mtler

Hi folks,
I have searched the web for BMW N52 oil separator and didn't find any conclusive solutions or ideas how to check if it's bad.
Perhaps you guys know some simple tests or facts that can pinpoint to a defective unit.
The engine is a 2006 N52, which has the external oil separator.


When the engine is idling, if I open the oil cap, should there be vacuum or pressure coming out?
I have an abnormal oil consumption, I don't have any evident leaks, as I have already replaced the oil filter housing gasket, the oil cooler gasket and the valve cover gasket.
The car doesn't puff any smoke during normal driving. My tailpipes are clean on the outside, so is my back bumper. Car is a 2006 with 135k miles.
Forum posts on the web suggest the oil separator when there is an oil consumption problem with no signs of leaks.
What do you guys think?
Thanks for your input !

pcy

There is no way to open that oil separator without breaking it. I haven't seen any info w.r.t testing it.

I have replaced it as a preventive maintenance at around 125K miles [while I had the intake manifold out for replacing the starter].

My suggestion to you is to go ahead and replace it along with the 2 hoses [that connect the oil separator to the valve cover on the top and oil pan at the bottom].

pcy

New OEM oil separator is about $100 (not sure about Canada dealers' prices).

mtler

Thanks for your reply pcy.
The oil separator is about $200 CAD here.

My question to you is: When you open your oil fill cap while the engine is running, do you have vacuum or pressure? Should it be vacuum or pressure?

And the oil separator`s job is to take the engine`s oil vapors from the back of the valve cover and "separate" the oil to only send the fumes to the intake, while the accumulated oil goes back into the crankcase?
When the unit is defective, can we presume it sends the fumes and oil through the intake and burn the oil?

Thanks for your help again!

pcy

The way engine is designed, you won't see whole lot of vacuum/pressure when you open the oil filler cap. That's the reason why they have a separate vacuum pump to provide necessary vacuum.

Your description of oil separator's function is accurate. If the oil separator is not functioning the way it was designed or blocked, you will see oil in the intake and that gets burned ... as a result, oil consumption goes up.