BIG DILEMMA,......... recently I purchased a 1991 750iL with under 140K miles on it.
At the time of the purchase I was informed, it (the engine) had low compression in one of it's cylinders, ran little unstable at low RPM's, but highway driving was "no problem"
After receiving the car, I started it up without any difficulties, it starts perfect every single time.
While in idle it's little shaky but as soon as you press the gas it accelerates real good.
Now the scary/funny part,..............
As soon as the engine warms up to it's working temperature it starts blowing a lot of smoke, smelling like a burned oil.
While in motion and not going too fast you can observe the exhausts in your rear view mirror.
Waiting for your traffic light to change, it (the smoke) "sneaks up around you" and you can smell it like over done fish being scorched on a frying pan.
The engine does NOT overheat at all, simply smokes a lot due to that one allegedly low compression cylinder, straight out the tail pipes.
My BMW dealer says it can be a number of causes, beginning from bad piston, stuck valve, bent lifter, busted-cracked ring on the piston all the way to blown head gasket ( which I doubt, given absolutely no presence of oil in coolant and vice versa. Of course they, the Dealer haven't seen the car yet. They want to, for a small fee of $300.00 just to diagnose the problem. I will wait a while on this one
In my UNPROFESSIONAL opinion it must be the ring going bad , not sealing the piston in the cylinder causing loss of compression, leakage of lubricating oil into the chamber where all the fuel explodes etc etc.
Other than that, engine is dry, clean, smooth running aside from that tiny hardly noticeable vibration at low RPMs
I JUST WANT THAT SMOKE TO GO AWAY!
IT IS QUITE EMBARRASSING, not to mention being bad for the environment type of situation.
Plus, I'm worried the problem can get worse, will it?
Some say no! but then who knows? we're dealing with one of the most advanced and complicated pieces of the automotive industry.
PLEASE, I NEED YOUR ADVICE AND HELP..................
e-mail as well as forum responses are more than welcomed.
THANKS IN ADVANCE............... BMW lover