOS. It seems pretty simple in function, and if a manufacturer could make a bulletproof version that retailed for less than the motorsport version, it seems like it could be a winner.
I'm not sure - I don't remember if he did or not. I do know that when they built my motor (stage II 3.8l) they did NOT offer it as an option (they do offer many extras or options). So it's very possible you recall correctly
It seems like it could be a good business venture for someone with the proper engineering skills and inclination. I've been thinking about getting mine replaced proactively but this thread has me rethinking that. As a Tip Cab, mine would be an engine-out procedure. I have no symptoms and it passes the manometer test. Currently at 70k miles.
My Stage II has a factory AOS, replaced during the rebuild. It sounds like the newer one aren't the quality of the originals. The cost of the Motorsports version is right up there with the labor cost, wow. Maybe I should look for an old salvage one :-)
I'll have mine tested right after the holidays, off visiting family now, and see if it's failing. I think that would be the best answer for the oil consumption issue.
I wouldn’t worry about the AOS until you get symptoms. You know the signs and how to check for issues. I had no clue mine failed until this:
Apparently some serious crankcase pressure on up shifts...
I have a solution for this that I have been working on for a month or so. I have been waiting on parts to arrive, and the holidays to be over to finish it. Should be finished in a week or two, I'll post a new thread when done. It retains the Factory AOS, but eliminates the need to replace it, but at the same time still works as designed ...
I can't take credit for this, it was a Christmas Gift from the Porsche Gods. They spoke to me after I was reading a "AOS Mod" thread a month or so ago , and the statement was made that all the great Porsche minds on earth had failed to come up with a solution. The Porsche Gods gave me the solution.
Dr h.c. Porschetech3
Not typical, but 99.9% of the time that my car is running, it is on the track. The AOS really does not like the track. All of mine have been Porsche AOSs.
Replaced an AOS (smoke from the exhaust) with OEM part 1k miles ago, failed on me with a squeal from the engine bay. Got a free replacement under warranty. Hopefully the new one lasts a little longer.
All well and good about warranty for new part. However, the devil in the 996 AOS issue is the freaking labor required for the engine drop with what should only be a 3 hour job like on the 997. Even going in over the top of the manifold takes a whopping good bit of time (not to mention high risk of breaking vacuum lines).
It hasn't been very difficult for me, I've done it twice so far. Removing the top mounting bolt from the intake area, and accessing the bottom mounting bolt from under the rear control arm, has always made it easy. I takes 4 hours at the worst, maybe a little more if the alternator doesn't want to play nice.
