SpawnyWhippet

I am working on reviving a 1976 911 with an 83 SC motor, and it is somehow pumping oil into the air filter housing. After a 10 mile test drive, there was maybe half a cup full of oil in the housing What is the likely cause of this?

Crankcase pressure too high?
Oil level too high?
Some kind of valve failure?

rusnak

Is there excessive blowby? Is there a breather restrictor in the crankcase breather hose? Did you change those hoses?

SpawnyWhippet

I haven't replaced those hoses. This car has been dormant for a long time and I have just fired it up. I replaced wiring, service items and fuel hoses.

I usually work on water cooled Porsches and haven't worked on a 83 before so not familiar with the oil plumbing or how oil could get from the crankcase up to the air intake.

theiceman

Sure sign of massively overfilled
You didn't add any oil by chance did you ?
Did you know there is a special procedure for checking oil.
Has to be done with car running warmed up on level ground.

SpawnyWhippet

No, I haven't checked the oil level. It was filled by the previous owner of the car just before I got it. I will check it tomorrow and look for oil breather restrictors, thanks

rusnak

I was also thinking that but didn't want to type it.

If it were my car, I'd drain all of the oil and start over.

09mageec

+1. This is the first thing I thought of before I even finished reading the OP. Start there, it's cheap and most likely the issue. Is there any residual oil spray anywhere else in the engine bay?

SpawnyWhippet

Spot on, it was 2 quarts overfilled. I left it idling at operating temperature on level ground and pumped it out via the oil tank until it read just below Max on the dipstick. I'll take it for a test drive and see if the issue returns.

theiceman

Actually half way between min and max is best.

rusnak

^ That's correct. 180F I believe is the operating temp, but if you get the engine hotter, say over 200F then the thermostat will open all the way, and you'll see the oil level actually rise. This is actually the best temperature to drain the oil too, because you'll get a ton more oil out of the tank.

They say the correct way to check oil is on level ground, after the engine has idled for a bit at operating temperature. Carry at least 1 quart with you in the trunk.