Crankcase ventilation system

[Dark5yde]

Originally Posted by Dark5yde

Yesterday dropped the X off at the dealer I bought it from to do a cooling system pressure test as well as cylinder checks. My coolant is going somewhere....my oil is a bit milky....My guess is head gasket or cracked head. I've never let the thing overheat or anything. They are hoping its the CV system kicking back moisture into the oil.

Well after the pressure test on the coolant system there was no leak. Same goes for the cylinder test. Did and oil change and the oil actually looked really good, not milky. He did the remove the oil cap while running test and the idle did not change. So his thought is that the CV system is plugged or blocked and that is causing the white residue on the cap and dipstick. My question is this, all I found on ECS is a tube that goes from the cover to the oil separator. I doubt that is my issue unless it is plugged solid. Could the separator (crankcase pressure regulator valve) be bad? I'm assuming its the CPRV should be changed as he said I would need to do a valve cover gasket along with it if I tackled it myself. Just looking for a bit of insight.

[raider03]

Well I am not sure why you would need to change the valve cover gasket? Maybe he meant the intake manifold gasket, as the CCV system is underneath the intake manifold...

But you don't really need to take off the intake manifold, its just easier to do with the intake manifold off. I have never done the CCV system but I heard it is a lengthy job to tackle, about 8hrs of labor or so.

BTW the CCV system is all parts that you see on the diagram except for the valve cover.

[raider03]

Originally Posted by Dark5yde

He did the remove the oil cap while running test and the idle did not change.

Another thought if your ccv was bad then there would have been problems with idle and strong suction when he took off the cap with the engine running.

Here is some more info on diagnosing the CCV system...
How to test the BMW E39 pressure-controlled crankcase ventilation system (CCV)? - Bimmerfest - BMW Forums

[Dark5yde]

Originally Posted by raider03

Another thought if your ccv was bad then there would have been problems with idle and strong suction when he took off the cap with the engine running.

Here is some more info on diagnosing the CCV system...
How to test the BMW E39 pressure-controlled crankcase ventilation system (CCV)? - Bimmerfest - BMW Forums

That is opposite of everything I have read. If the CCV system was working and supplying the 10-15psi vacuum in the engine then when you take the cap off it would mess up the idle and sometimes toss a code because you would have essentially created a vacuum leak. However if the system was plugged and not working there would be no visible effect in the idle due to the vacuum not being there as it should be.

Either way I think I am on the right track with wanting to replace all the parts of the CCV system and being done with it.

[epdarks]

I just had a CCV failure as well. Based on what you've posted... I do think you're on the right track. Replace all components and hoses/clamps if necessary. After replacement, consider an oil change and then do a nice long drive to get oil up to temp and oil running through the new CCV.

[JCL]

Originally Posted by Dark5yde

Well after the pressure test on the coolant system there was no leak. Same goes for the cylinder test. Did and oil change and the oil actually looked really good, not milky. He did the remove the oil cap while running test and the idle did not change. So his thought is that the CV system is plugged or blocked and that is causing the white residue on the cap and dipstick.

The thought process here is incorrect, as the cause and the effect are being confused.

A plugged crankcase ventilation system does not cause moisture in the oil. It is the other way around. Moisture in the crankcase (naturally occuring condensation from heating/cooling cycles) mixes with the oil and leads to a build up of condensate (a white paste) and that can collect in the crankcase ventilation system, causing subsequent problems.

Neither of the above causes a loss of coolant, which is what you reported you were experiencing.

While the buildup of moisture is largely from condensation, you could have a coolant leak contributing to it, but that has not been determined yet.

The paste is usually at the top of the engine, under the fill cap. It can also collect in the CCV system. That isn't usually a problem until it gets cold enough out to freeze it. The paste can clog the CCV, but the usual failure mode is when it freezes (it freezes because it has water in it). When it freezes, the CCV can be stuck in one of two positions. If it is stuck closed (or blocked by the paste) then the engine crankcase becomes pressurized, and eventually blows out through the weakest point, often a valve cover gasket. If it is stuck open, then high vacuum from the crankcase (which happens on throttle over run, ie lifting your foot at medium to high rpm) can draw oil from the sump, through the CCV, and into the intake stream. That isn't a vacuum leak, it is a vacuum powered siphon.

If any of the vacuum hoses are shot, then you can have a vacuum leak.

When you think about vacuum, you need to separate the different zones inside the engine. The engine crankcase does not normally have a vacuum, it is close to zero pressure differential. The oil filler cap leads to the crankcase. A separate zone is the intake system, from the air filter through to the intake valve to the combustion chamber. That is where there is vacuum. You can't access that system through the oil filler cap.

[Dark5yde]

Wow..awesome post thank you! As for the coolant we did notice the tiniest of pinholes in the neck of the res. Hardly even noticeable. I suppose under full pressure over a cpl days or so the coolant can drop enough to trip the sensor. But besides that again it seems all signs point to something in the CCV system. All the signs are there on our end as well. Very cold winter..short drive times.. I could probably pop one of the hoses off and have a look inside. But I know the white junk came from somewhere. Also noticed today I took the oil cap off and there is already condensation under it. Not white just alot of drops.

[JCL]

Again, all the signs do not point to the CV system. They point to the short drives, with the engine not getting up to full operating temperature and being kept at that temperature long enough to boil off the condensation. Condensation is natural, as the engine is going through cold/warm cycles several times per day. The condensation from the air collects at the top of the engine. That is where the white paste is coming from.

If you do one or more hot oil changes in quick succession, you will clean the engine out somewhat. That won't in any way clean out the CCV system, as the oil doesn't circulate there, but it will clean out under the valve cover. You should also make a point of getting it good and hot, drive it for an hour or so. Ideally, you should be doing that once per week.

The CV system can be plugged up by the white condensate paste, but it in no way contributes to it. Problems with the CCV are a downstream effect, not an upstream cause.

[Dark5yde]

ahhh ok I gotcha now. I appreciate the descriptions man.