Help please

On my 1996 328i theres a breather pipe running from the front of the tappet cover. With this connected the car smokes like a coal train, however if you disconnect it, no smoke. Any ideas. Theres a brand new factory shortblock fitted, so i believe it cannot be rings, also the head has been done over so valve stem seals should not be a problem.
The car was going very well for about 10000 km and all of a sudden the smoking started.

regards

How can a breather tube affect the smoking. There is no connection between them unless there so much pressure in the crank case that in blows oil into the intake. Whats the color of the smoke?

Smoke huh? My 1992 318Is was smoking when I mashed the gas pedal and the RPM's hit about 5k. When I mean smoke I mean smoke screen! I was about to pull the head and check for a blown head gasket or worn rings. This guy at Autozone told me to put in some Head gasket sealant into the radiator. I can't remember what it was but it was in a silver bottle and i think it was made by Gunk...not sure. I put this in and followed the instructions completely. Takes about a day to do it right. Well low and behold.....my car doesn't smoke anymore! I couldn't believe it. I have 164,000 miles on it now. I'm not getting rid of this car for nothing now...it runs like brand new. I'm not sure if this is going to fix your problem or even pertains to your problem but it never could hurt to hear what others done to their cars.