[Efthreeoh]

Looking for advice on replacing the oil separator. I'm thinking it is the cause of high oil consumption. Anyone have any experience with it?

Thanks.

[thomas88162]

It is integrated into the valve cover; you would have to replace the entire thing. They are known to fail, but the part has been updated since the originals. A common sign of failure would be whistling or excessive vacuum upon opening the oil filler cap.

Its not on a 325i/330i, I've replaced mine once.

[thomas88162]

Originally Posted by index1489

Its not on a 325i/330i, I've replaced mine once.

It's not on a 2006 model, yes. After that they are all integrated into the valve cover.

[Efthreeoh]

Originally Posted by Broken_Gearbox

Mine is on its way out. Every 2500-3000 miles I get through a liter of oil. I have had worse before on other cars. Changing the oil every 3000-4000 miles can help prolong its life in some cases. I'm dragging it out until next year.

What model/engine is yours? How much are you burning?

The engine is a 2006 N52. The issue is I'm now at 263K. I've got a weeping oil pan gasket and a weeping rear crank seal, which is contributing, but keeping track of it by noting mileage of the 1/4-increments in the e-dipstick, the engine was using about a quart every 5,000 - 7,000 miles. However the last two weeks the e-dipstick showed a 1/4 qt. drop in 600 miles, then an other 1/4 quart drop in just another 300 mles after that from full (I just added the a quart). Once E90 reaches 186,000 miles the CBS is programmed to stop receiving and using data from the oil quality/level sensor. Ever since abut 221,000 miles (the last oil change when the CBS would only reset to zero) the e-dipstick has been behaving totally different than before the oil life monitor goes defunct. The engine is in good shape otherwise, power is good, fuel mileage is on track, the exhaust tips are dry but a little black (normal) and there is no oil residue on the back of the car. The cats are still good too. I had it in the dealer yesterday for an eval. The tech indicated it could be the oil separator is over pressuring and causing the abnormal oil consumption.

Thought I'd see if anyone else had a similar experience.

Thanks for the reply.

Try opening the oil filler cap while the car is running there should be a very light amount of suction not too much not too little, there is a special tool that will measure exact and can be compared to BMW specs, but in general if you have access to another E90 to compare it should work just by feel.

If you do replace the oil separator, make sure to order all the hoses, the one that runs from the valve cover to oil separator, the one that runs from oil separator to intake manifold and the one that runs from oil separator to oil pan (drain).

At that miles they are going to be so brittle I guarantee you will break them during the removal.

Have you had the intake manifold off before on a 2006 N52? I've done it twice once to replace starter and once to replace separator, the hardest part is the routing of all the cabling, make sure you get it right.

Plus all those hoses are heated and have heating wires that plug into the very back of the manifold, and they have those stupid connectors where you need to pry the flap up to remove the connector, they can't be removed one handed.

[Efthreeoh]

Originally Posted by Broken_Gearbox

It sounds like you have a lot of negative pressure in the crank case. When the ccv/oil seperator fails the pressure can cause gaskets and seals to fail. Do you make a lot of short jorneys? Its a good idea to take a longer drive once a week if you can to burn off any moisture in the system. As above a good test is to loosen the oil cap and see if it gets sucked in. Replace ASAP to be safe with all associated pipe work.

LOL. Laughing because it's quite the opposite; I drive 160 miles a day, 80 miles one way. I'll perform the oil cap test, but any engine is under vacuum, so I'm not sure what that will tell me.

[Efthreeoh]

Thanks for the inputs everyone.