DIY Video – Replacing the BMW M54 Crankcase Ventilation System, PCV, Oil Separator, Cyclonic Valve

The Crankcase Ventilation System (also known as PCV, or Positive Crankcase Ventilation) on the later model BMW V8 and 6-cylinder engines typically consists of a check valve (PCV valve), an oil separator and various vent and vacuum hoses. We have found that all of these applications (both V8 and 6-cylinder) have been experiencing failures of various parts of the system. The diaphragms in the check valves rupture, the check valves crack, the hoses deteriorate and oil sludge builds up in the hoses and valves that can partially or fully clog, or block, the system. We have designed kits for both the V8 and the 6-cylinder applications that give you everything that you’ll need in order to repair and renew the crankcase ventilation systems.

Click HERE for additional info on performing this DIY on the earlier M52TU engines

Follow along, with these three videos, as we perform the replacements on a 2001 325xi:


Below, is a photo of the check-valve/oil-separator and hoses, in the installed position.  This photo was taken on an engine that was removed from the vehicle.  You cannot see this view with the engine installed.  Photo used here, compliments of Bentley Publishing,

A = Oil drain hose
B = Inlet hose, from valve cover
C = Outlet hose, to intake manifold
D = Check-Valve/Oil-Separator assembly
Arrows = upper and lower mounting screws

In the DIY videos, we replaced all of the hoses and the oil separator and check valve, on the M54 (and M52TU) 6-cylinder engine. The system consists of a number of ventilation hoses, an oil separator and check valve and an oil drain-back hose. The system is well known to have problems with vacuum leaks due to hose and valve deterioration and cracking, as well as clogging due to sludge build-up in the hoses, valve and oil drain-back.

We typically get into the system when we see the symptoms appear, such as; oil burning, rough idle, engine fault codes that suggest air/fuel mixture problems or oxygen sensor problems and other symptoms that would suggest vacuum leaks in the system’s ventilation hoses or a ruptured check valve diaphragm. We have also seen what could be considered a catastrophic level failure which causes the cylinders to ingest oil right out of the crankcase and into the intake manifold and finally the cylinders … causing hydraulic lock. We are typically seeing these systems fail at mileages between 50,000 and 100,000. With these thoughts in-mind, you certainly would not go wrong in performing this task as a preventative maintenance operation.

Most (if not all) US model M54 (and M52TU) engined BMWs were delivered with the standard warm weather systems. The kits that we offer includes the hoses and valve assembly from the “cold weather” package. The hoses and valve are insulated with molded foam insulation. This can help to prevent the build-up of condensation in the hoses and the separator valve (which leads to sludge build-up and possible clogging of the ventilation hoses, valve or the oil drain hose). Even if you do not live in the northern climates, these parts are a good choice and will help to prevent the sludge build-up in the system.

In the early days of these failures, the generally accepted repair procedure (in order to replace the hoses and the valve) was to remove the intake manifold for access to all of the parts. We have found that the repair can be accomplished without removing the manifold. This greatly reduces the complexity and time of the repair.

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38 thoughts on “DIY Video – Replacing the BMW M54 Crankcase Ventilation System, PCV, Oil Separator, Cyclonic Valve

  1. I did this job on my ’03 330i last month. I REALLY appreciate you guys putting up the preliminary photos and instructions on the blog in advance of the newsletter and video release. I was looking forward to the final guide (and didn’t even realize there was going to be a video), but with the symptoms I was seeing I was afraid to let it go any longer. I could NOT have done it without your guide – you got me through it for under $200, as compared to the $900-1100 for parts + labor I was quoted by two shops.

    Thank you!

    I wish I had been lucky enough to have had your video guide available at that time; at a quick glance I can tell that it would have saved me at least a couple of hours and immeasurable sanity, especially in dealing with that twist-lock hose. Anyone doing this job from now on, with this video available, should consider themselves very fortunate.

    As a side note, for whatever reason, I chose to remove my dipstick tube for cleaning, which your article mentions as an alternative to merely blowing it out with compressed air. I had an extremely difficult time reinstalling it, because of the tight fit of the o-ring, tube, and the receiving hole in the engine, and it was also a very hard-to-reach area. Maybe I was missing some key trick, but personally I’d recommend against removing the dipstick tube unless really necessary.

    1. This write-up does not specifically cover the V8 engines (M60 & M62). However, these engines do have PCV issues. The PCV check valve has a rubber diaphragm that ruptures and causes many of the similar symptoms as noted for the 6-cylinder models. The check valve is incorporated into the rear intake manifold cover. See the links below for additional info.

      BMW M60 and M62 V8 PCV check valve issues #1

      BMW M60 and M62 V8 PCV check valve issues #2

      BMW M60 and M62 V8 PCV check valve issues #3

  2. Tsatsu commented:

    2002 E46 325i RWD, sport package
    M54 engine, manual transmission
    120,000 miles

    Hi Otto:
    I live in upstate NY and I appreciate you providing more insight into the crankcase ventilation system in your Winter newsletter. Over the last 3 years I have had the oil separator changed at least once a year (sometimes twice) due to sludge buildup. I usually get the classic symptom of the white smoke puff on startup, which later develops into smoking while while driving, and in one extreme case it did hydrolock at idle. Spark plugs were replaced after that incident at around 100,000 miles.

    Anyway this part has been replaced under BMW’s 2year warranty at the dealer each time. However they are at a loss as to why I keep getting the issue and they have no advice on how to prevent it. Each time they claim to have replaced the hoses and used the winter components (with insulation around the valve). At one point they even employed a BMW “fix” which required drilling a hole in the dipstick tube to allow additional venting. Each time I get the issue there are no error codes and the MIL does not come on.

    I change the oil around every 7500 miles, and I use the BMW synthetic oil. I also only use 93 octane fuel. The car runs smoothly. The only difference is that on cold days there is a whistling type of sound at specific rpms (around 2000 rpm and 3000 rpm). This sound usually goes away after the car is warm. The dealer doesn’t think this is an issue but that is the only think out of the ordinary with the vehicle operation. Most of my commutes are at least 20 mins long.

    Can you provide any insight as to on the cause of the problem or any advice as to what I should be doing differently?


    1. Point one:
      The hole drilled in the dipstick tube will create a vacuum leak and will disrupt the engine management to some degree. Not such a good idea. In this case, we would recommend replacing the dipstick tube to get rid of the hole and use the newer updated version that have been modified so that the oil has a clearer drain path through the tube and into the crankcase (see link below). We do not always perform this upgrade, but in your case, we certainly would recommend it, both in light of your frequent sludge build-up and the drilled hole.

      Click HERE for updated dipstick tube for E46 RWD, E39 and E85
      Note that there are various part numbers for different models. Contact our agents at 800-535-2002 for proper applications:

      Point two:
      Since you are in a cold climate and you have a comparatively short commute time (not really long enough to fully burn off the built-up condensation in the oil)), we would recommend a shorter oil change interval in the cold weather, such as 3000-ish miles.

      Point three:
      The whistling is likely a vacuum leak …….. perhaps the drilled hole in the dipstick tube. Of course, a hose or bellows may be leaking as well.

  3. One issue I noted when doing this job on my 2001 X5 3.0 the drain back hose from the bottom of the valve back to the dipstick is too short by about 8 inches. Maybe this should be noted because the dipstick in the X5 with M54 engine is mounted further back than in other models. Other than that the videos were an immense help in doing this job.

  4. First of all, great video DIY! I’m considering doing this job myself on my 2001 BMW 330i and was curious if there was a list of recommended tools?

    1. Well, let’s see:

      * Flexible hose clamp driver # 53910

      * 1/4″ drive metric ratchet and long, medium and short extensions. A universal joint may also come in handy.

      * 1/4″ drive Torx bit set

      * Needle-nose pliers (to pinch hose release clamps)

      * X-Acto or other razor knife (to cut oil drain hose, for easier removal)

  5. I have an oil leak which seems to be coming from the area of the oil seperator(2000 323i 175000mlsI can see oil on the engine block below the oil seperator so i plan to change it out soon. I already did the oil cooler hoses and the power steering with new reservoir. If there is anything i need to know thats a problem with this car(oil leaks) please let me know if it’s not too much trouble. I appreciate the time that you guys take to help us bmw lovers out here in life’s journey.
    Gregg(San Diego,ca)

  6. Also how can i get one of those extensiin thingees with the bit on on end and the rachet that turns like a gear assembly???

  7. Just had the pleasure of my VC gasket blowing out on the highway. Was throwing out a smoke screen – pulled off and quick look underneath – flames coming from the under engine tray. opened the hood and started throwing all the snow i could get my hands on under there. 5 mins and a 911 call later and it was out. scary moment for the family. Will be ordering the repair kit tomorrow.

  8. Hi,

    Thanks for the great video! I have a question about blowing out the return line. It sounds like you connect a hose to the dipstick return nipple, and then blow compressed air into the hose. If that’s correct, where does the air & sludge exit? How do you keep the sludge from being blown into the oil pan?

    Also, seems like if you’re this far into the repair it might make sense to clean/replace the idle control valve while you’re there. Would you agree?

    Thanks again

    1. Yes, any sludge does go into the crankcase. We recommend an oil change after the repair is complete, if there was indeed blockage in the drain-back tube. If you do have blockage and you do not want to blow it into the oil pan, you would have to remove the dipstick tube and clean it out.

      You also certainly would not go wrong in cleaning the idle control valve while you have ready access to it.

  9. Hello Otto,

    I just received the kit to replace the crankcase ventilation system in My 2004 X3 2.5L. After visiting a shop where mechanic checked two codes (engine service soon light was on) they indicated also than it is the Valve Separator. With your video removing was relatively easy & assembly with some problems of finding screw location to the Valve Separator was generally successful. I just put all together, started the engine and to my disappointment engine was shaking and important lights appeared on the dashboard ( Break, Service Engine Soon, EML and 4×4 below the triangle with an arrow). Initially I assumed than I did not connect some electrical housings. I removed again the bracket, the throttle body hose to double check. All was connected including PCV pipes.
    What I did wrong? What did happen during assembly?
    Did engine run because of disconnections or took some air and has more problems just temporary. I need your professional help.

    I will greatly appreciate your quick response.


    1. Try turning the ignition key on to the RUN (or IGNITION) position, but do not start the engine. Leave the key in this position for 5-minutes and then turn it off.. Restart the engine and see if all of the warnings are gone. Let us know what you find.

  10. Hello Otto,

    I turn ignition to the run postion for 3-5 minutes and started the engin again after that. It baheved the same way. At this moment I still have a loose bracket and throttle body open wtihout the hose. Do I have to disconnect a batery for some time. Can I do it without loosing some codes or disturbing computer? When I initially removed the oil return hose it was completely collapsed. Instead to have a round shape it was flat without the ability to flow. How to clean an idle control valve?

    1. Typically, those who have had these EML and code issues after installing a new crankcase ventilation system have been able to clear the EML by performing the procedure with the ignition key as noted above. Some installers have noted that waiting a minute and then pressing the throttle fully to the floor 3 to 4 times, then turning the key off, has worked for them. This has typically extinguished the EML warning, but may leave the CHECK ENGINE light on. In this case, check the stored codes and then clear them. They should not return.

      Additionally, a couple installers have noted that they did find that the throttle body or the idle control valve harness plug was not fully plugged in.

      The battery does not need to be disconnected … other than for common shop safety practices.

      Typical cleaning of the idle control valve involves using carburetor or throttle body cleaner and a rag or Q-tips.

  11. Your repair kit (as shown on page 4 of your Winter ’11 issue of Fast Times) includes a length of small diameter rubber hose. Where does that go?

    1. The length of vacuum hose that is supplied in the kit is for the fuel pressure regulator on M52TU engines. The hose runs from the nipple on the check-valve/oil-separator assembly (hidden under the foam insulator housing, on the new cold-climate valve assembly) to the fuel pressure regulator at the front of the fuel injector rail. Non-M52TU engines do not use this hose.

      The M52TU engines are installed in the following models:

      323i/ci/conv./wagon, 328i/ci 99-00
      528i/wagon 99-00
      Z3 2.5/2.8 99-on

  12. Also, how critical is putting in a new throttle body gasket? Would it be helpful to include that in the kit if it’s important to replace it once the throttle body is removed?

    Thanks for the great videos!

    1. If the throttle body gasket is original, we would recommend replacing it. We do not include the gasket in the kits due to the variation in the different engine applications (this would create quite a bit more unique kit part numbers). We offer the gaskets separately and suggest that you purchase one when purchasing the main PCV kits.

  13. Hello Otto,

    Thank you very much for your help. I did the following procedures:
    keep the ignition key to the start position for 5 minutes.
    After 5 minutes move the throttle pedal to the floor 4 times keeping the pedal by the floor for about 30 seconds eeach time.
    Return the key to release postion and after 30 seconds start the engine. All lights disapeared except the Service Engine, but this one I need to recode. Engine runs perfectly now. (All throttle hoses and air filter need to be in final assembly postion).
    Thanks again. I hope I will be able to recode Engine Service light and I will enjoy my X3 again.

    1. Great, Roman, We’re glad that “we” (you) got the EML faults cleared up. We’ll make a separate blog post on this. Once you reset the CHECK ENGINE fault codes you should be …. all clear!

  14. What a great diy video.I would recommend this video, To anyone interested in doing this job themselves.I watched this video 4 to 5 times.And each time, I got something new out of the video.What a great job you did on making the video.Keep up the good work.Thank you very much Kenny.

  15. Thanks for the reply.

    I have a 323i 99 e46.
    I received my kit today and unboxed,noticed a hose clamp and an O-ring. Why do these go?

    Also, the Vacuum Hose, im guessing my car carries it, but when i take out the parts in the car i will verify, or maybe you can elaborate on installation. (I’ll follow the line if there is 1.

    Part# 11157520035 (Vent Pipe) has 1 end with a clip connection end and the other end with a tube/hose end(no clip as the video vid#3 @ 4:10. Is this the way the 99 model is? And, is that the reason for the hose clamp supplied in the kit? The O-Ring still has me puzzled though.

    Ish (NYC)

    1. * The hose clamp is indeed for the other end of the hose that has no quick connect.

      * The vacuum hose goes from the oil-separator/valve to the fuel pressure regulator at the front of the fuel rail (if used).

      * The o-ring is for the oil dipstick tube. If you doe not remove the tube, you will not need the o-ring.

  16. I don’t see the videos. There is just a blank spot below where it says to follow along. I’ve tried viewing this page in both Internet Explorer and Google Chrome. Anybody else having this problem? Any ideas?

    1. Your computer must have FLASH installed and you must be able to view YouTube videos. If YouTube viewing is restricted, you will not be able to view the videos.

  17. Hi Otto
    Great DIY video. I took this job on my 03 325i M54 engine and replaced the valve and all 4 connecting hoses. I also replaced the Throttle body gasket. The job went smooth and the hoses all twisted or snapped into place perfectly.I got it all put back together fired it up and now I have alot bigger vacuum leak than before. It fires up and idles ok but when I press the gas it bogs then revs up. It now also makes a sucking sound about 2 seconds after I shut it off. I have sprayed starting fluid around all connections associated with the oil seperator and found no leaks. The leak does sound like it is comming from underneath the intake manifold.
    Could I have hit something underneath the manifold and caused a new leak or do you know anything that it could obviously be that I am overlooking before I take it to the BMW shop for a smoke test.
    Thanks and I look forward to your reply.

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