oil/gunk in intake manifold e36 328i - United Bimmer Community

**mavricbmw** · 12-19-2010, 03:34 PM

Hi guys, any help with this matter will be greatly appreciated.
My e36 328i 1996, started smoking heavily, white smoke, on startup, i stripped the whole intake system to find it was so greasy and grimy. i cleaned the ICV and another component that looks like it has something to do with a vacuum block, i think to stop oil vapours from the sump getting into the intake. After cleaning the intake side and put eveything back together my car stopped smoking which was awsome however as time has gone by it has started smoking and is now very bad and using oil, i susspect i need to change this component and the other component aswell. any sugestions or advice?? thanks so much

**Manolito** · 12-20-2010, 09:58 AM

The fear is that you have excessive blowby past your rings, causing the crankcase to pressurize and push a lot of oil mist out the vent from the valve cover to the air intake tube. The hope, on the other hand, is that your PVC is not evacuating the crankcase as is should.

Did you clean your PVC valve and make sure the hose from the PVC down to the oil pan is clear? The PVC is beneath the throttle body. It is shaped surprisingly like a human heart.

There is a hose from the cyclone separator at the bottom of the PVC down to the oil pan. That hose swells up and turns to mush over time. It is an odd size, but a well stocked auto parts store will carry hydraulic hose with that inside diameter in bulk. Just have them cut a piece to fit. My BMW dealer does not stock that hose as a part because hydraulic hose is cheaper and better.

I broke my PVC trying to open it up to clean it so I had to buy a new one. Not cheap. I think it was around $175. Next time I would just flush it out well with solvent without trying to open it up.

**mavricbmw** · 12-21-2010, 02:01 AM

Hey Manolito, thanks for the reply, i suspect you are right, the car has alot of km's on the clock, surely if i have blowpast the rings it would smoke all the time, cause as soon as i've cleaned everything it on the intake side, it doesnt smoke, even if i rev it up, i'm next to certain now it must be that pvc device that isnt funtioning properly, i also tried to open it but stopped when i saw it was going to break if i forced it, seems like bmw manufactures them that way, once its clicked together it wont come apart. any idea whats inside the pcv that makes it work? someone told me that i should just blank it off, not sure what he means though, i dont feel thats wise any suggestions?

thanks chris

**Manolito** · 12-22-2010, 09:54 PM

You are correct to be hesitant to blank it off. A certain amount of blowby is normal, even in a new engine, and that blowby has a a lot of water vapor in it. The PVC keeps the water vapor swept out of your crankcase so it does not mix with your oil and cause foam and sludge.

The gas coming from the crankcase always has oil droplets suspended in it. The PVC has a cyclone separator in it so the oil droplets drain down to the oil pan and the rest of the blowby goes into the intake manifold behind the throttle.

Ideally, the PVC pulls a slight vacuum in the crankcase, pulling fresh filtered air from the air tube upstream of the throttle valve through a vent hose to the crankcase. This fresh air replaces the damp air and blowby that the PVC is drawing out. The oil droplets are separated in the PVC, and the remaining blowby air and water vapor goes to the intake manifold downstream of the throttle valve. If the PVC is not working, or there is excessive blowby, the crankcase pressurizes and the blowby comes out of the vent that is supposed to carry fresh filtered air in. The oil droplets in that blowby gunk up the intake tube and throttle body and idle air control and cause all kinds of grief.

If the car has several hundred thousand km on it, there will be so much blowby at high RPM that it will come backwards up the vent tube and gunk up the throttle body and idle air control valve a bit. This is normal for older cars (I know all about older cars, I have several). That is why you can drive a car the first 10 years without ever cleaning the throttle body, but by the time the car is 20 years old, you have to clean the throttle body at least once a year.