Oily intake manifold - could it be anything but PCV?

F

Fabiantir

Member
Hi all,

Had a long weekend so took the opportunity to do some Z4 surgery - OFH and oil cooler gaskets done (very overdue, area underneath was disgusting), mickey mouse hose replaced (it broke when removed, obviously), new PCV pipe installed, 2 DISA valves replaced.

All put back and done up tight - smoked intake downstream of throttle body, and then everything downstream of MAF and all good. No leaks anywhere, fuel trims look ok.

However I still have the slightly rough idle that has been present ever since I bought the car, it gets cat efficiency codes now and then, and I discovered oil in the intake when doing all of the aforementioned work.

I had wondered if the rough idle was due to old vanos solenoids as there's no record of them being replaced and the car is at 166k miles, but the oily intake makes me wonder if the PCV thingy on the valve cover has failed instead.

Before I set about getting a new membrane kit, is there literally any other reason that my intake manifold would be full of oil?

Car is a 2006 E86, 166k miles, plastic valve cover N52.

Thanks a lot in advance!
 
Didn't see any responses,

But besides DISA, I can't see how else oil would get into the intake besides if the CCV was failing. If you replace your plastic valve cover, also replace the Eccentric Shaft Sensor (it's at the front of engine but under the valve cover), that will definitely make a difference on the rough idle front. VDO makes the sensor and it's a lot cheaper than BMW-branded one.

I also suggest using BMW OE gaskets for valvetronic motor, and the valve cover, etc. I hear the Rein or other "OE" gasket brands end up with small leaks on valvetronic which also cause rough idle.

I'd definitely suggest replacing or cleaning the VANOS solenoids and the solenoid check valves.
 
r3vmatch said:
Didn't see any responses,

But besides DISA, I can't see how else oil would get into the intake besides if the CCV was failing. If you replace your plastic valve cover, also replace the Eccentric Shaft Sensor (it's at the front of engine but under the valve cover), that will definitely make a difference on the rough idle front. VDO makes the sensor and it's a lot cheaper than BMW-branded one.

I also suggest using BMW OE gaskets for valvetronic motor, and the valve cover, etc. I hear the Rein or other "OE" gasket brands end up with small leaks on valvetronic which also cause rough idle.

I'd definitely suggest replacing or cleaning the VANOS solenoids and the solenoid check valves.
Click to expand...
Thanks - I am also 99% sure it will be the PCV, I just don't see how else oil could get there. Just wanted to make sure I'd covered all bases.
 
I agree with R3vmatch that the CCV /PCV valve is your likely oil source, and with the suggestion to replace the Eccentric Shaft Sensor (ESS) while you are removing / replacing the valve cover (VC). The new seal for the ESS installs from the INSIDE of the valve cover, so it's worth doing while the VC is off.

It's interesting to see your 2006 E86 car has the "Black Top" plastic valve cover. At least you don't have to replace aluminum screws with every VC removal / replacement.
 
Z4Mariner said:
I agree with R3vmatch that the CCV /PCV valve is your likely oil source, and with the suggestion to replace the Eccentric Shaft Sensor (ESS) while you are removing / replacing the valve cover (VC). The new seal for the ESS installs from the INSIDE of the valve cover, so it's worth doing while the VC is off.

It's interesting to see your 2006 E86 car has the "Black Top" plastic valve cover. At least you don't have to replace aluminum screws with every VC removal / replacement.
Click to expand...
'Twas built in December of '06 so presumably right around the switch to black tops. Handy about the VC indeed - annoying though cos the gasket was done w/ timing chain at 110k miles and it's currently solid and not leaking. Don't particularly like the idea of poking stuff that's not leaking but I might not have a choice lol
 
Before you go spending too much time and effort, think about whether it is simply normal. I changed the manifold on my N52 2.5i (upgrading to double DISA) and there was a fair amount of oil in it. I helped another member do exactly the same job and there was oil in his too. Both cars were running perfectly and didn’t have a noticeable oil consumption. These are sub-100k milers and I’m talking about maybe a quarter pint. If you have this much, or more due to the higher mileage, it’s probably to be expected.
 
Thanks - considering there are no leaks from the valve cover, no vacuum leaks, and no obvious oil consumption, maybe it's just the way it is as you say.
Zedebee said:
Before you go spending too much time and effort, think about whether it is simply normal. I changed the manifold on my N52 2.5i (upgrading to double DISA) and there was a fair amount of oil in it. I helped another member do exactly the same job and there was oil in his too. Both cars were running perfectly and didn’t have a noticeable oil consumption. These are sub-100k milers and I’m talking about maybe a quarter pint. If you have this much, or more due to the higher mileage, it’s probably to be expected.
Click to expand...
 
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