How you check PCV system on a 750 V12

[shogun]

Here is how you check PCV system on a 750 V12

1. Start the engine.

2. Remove oil filler cap.

3. Place your palm firmly over the opening, sealing it. (attention: it is hot when engine is hot!)

4. If you feel pressure against your hand as if it is trying to push it off, the PVC system is malfunctioning.

5. A properly operating system will either have a slight suction on your hand or you won't feel anything at all (pressure or vacuum), which is more typical of high mileage cars.

The PVC system is made up of 3 hoses (2 inlet, 1 outlet), and two valves, per side of the car. 1 of the valves is a "check valve" located in the accordian inlet boot prior to the DK throttle motor and aft of the Mass Airflow Sensor. The "volume control valve" (bmw speak) is located down line of the check valve. This valve has another inlet hose coming off the valve cover. The outlet of the volume control valve then goes to the large plenum of the intake manifold. The plenum is the large box before the intake runners then dart to the opposite side of the engine.

About 40 bucks each at most dealers, and there are left and right volume control valves. Don't replace the check valves in the intake boots, they never fail as only air moves through them. The volume control valves since they are sucking oil from the valve cover do clog up. Some have cleaned them with success but I'm not a believer in cleaning these after trial and error.

The first indicator of PCV (volume control valve) failure is high oil consumption of about 1 qt every 400-500 miles or even more.

Last year we have made extensive tests on this, Hairywithit (my wrenching buddy) even made for my 750 a test installation with an oil trap shown here

http://twrite.org/shogunnew/upgrades...or_Shoguns_M70


http://www.ow.no/gallery2/main.php?g...d0d7b052cf176d
http://www.ow.no/index.php?option=co...d=23&Itemid=13
http://bmwe32.masscom.net/sean750/vc.../VCVvalves.htm

I disassembled a VCV valve to see the innards
http://www.pictureupload.de/bild/576...v_valvem70.jpg

[janimaki]

Is it possible to plug connections on intake plenum and intake boot and put crankcase ventilation filter to valve cover to test if high oil consumption is through VCV valves or if the problem is somewhere else ?
I have changed the valve stem seals, VCV valves and tested the compression put still the engine takes quite much oil and releases blue smoke when started.

[shogun]

Try to make a simple oil catcher, was mentioned here https://www.bimmerforums.com/forum/s...-M70-oil-catch
some more drawings and versions from the German forum http://www.7-forum.com/forum/5/v12-u...ung-52036.html
You need something that separates air and oil, for example here http://www.skygeek.com/airwolf-air-o...ator-kits.html

[IDEXPUNGED]

Quick question: My local parts place has a crankcase breather hose for cylinders 1-6 but not for 7-12; Could I substitute the part for cylinders 1-6 for cylinders 7-12?

[shogun]

Different part number, does not fit http://www.realoem.com/bmw/enUS/show...diagId=11_4618

[XAlt]

The improvised tubing on shogun's site I think would be more adept in the mean time.

[IDEXPUNGED]

Got the part, I can confirm that the part with part number 11-15-1-720-392 is identical to the one with the part number 11-15-1-720-393

Only one of the hoses is cross compatible between engine banks.

[shogun]

there must be a (at least a small) difference as there are different part numbers
393 https://www.ecstuning.com/b-genuine-...e/11151720393/
392 https://www.ecstuning.com/b-genuine-...e/11151720392/

but if it fits, go ahead