CCV and oil pressure pondering

[JCL]

To build on what twinspoppa posted, CCV refers to the crankcase ventilation system. The system includes vent lines from the valve cover, and performs the same function as a positive crankcase ventilation (PCV) valve. There is actually a valve in there, as it allows pressure to be released to the intake, while not flowing the other way at times of high manifold vacuum. BMW added an oil separator in to the system, to remove engine oil mist from the ventilation system. That is cleaner, environmentally, than burning the oil mist in the engine. The oil that is removed from the vented air flow is then returned to the oil sump. It is a fairly elegant system, except that in some models the separator is not mounted close enough to the engine to be kept warm, and it can freeze up.

There is usually condensation inside the engine due to heating/cooling cycles, but in the normal course of events it is boiled off when you drive. If the engine does not get hot enough, for a long enough period of time, that condensation will build up and eventually form an emulsified paste that collects under the valve cover. If enough of it builds up, it can collect in the crankcase ventilation system. That would still not be a huge problem, except that it has water in it, and so it can freeze if it gets cold enough out. If the valve in the CCV freezes in the closed position, then you no longer have a functioning crankcase vent, and crankcase pressure can build up. What will happen is that the pressure will push out past the weakest gasket, usually the valve cover gasket. On the other hand, if the valve freezes in the open position, then during times of high manifold vacuum oil from the sump can be drawn up into the intake manifold, potentially leading to a hydraulic lock if the oil makes it into a cylinder. That isn't common, but if it does happen, it can be catastrophic.

So, this is not related to the oiling system (except that separated oil is returned to the sump).

I don't know how similar the 4.6 is to the 4.4, and it varies slightly from year to year as well, but the principles are the same.

[taosx5]

Originally Posted by JCL

To build on what twinspoppa posted, CCV refers to the crankcase ventilation system. The system includes vent lines from the valve cover, and performs the same function as a positive crankcase ventilation (PCV) valve. There is actually a valve in there, as it allows pressure to be released to the intake, while not flowing the other way at times of high manifold vacuum. BMW added an oil separator in to the system, to remove engine oil mist from the ventilation system. That is cleaner, environmentally, than burning the oil mist in the engine. The oil that is removed from the vented air flow is then returned to the oil sump. It is a fairly elegant system, except that in some models the separator is not mounted close enough to the engine to be kept warm, and it can freeze up.

There is usually condensation inside the engine due to heating/cooling cycles, but in the normal course of events it is boiled off when you drive. If the engine does not get hot enough, for a long enough period of time, that condensation will build up and eventually form an emulsified paste that collects under the valve cover. If enough of it builds up, it can collect in the crankcase ventilation system. That would still not be a huge problem, except that it has water in it, and so it can freeze if it gets cold enough out. If the valve in the CCV freezes in the closed position, then you no longer have a functioning crankcase vent, and crankcase pressure can build up. What will happen is that the pressure will push out past the weakest gasket, usually the valve cover gasket. On the other hand, if the valve freezes in the open position, then during times of high manifold vacuum oil from the sump can be drawn up into the intake manifold, potentially leading to a hydraulic lock if the oil makes it into a cylinder. That isn't common, but if it does happen, it can be catastrophic.

So, this is not related to the oiling system (except that separated oil is returned to the sump).

I don't know how similar the 4.6 is to the 4.4, and it varies slightly from year to year as well, but the principles are the same.

Thanks JCL, I sort of understood the concept but this really helps. I guees in other threads I read and pictures I had seen it must have been the older valve you mentioned because it was flat and came apart in two pieces displaying a rubber gasket that could be replaced. I wil do more reading and see if there is anyone with a similar problem on the 4.6. In my case the oil is definitely coming from the top of the oil filter cannister. I suspect that is the weakest link you describe. I appreciate your help.

I am on a road trip right now in the wife's 4.4 dealing with a mystery head lamp issue that I described in another thread. Thanks again.

[JCL]

The oil filter canister is pressurized with oil, so that isn't the same as the crankcase vent. Make sure that it is actually coming from there, and hasn't just dripped down. If it is coming from the canister, replace the seal.

[taosx5]

Originally Posted by JCL

The oil filter canister is pressurized with oil, so that isn't the same as the crankcase vent. Make sure that it is actually coming from there, and hasn't just dripped down. If it is coming from the canister, replace the seal.

JCL here is what has happended with me. Two times in the last three weeks, it has leaked oil then stopped. Both times were consistent with the very cold temps (around 0 farenheit) outside maybe around 40 degrees inside the garage. There was snow on the ground so I did not have the X5 out for a couple of days prior to these cold starts. It was in the garage. It leaked upon start up then after things warmed up and was restarted the leaking stopped. Both times it was leaking from around the top of the oil filter cannister, then stopped. It has never leaked from there before. And I last changed the filter and large rubber O-ring about 6,000 miles ago. I always changed filter when I change oil. I checked to make sure the lid was tight and not over tight. I always hand tighten it then with water pump pliers tighten it another quarter to half turn. I just changed the oil and filter a couple of days ago and after initial start up there was no leaking that I could find. The two times it leaked before it left a visible pool of oil right below the oil filter.

My theory is that there is too much pressure in the oil delivery system maybe caused by some gunk in the OS and as you mentioned blows oil out the weakest link. If it is causing it to blow it out the oil filter, to me that is better than blowing out a valve cover gasket. Is this rational thinking?

[JCL]

No. The valve cover gasket is not under pressure (inside it is just oil draining down). It isn't the oil which blows out the gasket, it is the air pressure. That is nothing to do with high oil pressure, those are two entirely different circuits.

But I don't believe you have high oil pressure. Much more likely that it is a problem with the seal on the oil filter cannister. Do not tighten it with water pump pliers. Use a torque wrench and tighten it properly. And change it every time you change the filter. It doesn't take much torque at all, and too much will just damage the O-ring.

[taosx5]

Originally Posted by JCL

No. The valve cover gasket is not under pressure (inside it is just oil draining down). It isn't the oil which blows out the gasket, it is the air pressure. That is nothing to do with high oil pressure, those are two entirely different circuits.

But I don't believe you have high oil pressure. Much more likely that it is a problem with the seal on the oil filter cannister. Do not tighten it with water pump pliers. Use a torque wrench and tighten it properly. And change it every time you change the filter. It doesn't take much torque at all, and too much will just damage the O-ring.

Thanks JCL, do you know how want the torque setting is for the oil filter? I don't have a torque wrench so will need to get one. And I do change the seal every time I change the filter.

On another note, I did take the X5 to a Indy shop to have the OS and lines replaced. I was also experincing a small coolant leak which was evident by a burning coolant smell upon start up then go away and a small amounts of coolant residue on the skid plate. I suspected the valley pan gasket and that was confirmed yesterday. Since much of the labor would be repeated to address both issues I decided to have the OS replaced, the valve cover gaskets (which showed a little seepage), the valley pan gasket, the water pump, all coolant and vacuum hoses.

Would you recommend any other things at this time?

I was also experiencing a small steering wheel vibration upon breaking at speeds above 60 mph. It was not an issue and I suspected that the bushings on the control arms might be the culprit or possible the rotors, (after market slotted/drilled rotors). They checked the bushings which were fine. They said the front rotors are slightly warped and are checking to see if they can be turned.

Thanks

[JCL]

Mine was 25 Nm, for the drain plug and oil filter cap. If it is a V8 with a drain in the filter cover, I believe that is 10 Nm. In any case, I would check your filter cap for a torque spec, though.

Side note, but rotors don't usually warp, shops and others just call if warping. You get a deposition of pad material on the rotor as a matter of course, and if it is uneven, it produces a pulsing in the pedal. It can be very slight, but if there is any looseness in the suspension it will be enough to start the shaking. Turning the rotors gives you a new clean friction surface (if there is sufficient material there to turn them) but if the pads deposited unevenly on those rotors the first time there is nothing changing that would stop them doing it again. It is the combination of the pad characteristics, the surface finish on the rotors (modified by the drilling and slotting), and your driving habits. Just expect it to happen again.