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Old 10-13-2013, 06:43 PM   #1
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Join Date: Sep 2013
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Oil Leak with smoke... OAS???

I posted this in the General Discussion but wondered if I would get responses on this side of the site...
I am hoping one of you with more experience with the quirks of my car (2001 Boxster 2.7 liter) can speed up my diagnostic process...

I just bought this car and have been working my way through several little gremlins.

Last time I drove it (about 8 miles) it started leaking oil and smoking severely and it looked to be coming from the passenger's side (American) of the engine (and smoked out the side cooling vent/gill) and sprayed enough that some oil onto the back of the bumper pads.

I pulled both covers off the engine and did not see any oil on the "top" of the engine like some posts I have read.

I crawled underneath and it does appear that the leak is coming from the front passenger's side somewhat close to the alternator.

I started it tonight and it definitely looks like the smoke is coming from the oil dripping on that right-hand catalytic converter. There was a big drop of oil just hanging onto the bottom of the cat.

I still can't really tell where the leak is. (I also noted the oil pan is oily but that doesn't seem to be the smoking problem - I plan to save that problem for later unless you tell me otherwise). I think I need to raise the car some more because I can barely fit underneath it (plus there are some hot parts about 1 inch from my face.)

While running, I did remove the oil filler cap in the rear trunk. It wasn't really "suctioned" on there (easier than taking the top off a pickle jar) but I did hear a vacuum release when I opened it. The engine also started to "throb" with the engine rpm's moving up and down a bit instead of staying at a steady idle (I didn't read the tach so I can't tell you the range.). I put my hand over the oil filler tube/funnel and it is definitely drawing a vacuum there. When I put the cap back on, it returned to normal idle.

I am hoping one of you guys will tell me what I want to hear...e.g., - this is easy and you'll be driving again in no time.

Could it be the Air/Oil Separator?
Could it be a Spark plug seal? (i still haven't even found the spark plugs but I did buy the Bentley book so I know I can find them.)
What's the best way to diagnose this?
Could it be an oil tube?
What's the best way to diagnose this?

Please let me know your thoughts even if you are going to tell me something rough...


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Old 10-14-2013, 05:02 AM   #2
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Location: Toronto, Canada
Posts: 190
If it was the AOS the oil leak is more internal causing the engine to burn more oil and the exhaust smoke.

The best thing to do would be to jack up the car, remove the rear passenger wheel and take a look.

You should be able to see where the leak is coming from. Check around all 3 spark plug areas, hidden behind the coils
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Old 10-14-2013, 06:00 AM   #3
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I have read that oil dripping down on the cats can come from the spark plug tubes. I would check that.

Change Spark Plugs & Tubes

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Old 10-14-2013, 08:18 PM   #4
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Location: Perth, Australia
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General de Gaulle had a 1962 CitroŽn DS that developed an oil leak and the OAS was certainly blamed for that one. ;-)

Seriously though, it might be a good idea to wash the engine down so you can see where the leak is coming from. Once it is clean except for the leak it will be clear as day looking at it from underneath whilst on a hoist. There is a hose that connects to the left side of the crankcase, crosses over to the right side under the intake manifold and plugs in to the bottom of the AOS. The oil filler tube is another suspect. A failed AOS is still a sealed unit and would just spray oil into the air intake causing MASSIVE amounts of smoke out of the exhaust.

What you are experiencing sounds like a broken hose somewhere (these are hard plastic vacuum hoses that become brittle with age and crack easily) and will be an easy and inexpensive fix once you can find it.
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Old 10-14-2013, 08:29 PM   #5
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broken oil fill tube.

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oas , oil , oil leak , smoke

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