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Discussion summary
YOUR RESEARCH2004 996 MT AOS R&R cost with Trans out?
Leading reported evidence
Replace air oil separator
Performed · outcome unconfirmed
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1
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Performed · outcome unconfirmed
I have 100% replaced an AOS with the trans out without removing the manifold.
Leading evidence: 'Replace air oil separator' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check crankcase vaccum (4"~6" of h2o)' (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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Suggestion
You can use a manometer to check the crankcase vaccum (4"~6" of H2O) and that would tell you if your AOS is bad.
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Suggestion · Original poster
So why replace AOS preventively on a non track car with low miles?
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Suggestion
It would have been a lot nicer if they only charge you 2hrs or so to replace the AOS while the tranny is out.
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Suggestion · Original poster
Shop owner said no need to replace until it fails.
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.
19 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261027T025149Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Local shop (SOCAL) doing IMSB LN R&R next week. Certified/Preferred shop.
No issues with AOS but asked while trans out should we preventively address AOS?
They said no advantage ie cost savings as AOS is R&R through top of engine not front of engine.
I have heard different takes on this.
Any experts care to share.
Shop wants 1,300.00 for AOS with Trans out while doing IMSB job.
I have 100% replaced an AOS with the trans out without removing the manifold. It was a 3.4, not a 3.6 so it may make it harder. Either way, $1300 seems high. Even from the top of the engine, I have done it in 4 hours, and the part is only $150. I would think a shop could do it quicker.
Coolant tank removal and new coolant in estimate along with manifold listed on est.
1,100.00 in labor at 130.00 hr
This is with trans out.
But shop says they still do it from top of motor.
Yes, I can confirm with the tranny removed, you can replace the AOS on a MkII w/o touching the intake manifold at all. Doing it from the top takes about 4hrs if everything goes well.
Doing it with the tranny removed does save some time but not such as you would think becauue you still need to struggle with the two coolant hoses.
I just had the major services done, they charged me $234 for the AOS, $128 for the part and the rest for labor. Clutch, flywheel were parts only while everything was out for IMS/RMS.
Yes.
So why replace AOS preventively on a non track car with low miles?
Are there symptoms that alert driver?
33k mi mint condition, no issues, 6 year ownership.
For 1,300.00 I might wait for a sign of failure.
Car sees maybe 1,500 miles a year.
The rubber diaphragm that fails would be weaker with age more than miles I would think. The bottom line is that it's much harder and not as cost effective to do alone. Not to mention the damage it can cause when it fails.
I just did this and don't want to do it again (motor and tranny attached)
Shop is giving no discount on AOS labor with IMSB R&R trans drop.
Shop owner said no need to replace until it fails.
Since no cost advantage with IMSB R&R.
With my 1,500 mi average driving this car per year over the last 6 years I will likely wait.
Lol, right.
My comment does come from experience. My AOS failed and left me stranded in the worst place possible. I had to stand in the road with a yellow rag warning cars coming in both directions...I thought for sure I was going to get hit on a blind curve while everyone was traveling home from work.
Yeah.
These car make life interesting forsure.
I only drive this car to P car and other car events local.
AAA and a cell phone so I figure I am all good.
I figure if its not catastrophic and you have a sign to shut it off I'll replace if it fails.
Any symptoms you can share or early warning signs?
.
Mine started with no warning. Driving home from work and suddenly heard a screeching sound like a fan belt slipping or pully bearing failing. Got scary loud within a couple of minutes, then the cloud of smoke (thought it was on fire)
I would pull your oil cap off and listen for suction or do what the pro's do and get a manometer test done I'm sure that could give you a heads up.
I don't tend to obsess about this kind of stuff, but at the same time, I like to keep my maintenance up to date. I'd ask the smart (smarter than me) experts on this board what the worst case is with an AOS failure. If it is just a puff of smoke and you can then replace it and all is good, then your approach seems reasonable. If, on the other hand, failure could potentially result in oil dumping into a cylinder and causing hydrolock which can result in bent rod(s) or other catastrophic failure, then it might not be the best course. I'm not an expert, so I don't have an opinion. Others here may. At the end of the day, it's your car, your dime, and none of my business.
It would have been a lot nicer if they only charge you 2hrs or so to replace the AOS while the tranny is out. i wonder if there's anything special for the AOS on the AE that would prevent them from doing it from the bottom.
You can use a manometer to check the crankcase vaccum (4"~6" of H2O) and that would tell you if your AOS is bad.
Yeah, I was thinking if the X51 is any different in terms of access of AOS. The AOS is the same as any MkII.
Note the crankcase vacuum test can only be done when the engine is running. Also, at early stage of AOS failure, you may not have noticeable symptoms.
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