Crankcase oil

[rbutts]

I have a 79 911sc that puffs a lot of oil every time I start it, and it is oil. When I drain the oil there is more oil in the case than there is in the oil bag. So I did an experiment by draining one to two quarts of oil out of the crank case then starting it and to my amazement absolutely no smoke on start up. I've repeated this three times and no smoke . Also let the car sit and not bleed off oil and start it and it puffs quite a bit of oil each time and eventually clears up.Is there any way to fix this with out tearing down the engine and rebuilding the oil pumps.

Thanx in advance
Rob Butler

[schnellmann]

The reason for the smoke is that when the case is full of oil the bottoms of the cylinders and possibly the exhaust valves are below the level of the oil. So oil is seeping past either your rings, your exhaust valve guides or both when sitting around in your garage, driveway, etc.

Depending on where in the rotational cycle oil pump comes to rest it may let oil by from the tank into the case. This is normal and does not indicate that the pump is bad.

That said, low oil pressure (less than 1 bar per 1K revs below 3K) indicates an oiling problem. Mosquito fogging on startup usually indicates piston rings not making a good seal against the cylinder walls, excessively worn valve guides, or both.

The only real way to tell about the cylinder health without a teardown is a leakdown test (only when the engine is warm!).

You can do a cheap test on the valve guides by going for a drive. After the engine is up to normal temp, take it up to the redline in 1st or second gear and watch the rear and side view mirrors as you take your foot off the gas pedal. If you see blue-ish smoke, there's your bad valve guides. Oil will get sucked through the gaps when decelerating and burn as it travels through the exhaust, making smoke.

Good luck... and let us know how it turns out.