Planet 9

**Slatfatf** · #**281** 04-14-2009, 10:12 AM

Originally Posted by andy987s

I hit the dreaded oil ingestion problem a week ago and am now researching my options. I just have to say what a brilliant resource this site is. Will post my own results back here when it's done. Thankyou everyone for all the good work.

Everything you need is in the 2 articles: Improved VOS and Air Pump Mod

andy987s · #**282** 04-15-2009, 11:25 AM

Originally Posted by Fort Felker

Everything you need is in the 2 articles: Improved VOS and Air Pump Mod

Thanks Fort.
I rang Andy Stack at rennsport to discuss the Oil Ingestion problem and accepted his offer to come on down and have a look at one of our engines and the VOS. He ended up dissecting one and voila! I saw something I suspected ever since reading BillC's post.
The diaphragm had a perforation. I think this is a vital part of the issue.

Once the diaphragm is perforated a little spring will keep the VOS permanently open to the plenum. My theory is... When there is an oil surge from a hard brake and left hander coupled with a high vacuum pressure (caused by shutting the throttle abruptly at high rpm), the VOS will no longer be able to return liquid oil to the sump via centripetal and gravitation forces. Instead some of it will be sucked into the plenum and cause a lot of concern all the way around. You see when the diaphragm is intact the high vacuum will temporarily close (or at least reduce the communication) with the plenum and thus not suck liquid and allow the VOS to do it's thing and separate out the oil and return it to the tank.

I've taken a whole bunch of pics and will put them into an article along with a description of how the VOS works and the PET diagram. Then go and test the theory with my car and post back the results. Has anyone looked at the diaphragm in the Motorsports improved VOS (IVOS), or have an old one that could be dissected?

Andy

**jcriggs** · #**283** 07-14-2009, 08:41 PM

Originally Posted by andy987s

Thanks Fort.
I rang Andy Stack at rennsport to discuss the Oil Ingestion problem and accepted his offer to come on down and have a look at one of our engines and the VOS. He ended up dissecting one and voila! I saw something I suspected ever since reading BillC's post.
The diaphragm had a perforation. I think this is a vital part of the issue.

Once the diaphragm is perforated a little spring will keep the VOS permanently open to the plenum. My theory is... When there is an oil surge from a hard brake and left hander coupled with a high vacuum pressure (caused by shutting the throttle abruptly at high rpm), the VOS will no longer be able to return liquid oil to the sump via centripetal and gravitation forces. Instead some of it will be sucked into the plenum and cause a lot of concern all the way around. You see when the diaphragm is intact the high vacuum will temporarily close (or at least reduce the communication) with the plenum and thus not suck liquid and allow the VOS to do it's thing and separate out the oil and return it to the tank.

I've taken a whole bunch of pics and will put them into an article along with a description of how the VOS works and the PET diagram. Then go and test the theory with my car and post back the results. Has anyone looked at the diaphragm in the Motorsports improved VOS (IVOS), or have an old one that could be dissected?

Andy

Any update yet?

Globespy · #**284** 07-20-2009, 03:16 AM

What is the incidence of this problem in 987 boxster S compared to cayman? Is it just as likely to happen in the boxster? I have owned my car for 2 months and have not seen this issue....fingers crossed.
Anyone from the local Seattle area had this problem fixed, and if so, who by?

I am truly concerned by this thread and the entire issue. Having come from an M3 to the boxster, I'm starting to really think hard about why BMW call themselves the ultimate driving machine.....I mean, despite being 'designed' for a track or not, my M3 had none of these issues. It almost seems like Porsche made these things way too delicate.....even for spirited driving on public roads using high performance street tires.

It makes the entire Porsche experience somewhat sour knowing that the car may not be able to handle spirited driving on public roads using street tires.....

Capercat · #**285** 07-20-2009, 04:13 AM

Originally Posted by boobernackle

at about 10-12 hours of labor, you can pretty much guarantee that Porsche will not provide a fix for the current Cayman owners. No recall, free fix, or any other goodies will be provided. Porsche will address this as a "new feature" for the upcoming Cayman only, which means they are not describing the current cars as being flawed.

In english, this is called getting "shafted" by Porsche.

Indeed, I know of a specialist American Printer manufacture that shares the same philosophy. Rather spend time & money in correcting faults in current models, they will learn from it and redesign the fix in the next model. However printers are a lot cheaper to buy than Porsche cars. This is a common approach, hence why I usually wait to purchase second generation cars.

beez · #**286** 07-20-2009, 10:47 AM

Originally Posted by Globespy

What is the incidence of this problem in 987 boxster S compared to cayman? Is it just as likely to happen in the boxster? I have owned my car for 2 months and have not seen this issue....fingers crossed.
Anyone from the local Seattle area had this problem fixed, and if so, who by?

I am truly concerned by this thread and the entire issue. Having come from an M3 to the boxster, I'm starting to really think hard about why BMW call themselves the ultimate driving machine.....I mean, despite being 'designed' for a track or not, my M3 had none of these issues. It almost seems like Porsche made these things way too delicate.....even for spirited driving on public roads using high performance street tires.

It makes the entire Porsche experience somewhat sour knowing that the car may not be able to handle spirited driving on public roads using street tires.....

The 987 Boxster can be just as susceptible to this as a Cayman, but I've not seen or heard any reports - even on the boards here - of this happening during spirited driving on the street with a stock car on OEM street tires.

brad

obsessed · #**287** 09-26-2009, 07:58 AM

Originally Posted by K-Man S

Looper is correct, read my posts above, it CAN and DOES happen on the street under the right conditions, basically any time your cornering exceeds the ability of the AOS to keep oil from getting into the intake.

I might also add that 997S's don't do this on the street or track...

Actually, I'm reading this thread as I am having the start up smoke cloud problem with my 997S after hard sessions on hot days. Idling for 5- 10 minutes does not seem to help. After reading this, I wonder if idling with its higher vacuum may even worsen the start up smoke problem.