Oil leak - any ideas?

[key_lime]

*Accidentally posted this in the Cayman forum so re-posting it here*

Last week after discovering a wet oil patch on my driveway, I took some pictures under the RH rear of my 1997 Boxster.



It’s soaked under there – and drops about a tablespoon of oil after every journey.

After popping the engine cover off, I found the middle oil filler pipe to be wet above the flexi section, which after reading online seems like a common problem, caused by a failing AOS sucking the hose flat and cracking it. Although I do not exhibit any of the typical bad AOS symptoms, I will most likely replace this along with the filler hose, due to the unit being a 97 original (flat top).

My question to you is do the pictures suggest anything more sinister? That to me seems like a lot of oil for a small crack fairly high up in the filler hose.

Thanks

[Quadcammer]

any number of things, including the valve cover seal, the spark plug tube, cam plugs, oil getting into the intake and leaking through the plenum connectors, etc.

You gotta clean it all up really well, then go for a drive and see if you can pinpoint.

[kk2002s]

Agree clean to determine origin
Thing with fill tube, only if you were adding oil would that come into play
What about before last week, were you seeing oil?
When car is running how is the vacuum on the oil fill cap when you remove and does the engine run differently?
If you have a crack in your fill tube, that would be a vacuum leak similar to removing the fill cap.

[Geof3]

The spark plug tubes can leak and look like the valve cover gasket. The variocam ‘box’ can leak as well. I’m willing to bet spark plug tube/tubes. If so, they are pretty easy to fix/replace.

[78F350]

You definitely have to clean it. Just looking at all that oil, the source will be hard to find and it could be coming from multiple places. Replacing the AOS and filler hose are good ideas. It also would be good to replace the spark plug tubes and o-rings while you are working on it.

Here's a few pics from the gallery of leaks I've fixed on some of my 986s:

RMS and IMS seal leaking. Oil at center rear of engine and some reaching the pan if not wiped.



AOS hoses and tubes leaking:



Spark plug tubes:

[Geof3]

If you do your spark plug tubes be careful you don’t break one. They can get brittle. There are a few threads on how to make your own tool, it’s quite easy. But you do need a tool, no matter what. The good thing about oil leaks is you get to get down and dirty with your car, always a good thing. Provided of course, you fix it yourself.

[key_lime]

Thank you everyone for these suggestions

Originally Posted by kk2002s

Thing with fill tube, only if you were adding oil would that come into play

My oil currently sits at the maximum mark shown on the digital readout – maybe this, combined with the G-forces of driving is forcing excess oil back up the tube (and out) ?

Originally Posted by kk2002s

What about before last week, were you seeing oil?

I hadn’t noticed any oil leakage prior to last week, no.

Originally Posted by kk2002s

When car is running how is the vacuum on the oil fill cap when you remove and does the engine run differently?

There is also no discernible change in how the engine runs with or without the oil filler cap, and very little suction at the top of the filler tube in the trunk. I guess this would make sense if I was already losing vacuum downstream? I think it’s a certainty the tube has failed at this point, just a matter of what else

Originally Posted by 78F350

Here's a few pics from the gallery of leaks I've fixed on some of my 986s:

These are very helpful photos, thanks. I agree with you (and everyone else) with respect to cleaning the underside up before trying to fault find any further. I have a new AOS and middle filler tube on order, and will give the underbody a deep clean once I’ve got them fitted

Originally Posted by Geof3

If you do your spark plug tubes be careful you don’t break one…. you do need a tool, no matter what

I have one of these arriving tomorrow after seeing it used in a spark plug tube removal video on youtube. Hopefully it does the trick…

[BirdDog]

Originally Posted by key_lime

I have one of these arriving tomorrow after seeing it used in a spark plug tube removal video on youtube. Hopefully it does the trick…

That (transom plug) is exactly what I use to pull my spark plug tubes. About $3 at Walmart (in the boating aisle in sporting goods). They also have the t-handle ones (I bought both), but found the style you are getting worked best for me.