Oil leaking from bottom of air filter housing

Claran - welcome to Planet-9, the friendly Porsche Forum..

Most likely, but clearing it off and dust with baby powder to see the trail of the oil.

BTW - please visit New Member Introductions and introduce yourself and your car. Photos are good.

I'm also going to move your thread into a specific forum for problems.. posting it in the general "chat" area isn't all that great for tech questions.

Thank you. New here, so, not sure of the rules. Thanks for the tip. Never thought about using baby powder. I intend to change oil and filter and clean the entire area this weekend. I'll give it a dusting then.

CiaranD, do you get smoke on startup? With all the oil in your air box, which could only get there by the back flow on deceleration. You wonder about the mass air flow meter which is between the throttle body and the air filter, which is probably coated with oil. Just thinking about where the rest of that oil is going under acceleration. Maybe on the back sides of the intake valves. Please confirm that the AOS is bad by having a vacuum negative pressure gauge done from the oil fill port.

I only got the car on Sunday. Took it a quick run then parked it in the garage. Started it today for the first time and it smoked for 5- 10 minutes. Bear in mind, it's cold here atm, only around 4°Celsius. The smoke wasn't oily smoke and it didn't smell bad in any way so, I'm assuming it was just the cold weather. I'll get tinkering this weekend and post back findings.

Open the air box and replace the filter. Check the big hose that goes to the MAF and clean the oil out of that large hose. Do not try to remove oil from the mass air flow meter as its too sensitive, even to fluids that are specific to cleaning the mass air flow meter unless you discover the exact Porsche one. Once it sends a warning message to the ecu you will need to change the MAF out.
Check out the licence plate area for oil droplets. If you find any that may mean the catalytic converters are coated with oil as well. That oil will eventually burn off the converters if you change the AOS.

Thanks Apex. I'll dig in this weekend.

Don’t fill the oil to the full line, keep it one bar below. If you do that and clean out the intake per above I bet it will fix the issue. Even with a good AOS I was getting oil in the intake until I just filled it a tad lower.

I’ve hosed down my MAF with MAF cleaner a couple times without issue, and that’s the first I’ve heard of it being sensitive to that. But YMMV.

Quick question... do you know if your car has been desnorkled..? Can make a difference to how much moisture enters the air filter housing in my opinion. I had my MAF cleaned and they are fragile inside, just be careful.... it does make a difference to how the car runs too.

Just track the oil backwards. Mine has almost 0 oil in the air cleaner and I use motor compression braking a lot.

Yeah, I intend too. Hadn't noticed, until I got the car, just how demanding the wife and kids can be. Lol.

Take care of those assets, she may help you later get what you really want after the luster of the Cayman wears off.

Apex1 said:

CiaranD- Any progress with the oil in the filter box? You got an interesting situation as your engine is port injected, which means that the AOS is more like the M 97 models, I believe. At any rate its most likely failed. A manometer can let you know how much vacuum it is producing. Don, you are the expert on these motors, what vacuum level should he see using the vacuum gauge? I would think, Porsche put the 9A1 3.4 motor AOS on your 2.9 engine. Don what's the final word here?

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Unfotunately, I don't have a vacuum manometer so I can't say. I haven't looked to see if the 2.9 and 3.4 share the same AOS, but the replacement instructions are the same... so they probably did. Unfortunately the 2.9L AOS won't fit earlier engines, they made it much easier to swap out (meaning it probably won't need swapping out) and changed how it connects to the engine over the earlier engines.

Apex1 said:

Take care of those assets, she may help you later get what you really want after the luster of the Cayman wears off.

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I hear ya!