Please help me diagnose this oil leak...

[Kroggers]

I was on my first track day yesterday (Did my first track day today - both good and bad!!!), and developed an oil leak. It is possible that it has always been there, but gets aggravated with more aggressive driving, as I did not really have the same spectacular leak on the drive home.
The symptom came after my second drive. When I pulled of the track and stopped the car, a LARGE amount of smoke escaped from the behind my left rear arch. When looking underneath, there was oil running down onto my premuffler.

Today I removed the heater fan to have a closer look, and took these pictures. Any one got any idea where this oil is coming from??

[Doug Steinel]

As the oil temp rises on my 3.0L, the oil level in the oil tank rises. Could your oil temp on the track have risen to the point that you were in an oil overflow situation similar to the problem one has when they overfill the tank?

[Kroggers]

I never fill my SC oil level to more than half way between high and low, so would not think this is the problem. But at the moment I will not disregard anything. If this was the problem, would the oil collect here? If you look at the first picture, you can see that it was getting really wet with oil from the edge of the valve cover and up close to the second plug. And judging by the oil pooling on the rubber attached to the engine tin, I would say it was really spraying out from somewhere!!

[safe]

Has the engine always been so oily and cruddy on top, or did it become that with this leak?

Is it only on the left side and not on the right of you look between the intake runners?
I ask since my engine is the same, but not as much.
If you remove the air filter do you have oil there in the intake?

[Kroggers]

Hi Magnus, yes the engine has always been a bit cruddy on top ever since I got it. As far as I can see from the history files, this engine has never been opened in its total 210000Km. But the wet oil is new.
In response to your questions I have been back down to the car and took these pictures from the right side, and you can see that it is bone dry.



Here is a picture from the air box, and it is not completely dry. there is a very small amount of oil, but I would expect this - or is this a bad thing as well???


As a last thing, I removed the hot air fan completely and put the camera behind and took this picture - more oil


Not sure I will put the hot air fan back, I like the backdate look

[Gunter]

Look underneath at the bell housing. If there is oil showing coming out of the drain hole, it means that the main seal is leaking. When it leaks, the flywheel will throw it around.
Is the breather hose connected properly?
Breather cap gasket?
Oil pressure switch?
The picture of the inside of the air box shows oil??Overfill??
I suggest that you spray lots of engine cleaner on the area, then flush with water. When the area is clean, observe more clearly where the oil is coming from. Right now there is way too much gunk there to see clearly.
Some observations:
The sound mat looks pretty frazzled, it's a fire hazard and pieces from it can be sucked into the fan.

[Kroggers]

Thank you Gunther, that gives me a lot to educate myself on and investigate!
On the subject of the sound mat, I know it is bad and I have been wanting to remove it, but thought I had to have the engine out to do so. That is why it is still there!

[Kroggers]

Originally posted by SoCal911SC
go for the easiest and most common first -

the oil pressure sender on top of the engine.

they spring leaks quite commonly. around $10 part and easy to replace, do a search.

Thank you, I will look at this as well...

[Gunter]

Originally posted by SoCal911SC
go for the easiest and most common first -

the oil pressure sender on top of the engine.

they spring leaks quite commonly. around $10 part and easy to replace, do a search.

Common mistake!
It's not a sender; the "Oil Pressure Sender" is next to the fan post right side incorporated into the cam oil lines.
The "Oil Pressure Switch" is on top of the engine next to the breather cap (It's just providing ground to activate the oil-warning light)
There is too much oil showing to suspect the switch, more likely breather cap issues: Hose not tight?
Or worse: Main Seal?

[Kroggers]

Originally posted by Gunter
Or worse: Main Seal?

I hope not
What ever it is, it is on the left side of the engine, and only really leaks under high rpm or pressure!!!

I will take the car to a local Porsche mechanic tomorrow for an analysis, and I will take it from there...

[safe]

Main seal, is that bad or just annoying?

[safe]

If you get to much oil in the intake it will drain out somewhere???

[Kroggers]

Originally posted by safe
Main seal, is that bad or just annoying?

Lets see.....

We are trying to pay for our first house and a wedding for next August. The cost of having to replace the main seal at the same time does not sit to good at the moment. I am really hoping that this is a irritating but sensible priced fix, otherwise I can see my beloved 911 ending up in storage for quite some time...

My main problem is that I am happy to do relatively easy mechanical work, but taking the engine apart is above my skills at the moment. I plan to one day have the skills and knowledge to take my engine apart and do some nice modifications, but at this moment in time, I was even confused by the recommendations that Gunter had. I would not even know where to start looking for the "flywheel"

[Kroggers]

Originally posted by SoCal911SC
LOL on switch v. sender.

There isn't too much oil to suspect the switch. I've had them fail and leak a little, and had them fail and leak a lot. I've had one fail so suddenly and fully that I probably lost a 1/2 quart of oil in a 1/2 mile.

They have a plastic center crimped into a metal housing, and they can fail dramatically.

You almost got it in one of your pictures above. From your pictures and from the order of most common leaks from that area, the switch is definately the prime suspect.

Clean up the area really well and put a new one in.

Do you have a pic of one, so I know what to look for??

[Groesbeck Hurricane]

I'm with the breather hose (it could have developed a leak due to age), oil pressure switch, or the release valve for the oil cooler before main seal. I'd do the first two items I mentioned above and see what happens.

[Kroggers]

Thank you David, but where is the breather hose - sorry to be stupid

[Kroggers]

Thank you SoCal911SC, looks like an engine out job at the minimum...

[lateapex911]

Logically, if it were a main seal, he'd have a mess everywhere, not JUST on one side. Your wedding finances are safe, in my opinion, LOL>

The breather hose is the large black hose attached to the silver fitting to the right of the switch with the wire in that picture. To the left of the throttle linkage that appears in one of your pictures.

Because the leak is SO one sided, I *bet* it's either the breather, the gasket for the breather housing, or the switch.

Always fix the cheap and easy first!!

But..the FIRST thing I'd do is clean it up, take a spirited but short drive, and then check. It will be easy to spot before the oil gets everywhere.

[Rich76_911s]

The green arrow is pointing to the breather hose housing, with the black breather hose comming out of it:

[Gunter]

Paul:
Since some of it is a little over your head, do as planned:
Go to a Porsche shop/mechanic for diagnosis, it costs next to nothing to get some certainty here.
Wild guesses, or parts replacement without knowing for sure, is not the answer. Besides, unless you have good mechanical skills, the switch is hard to reach. It is next to the breather cap, has one wire attached to it.
The hose on the breather cap has a clamp on it and is also hard to reach.
Spray lots of engine degreaser/cleaner on the area, then use water to rinse off. Run the engine and observe where the oil is coming from.
Magnus:
Main seal is bad, and annoying. You can run with it leaking and it will just get worse.
You don't want oil in the intake; keep the oil level at mid-point or slightly lower. Oil in the airbox usually means too much oil in the tank.
(It doesn't really drain out on it's own)
Clean out the airbox to prevent the excess-oil from gumming up the runners and foul the plugs.