[lvb125]

I d like to sort out my oil consumption with my N52. I am wondering about PCV valve. What is the way to diagnose it? There seems quite a lot of PCV talk with N54 engines but not with N52s. Thanks!

[lvb125]

It is worth mentioning that mine is an 06 with serviceable oil/air seperator and I d like to know what it takes to have this PCV system overhauled.

[Tim603]

Ive been wondering about this as well, its a very common maintenance item on alot of other cars but dont really hear much about it on N52. Maybe its something that we dont need to worry about?

[GoRomeo]

Originally Posted by lvb125

I d like to sort out my oil consumption with my N52. I am wondering about PCV valve. What is the way to diagnose it? There seems quite a lot of PCV talk with N54 engines but not with N52s. Thanks!

Do you have any leaks? Mine has a bad leak and still takes about about to 10 months before I need to add oil. By this time its time for an oil change anyways so I just change the oil.

[lvb125]

Originally Posted by GoRomeo

Do you have any leaks? Mine has a bad leak and still takes about about to 10 months before I need to add oil. By this time its time for an oil change anyways so I just change the oil.

Only visible VCG leak and VT gasket leak. The car had only done 5500km (3500 miles) since the last service at dealer and the digital dipstick is at the last 1/4 notch for a while now, probably will ask me to top up very soon. Looks like it is losing more oil than those leaks.

[MD64]

Hey lvb125! I have a Canadian 07 323i (N52B25l
) that is consuming about 1L of oil every ~2000km. I also suspect the PCV system, as I get a bit of vacuum at the oil fill cap, and a gurgling sound from the engine with the cap off. Did you service the PCV system on your car?

[Three_thirty_I]

I am also keen to know what other N52 engines do when opening the oil filler cap, what is correct and what points to a problem etc. Took a vid earlier this year of this, so I decided to upload and post here to see what you guys say.

[matteblue3er]

Originally Posted by Three_thirty_I

I am also keen to know what other N52 engines do when opening the oil filler cap, what is correct and what points to a problem etc. Took a vid earlier this year of this, so I decided to upload and post here to see what you guys say.

This sounds completely normal.

Typically, the PCV hoses going along the back of the valve cover to the oil separator and from the oil separator back down to the oil sump are what break and leak.

Over time the plastic becomes very brittle from heat exposure and they break apart. It's hard to see the leaks because these hoses are wrapped in foam insulation. The oil soaks the foam and doesn't drip until the foam is completely saturated. There is also a heating element wrapped around the hose to pre-heat it.

Squeeze the foam and if oil seeps out, the hose is broken.

There is also a mesh screen inside the valve cover that can clog and/or collapse. BMW does not sell this screen separately and you are suppose to replace the valve cover. However this company sells just the screen. There is a test method described in that link and also a guide on how to replace the screen. http://vanos-bmw.com/membrane-for-co...mw-11127552281

When this screen clogs or collapses, it typically makes a very high pitched noise.

[lichtgelb]

You can check the CCV diaphragm by disconnecting the small vacuum hose that runs over the intake to the throttle body. Disconnect the hose at the throttle body, with the engine off, and see if you can pull vacuum. If you cannot the diaphragm has failed. If the diaphragm has failed it will not close off at idle and expose the crank case to full manifold vacuum. That can increase oil consumption through the intake.

I changed my entire CCV on my N52. My diaphragm was broken and the cyclone inside the oil separator was clogged so oil was going directly into the intake.

[Three_thirty_I]

Thanks guys, this is good information, learnt a few things that I wasn't sure or aware of. Yep, those vent hoses are heated, and worryingly I suspect have been the cause for a few freak N52 engine fires when for whatever reason they short out.

[MD64]

Do you guys know if the N52B25 (323i) has a serviceable oil separator, or if it is built into the valve cover? Got reference, I have a black plastic engine cover rather than a magnesium one.

[lvb125]

Originally Posted by MD64

Do you guys know if the N52B25 (323i) has a serviceable oil separator, or if it is built into the valve cover? Got reference, I have a black plastic engine cover rather than a magnesium one.

Which year is it? most likely it is built into the valve cover. Check realoem.com for your vin to make sure. my oil separator part number 11617531423 is applicable to some early na 323i cars, but they also has the same valve cover part number as my 330i.

[fravel]

Planning to tackle a full CCV system replacement this weekend as my car has been presenting with 2A2E and 2A2F ('fuel mixture control') for a few weeks now. Tried cleaning MAF, put in new plugs and coils as well as new VANOS solenoids all to no effect.

Further forum research has indicated that a fubar CCV system can cause these codes, and I remember my mechanic bitching about the hose that goes to the oil pan when he changed my oil pan gasket, so I suspect that hose is broken. I'll report back with any unusual findings or if I discover any useful tips.

[Sandose]

Just to also point out BMW has released a STB on the oil consumption question a while ago. They say the maximum acceptable consumption rate for oil is 0.7L/1000KM. Also depends on driving style. I can post the bulletin if you guys want to read it.

[Three_thirty_I]

That's pretty much about the standard tolerance that most manufacturers use as a guideline. In fact, I've heard typically 1l/1000km is considered the limit.

[fravel]

Originally Posted by fravel

Planning to tackle a full CCV system replacement this weekend as my car has been presenting with 2A2E and 2A2F ('fuel mixture control') for a few weeks now. Tried cleaning MAF, put in new plugs and coils as well as new VANOS solenoids all to no effect.

Further forum research has indicated that a fubar CCV system can cause these codes, and I remember my mechanic bitching about the hose that goes to the oil pan when he changed my oil pan gasket, so I suspect that hose is broken. I'll report back with any unusual findings or if I discover any useful tips.

Finished this job this past week here's my thoughts:

#1. All the DIY's I've read instruct you to slide the wiring junction box off of the bracket at the bottom of the intake manifold - as far as I can tell this is impossible to do without breaking the tabs on the wiring junction box. The easy way to do this is to actually remove the bracket from the intake manifold, it's just 2 T27 torx screws. Unfortunately I managed to strip one of those screws so I had no choice but to break the tabs on the junction box. When I reassembled I just clamped it back in place with a zip tie.

#2. Assuming you are replacing your entire PCV system, don't bother with trying to disconnect the various hoses, just grab ahold of them with your hand and break them. They are very brittle and it takes no effort. After you've got the manifold out of the engine bay you'll have plenty of room to work and get to the portions of the hoses that stayed attached to the car.

#3. I also have no idea how anyone manages to disconnect the power wire that is running to the electrical distribution block on the back of the intake manifold, I ended up having to cut that wire and then splicing it back together after the manifold was out of the car.

I didn't actually tear down the old PCV to inspect it, but my intake manifold was full of oil so I strongly believe it was failed. If you have a 3-stage manifold, I recommend pulling the DISA valves out and inspecting them. Turns out my outer DISA had failed and the flap was no longer attached to the shaft - I believe this was the actual culprit of my check engine light.

My inner DISA was still tight but I noticed that the seals on it were badly degraded from all the oil in the manifold. I went ahead and replaced it as well since I already had the intake manifold off.

[Three_thirty_I]

It's a few years on, so my memory is a bit rusty, but having taken the intake off my 330i to replace the DISA units myself I know what you mean! I could not get the one cable harness or pipe that was attached to the cable clamp on the intake manifold close to the engine bay firewall. And then that junction box for the vent hose plugs was another tricky part. With the limited space and not wanting to break things, I called it a night since I had to get the second DISA unit from the dealer the next day anyway, so popped into their workshop and asked one of their mechs. Told me to remove the metal bracket that holds that junction box onto the intake manifold as well as the metal bracket that holds the cable clamp onto the intake manifold. Once those were off, it was plain sailing!

[andas]

Originally Posted by lichtgelb

You can check the CCV diaphragm by disconnecting the small vacuum hose that runs over the intake to the throttle body. Disconnect the hose at the throttle body, with the engine off, and see if you can pull vacuum. If you cannot the diaphragm has failed. If the diaphragm has failed it will not close off at idle and expose the crank case to full manifold vacuum. That can increase oil consumption through the intake.

I changed my entire CCV on my N52. My diaphragm was broken and the cyclone inside the oil separator was clogged so oil was going directly into the intake.

Do you mean this hose?


I think for some reason I don't have it... And what do you mean pull vacuum?

[PhaseP]

Only very early N52's have that tiny hose that goes from CCV to the intake entry hose. Later years removed that hose, and the section where it attaches to the CCV has been made to be open to atmosphere. It is a small nipple on the top of the CCV. It has a "dust" cover on it, which may have fallen out and lost if played with before. You can pull that dust cover, and put a tube at the nipple. Then gently blow in some air, you should be able to blow in air for a second or so an then it should stop, no more air can be blown it. If you can keep blowing in air, it means the membrane inside the CCV got cracked and letting air pressure in from there into intake. That is one failure mode of the CCV.
The other failure mode is, the valve surface inside that is in the middle of the membrane gets dirty and hard. Then it cannot seal well to balance the vacuum that will go into crankcase. This you cannot test from outside. One way is to open and check the intake manifold, if it is filled with too much oil or not, if it is it means the CCV is not working as supposed to.
Other failure mode could be humidity and oil mixture building up on the CCV hoses and blocking them. Other failure is cracked hoses, not common unless intake was worked on it.

More info:

http://www.e90post.com/forums/showthread.php?t=1312867

[Nebraska330xi]

I just did this full replacement. Is weekend and yes although realoem called out that part, my throttle body didn't have a place for it and it wasn't present on my car before. So I'll return it. Seems like an old thread here but if anyone is doing this and have questions let me know. I'm finding the 2006 resources to be a bit fuzzy since a bit changed going to the 328

[andas]

Originally Posted by PhaseP

Only very early N52's have that tiny hose that goes from CCV to the intake entry hose. Later years removed that hose, and the section where it attaches to the CCV has been made to be open to atmosphere. It is a small nipple on the top of the CCV. It has a "dust" cover on it, which may have fallen out and lost if played with before. You can pull that dust cover, and put a tube at the nipple. Then gently blow in some air, you should be able to blow in air for a second or so an then it should stop, no more air can be blown it. If you can keep blowing in air, it means the membrane inside the CCV got cracked and letting air pressure in from there into intake. That is one failure mode of the CCV.
The other failure mode is, the valve surface inside that is in the middle of the membrane gets dirty and hard. Then it cannot seal well to balance the vacuum that will go into crankcase. This you cannot test from outside. One way is to open and check the intake manifold, if it is filled with too much oil or not, if it is it means the CCV is not working as supposed to.
Other failure mode could be humidity and oil mixture building up on the CCV hoses and blocking them. Other failure is cracked hoses, not common unless intake was worked on it.

More info:

http://www.e90post.com/forums/showthread.php?t=1312867

Do the ccv hose electrical connectors have anything to do with propper ccv function? I saw couple of them disconnected ( from the place on intake manifold where 4 connectors can be plugged in only 2 were plugged in on mine)

After researching on internet I saw that my power connector for ccv that comes from junction box under intake and valve cover hose electrical connector wete not connected.

I will remove to check if oil is in manifold, because other time when someone else did this for me there was a lot of oil.
And is it 100% that the diaphragm fails is oil is in manifold? I will try to look somewhere to blow to test if I can find it. Maybe in my case I just need to plug in the power connectors?

[PhaseP]

Do the ccv hose electrical connectors have anything to do with propper ccv function?

Electrical connectors are for heater elements heating the hoses and the CCV.

Google "BMV CCV Mayo" you will have more information on this. Previous to E90 these hoses and CCV didn't have electrical heaters as far as I know, and caused lots of problems.

One link http://forum.e46fanatics.com/showthread.php?t=1185209

The air from crankcase contains fine mist of by products of gas burning (that made past the piston rings), oil and moisture. When oil and moisture mixed up condenses due to cold, it becomes a milky mayonnaise looking substance. This eventually clogs up the CCV or the hoses. In extreme cases I have read it is reported it can even cause the hoses or CCV's to crack when water content freezes and expands.

With the heat from the electrical heaters moisture evaporates and the milky mayo gets loosened up if formed and flows as it should.

One important hose is the return hose that goes from under the CCV to the oil pan. If this is clogged oil won't be able to return back to the oil pan, then the it goes to intake manifold. This return hose also in E90's have a built in check valve at the elbow that connects to the oil pan. Again from what I read in previous to E90, they didn't have this check valve. Probably because this return hose was becoming the oil dip stick tube also in those models.

This check valve is very important for preventing catastrophic failure in case the CCV malfunctions and applies full vacuum to crankcase. Without it in such case oil will be sucked out from the oil pan into the intake continuously, ending in engine loss after enough oil is sucked and burned or probably hydro lock. On E90 because there is no dip stick, they were able to place a check valve (ball operated) on the end of that tube connecting to the oil pan. It seems to have been working because there are no horror stories of loosing an engine like that for E90.

What I am coming at is, if you were to replace or service the CCV, I highly recommend replacing this hose to get a brand new operating check valve. It will very likely get cracked during removal anyway. At the least clean it, but with something that doesn't attack plastic. If you remove that hose, you can check if the check valve is operating by blowing it from either side: from oil pan side it shouldn't allow you to blow, from other side it should. Also when you shake the hose freely you should hear the ball at the end of it rattling freely.

And is it 100% that the diaphragm fails is oil is in manifold?

No, the diaphragm may be fine but the hoses got clogged.

And diaphragm can fail in two ways: either by getting raptured, or by getting dirty and hard. In former, you will have vacuum leak, most likely will have codes related to it and idle problems. In later you will have oil in intake, you may have too much vacuum applied to crankcase at idle. Even you may hear squealing noise from crankshaft seals because vacuum pulls air from them into the engine. Opening the engine oil fill cap will be difficult with too much vacuum at crankcase.

The heater elements and return oil hose is for metal (magnesium) valve cover E90's that come with silver engine vanity covers. The other later year E90's have plastic valve covers which have the CCV integrated into the valve cover. Which does away with heater elements because engine heats up the cover, and also with the complexities of the oil return line because now the oil returns to oil pan inside the engine. The diaphrapm still can crack, and get dirty and what not though.