Ok folks I would like to hear worst case/best case scenario. I drove the '04 996 to the store this morning without a problem. I go to pick my son up from school no problem. On the way home about a block from my house I notice a white cloud of smoke in the rearview. Pull away from a stop sign another white cloud. Smoke appears to be coming from the exhaust with no oil leak detected. I'm not a wrench guy so it will be towed to my indy tomorrow. I guess I am just hoping something simple but know it could be the $20,000 question. A few things original IMS, 67K miles, low oil consumption 1/8 quart/500 miles, no complaints other than the dang foam from the A/C vents.

TIA

Tom

 

If it's happening repeatedly, you may have blown out the membrane in the AOS. If this is the case, it's _possible_ that you could eventually suck enough oil into the intake to cause some engine problems.

This is one of those rare times where - since you said you're not comfortable diagnosing it yourself - the tow truck doesn't seem so ridiculous.

Rather than freaking yourself out about the worst-case scenario, just assume it's the AOS or some other relatively inexpensive and curable issue. Otherwise, you're just going to put together a list of potentially awful thing and stare at it all night, finally falling into a fitful, restless sleep with visions of stacks of $100 bills flying out of your wallet.

 

I only drove it less that .2 miles after seeing the smoke and shut it down as soon as I got home. There was a heavy burnt oil smell in the garage after shutdown. I hope it is as simple as an AOS issue. I also thank you for the input. I literally have tears in my beers pondering the worst case.

 

Oh I feel your pain, AOS is not super hard to diagnose, start the car and then pull the oil filler cap. If there are issues you see a big difference in idle, it should pull a bit of vacuum, if its failed you get a much bigger vacuum.

Pelican has an article here:

http://www.pelicanparts.com/techarti..._Separator.htm

If not that then scored bores would be my guess. (Sorry). Fingers crossed for AOS, PITA to replace but way cheaper than a engine rebuild.

 

Tom,
Before you panic, let's do some simple diagnosis?

1.AOS- the tests are simple ,inexpensive and conclusive. Search digital manometer. Much else is amateur speculation in my experience(I'm good at that too !). There is a test hack to disconnect the AOS hose(Pelican).If it is the AOS the plenums will be coated with oil and will confuse any fix unless that is cleaned up as part of the repair.
2. Do a compression and leakdown test. You'll probably find a long extension tube useful. We are looking for one or more cylinders wildly different psi.
http://www.ebay.com/itm/Engine-Compr...UAAOSwTyZZeWon
3. Look for Intermix -Search for how - it is easy
4. Check all codes. Particularly look for a Misfire code on one cylinder.A cheapo code reader will do this.

Give us the test results and it should be possible to give you a fairly confident focused diagnosis.
Meanwhile the talk of new engines may amuse the bystanders but sure it won''t help you much -yet ?
Don't let an inexperienced(with M96)mechanic near it ! The M96 is NOT just another engine -it has (potentialy expensive) quirks. Which is why the Forum is here for you.
Good luck with your repair Tom.

 

Thank you for the advice sir. I started the car today just long enough to back it out of the garage for the flatbed. It was a smoking mess. I sent it to an indy recommended by PCA. He has over 45 years Porsche experience. He is thinking AOS from the description but said it will be Monday before he can look at it. Many of you are awesome wrenchers and many are like me that have to pay to play. I will certainly update you guys when I get the call. Thank you again for calming the nerves a bit and giving me hope this may not be catastrophic.

 

Smart move shutting her down & flat bedding it to an indy. GL Tom, ideally it's an AOS issue that was caught in time .

 

Spot on. Indy called today and it is an AOS failure. Not inexpensive but a lot less than $20,000. Hope to be up and running in two days for a little enjoyment of the Houston Fall weather topless. Topless is the car not me that would just be ugly.

 

AOS functionality test tool is $30 diy -all in Search.

 

I'm not sure I understand what you're saying - do you mean that IF I blew out the membrane on the original AOS, that might cause the NEW one to go bad, suddenly? Or are you saying I could have already blown the membrane on the new one? How could that have happened? Thanks -

 

You have been in here since 2018? You must have not been reading the "Technical Threads". The AOS has been thoroughly discussed ,dissected,, and even redesigned with a new updated Improved System

 

I am unsure your post got added where you intended (or to the suggested thread below it) but it's the latter.
From what I read on here sometimes the membrane nside the new AOS fails shortly after it has been put in.
I guess it's due to bad quality of the replacement part or due to the membrane already deteriorating sitting on the shelf (not very likely imho).

The UAOS developed by Porschetech3 addresses this by making replacement of the valve (where the membrane sits) far less time consuming than time required for R&R of the original AOS.