Well, the things you learn as you go through life, eh? Hopefully 750 ft above sea level is enough to not experience this. Thanks for the explanation, Jake! :D

Thank you for the information Jake... I will keep a spare AOS available for the next time... There will be a next time.

I installed the new AOS today and got the Jägermobile back on the road... Sure was smoky for a few minutes. I will probably change the spark plugs this weekend.

I cut the AOS diaphragm casing to take a look inside and here is what I found:

http://986forum.com/forums/uploads01...1396405124.jpg


http://986forum.com/forums/uploads01...1396405154.jpg


http://986forum.com/forums/uploads01...1396405183.jpg

The material of the diaphragm was flexible but tore very easily. There were at least three holes that were visible.

Looks like a $20 part, wonder why they cost so much?:rolleyes:

Glad you are back on the road.

It reminds me of the old vent valve on MGBs and Spridgets back circa 1970.

Someone suggested that engine braking could harm the AOS, but the greatest use of engine braking is from long descents in the mountains. Jake said living in higher elevations causes few AOS problems so I think this would imply that severe engine braking shouldn't harm the AOS.

Less atmospheric pressure in the mountains vs. sea level, less pressure differential on the diaphragm, less stress on the diaphragm.

Jager, How many miles are you gettting on each AOS? Assuming you drive consistently.
Have the intervals been shrinking?

The intervals have been approximately three years and between 62,000 and 71,000 miles. The last AOS had just over 62,000 miles on it but I have been driving harder (higher RPM average) than previous years.:dance:

Interesting my aos went right in those averages as well.

The date I purchased my last AOS was 4/8/2011.

Just so I know, If (when) mine fails how far is safe to drive while blowing a smoke screen from a failed AOS?

Shut it down immediately as there is a danger of hydro-locking a cylinder with oil, in which case a bent rod is the best you can hope for.

Danger of hydrolocking is low if the motor is running as the oil will go into the intake as a heavy vapor/mist not a full on liquid. Restarting after a tow maybe another matter as oil collected in intake may run off and pool into one of the cylinders, which is still unlikely. But better safe than sorry.

Sent from my SM-T310 using Tapatalk

Engine braking produces the highest vacuum that the system can see. All you need is a manometer to attach to the oil cap to see these things.

And its all you need to check the health of an AOS.

Jake, is this something that basically any mechanic can quickly/easily do? Don't know if you've read any of my "AOS?" thread or not. I've got an appt to replace the AOS, but they're tied up for a couple of weeks before they can work on it. I'm just curious whether I can easily figure out if it's safe/advisable to drive the car in the meantime.

Any input appreciated :)

Just get a manometer and drill / thread a tap into an extra oil cap. Some better meters record so it can be left in the trunk.

Just get one in PSI, not "WC.

Sure...but who's got "an extra oil cap" layin' around? Not me :rolleyes:

I'm a LONG way from wealthy (BELIEVE ME!), but at the moment I don't have lots of time on my hands. If having someone else quickly and reliably checking this for me is an available option, I'd jump at it.

I was thinking about this issue the other day. I replaced mine 20k miles ago at 120k and cleaned the intake interior very well. I just checked the engine a couple days ago and saw shiny wetness around the rubber boots connecting the intake plenum to the manifold. I haven't looked inside yet to see how much oil is in there, but is that a normal, or my AOS is not doing its job?

NOBODY knows the answer to this :confused:

Frodo,
You have multiple questions here. I can say any skilful mechanic can change out an AOS. You have to raise the car and work above and below the vehicle to remove and replace the AOS.
You can drive your Boxster if the AOS failure is minor, that is if the hole in the AOS diaphragm is small. I would guess many of us have driven our Boxsters for quite awhile with a failing AOS before the symptoms got worse, and then continued driving until we got the replacement part. The risk is if the hole gets bigger or the diaphragm tears while you are driving and there is a huge smoke screen behind you, shut down the motor ASAP.

Thanks, Jager. I was actually curious about Jake's statement about assessing the health of someone's AOS (as in using a manometer on it). I've got an appointment to have it replaced and was just wondering how far down the 'failure path' it had gone. Based on what I told him, the mechanic who's gonna work on it said it was okay to drive it. But wanting to avoid the more catastrophic forms of AOS failure, I was hoping to get some sort of more quantitative measurement of how bad (or not bad) my AOS really is. (They can't work on it for a couple weeks.)

Yeah, I have no doubt these guys will do a good job on the replacement. Heck, given a few hours (I'm slow but persistent) I'm pretty sure I could change it. I've just got too much going on right now to tackle it.

Thanks again.

Frodo,
It's hard difficult to say that it's safe to drive the car with a bad AOS. This will depend on how bad the leak is and if it's affecting the way the nine is running. Do you have ny CEL codes? As Jäger mentioned most of us that have had AOS that have failed didn't know it untill it was already a large leak. Best advise is to have it replaced sooner than later and ont drive it untill it's been repaired. I had my failure just 6 months into ownership and didn't even know how to access the engine. Than I found this DIY bt Brad http://986forum.com/forums/general-discussions/18090-air-oil-seperator-write-up-5.html this used to have pictures but seems its no longer available.

I do have one tip in doing this. Most new AOS comes ith a new lower hose. The clamps that hold the hose are difficult to reach. Don't bother trying to loosen the clamp for this hose. Just cut the hose using a knife but with care o you don't damage anything else in there.

Hope this helps

The car’s runnin’ great. I did get a couple codes a couple weeks ago: P1128 and P1130, which I promptly deleted using my code reader. This was because needing to do the local NE Ohio “E-Check” (emissions testing) in order to get my new registration, and the testers’ll instantly Not-Pass you if you car’s showin’ any CELs. I DID pass, though the guy had problems getting their scanner to read the data from the car (“Did you just get some work done on this, or change the battery?” I was able to answer truthfully, with a straight face, that No---no work done, and no battery replacement. I didn’t elaborate..). But as a result of that they had to do the dyno/sniff tester on the exhaust. As I mentioned, the car passed, but he did say the hydrocarbons were elevated some---inching towards the cut-off value for passing.

I don’t know, but I assume that’s related to the two codes I got on my scanner. And though it’s not hard to remove the oil cap at idle, I definitely do hear suction sounds that are louder (and stronger) than I believe I’ve ever noticed before. So yeah, I’m gonna get the AOS replaced first chance I get. Even if that happens not to be the problem, it’s due for replacing in any case..

Thanks for the tips on AOS replacement, but like I said---I'm delegatin' this go-round. If I ever get around to puttin' Jager's kind of mileage on this car, I'll have other opportunities to utilize these suggestions myself :)

Interesting. My AOS never failed, 110k miles on a 98 car. I did have a smoke cloud once but it was the result of oil overfill by my trusty Porsche shop. :(

I misdiagnosed the problem and replaced the AOS but after cutting open the original one I found it was still in serviceable condition. Oil changes every 3000 miles and lots of track duty at various elevations. I live at 1500'. Castrol 5w40