PCV Valve

[bob8619]

i own a 1975 cadillac sedan deville, it runs rough but not too bad, today i took it on the highway for the first time and once i got home i realized it was smoking. i opened the oil cap and it appeared to be smoking from in there, it might have been over heating but i didnt smell any coolant smell, what all will cause your oil to smoke? i also realized that the pcv valve is not there, its gone. could that cause what im experiencing? any help would be greatly appreciated.

[MagicRat]

Welcome to the forum.

Virtually all diesel and 4-stroke gasoline piston engines develop a fog of oil vapor and partially-burned hydrocarbons that have sneaked by the piston rings (blow-by) in the crankcase.
This fog can look like smoke.

Furthermore, if you have not changed the oil in a while and have done lots of short trips or engine idling, your oil can be contamnated by gasoline, water condensation and byproducts of combustion. When you get the oil nicely warmed-up, these contaminats will vaporize and get 'boiled' out of the oil. Again, such vapors look like smoke.

As I'm sure you know, without an operating PCV valve, such fog and vapor will not be evacuated easily from the crankcase and simply build-up, making the situation look worse than it probably is.

IMO get the PCV system operating properly and change the engine oil and filter. If it still smokes, hook up a decent mechanical coolant temp gauge to monitor engine temp.