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Photo DIY – BMW M54 6-cylinder Crankcase Ventilation (PCV) – 325i, 328i, 330i, 525i, 530i, X5 & Others

July 22, 2010

The Crankcase Ventilation System (also known as PCV, or Positive Crankcase Ventilation) on the BMW M54 6-cylinder engines 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.

See this Blog post link for more information:

BMW M54 PCV – Crankcase Ventilation System

Here’s a quick DIY on replacing the Crankcase ventilation system (PCV) on the BMW M54 6-cylinder engines.  Tools required are standard metric and mechanic’s tools.  The Bentley repair manual does not specifically address the crankcase ventilation system.  However, this DIY does reference some of the steps in the Bentley repair manual for the E46 chassis (3-series 99-05).

Click HERE for Bentley repair manual. 

Click HERE for Crankcase Ventilation System repair kit (includes all hoses and separator valve), after clicking, select your model.

Notes on M54 Crankcase Ventilation System repair/replacement:

A)      The older Bentley manuals do not directly cover this task .  However, most of the lead-up tasks are covered in the section on intake manifold replacement.  Newer editions of the Bentley manuals will include replacement of the PCV assemblies.

B)     We have verified that the intake manifold does not need to be removed to do the job.  Follow the basic steps in the Bentley manual, for intake manifold replacement, up to the point where they are prepping for the actual manifold removal.

C)    Be absolutely certain to clear out the oil return nipple on the dipstick tube.  The dipstick oil return tube on the car that was used in formulating this procedure (for a future Fast Times DIY article) was fully clogged with oil/water sludge.  Additionally, the hose from the oil separator to the oil return nipple on the dipstick tube (AND the oil separator itself) was fully clogged with the sludge.  In fact, ALL of the hoses were filled with the sludge.

D)    All of the hoses and fittings were either brittle and cracked apart as soon as they were moved …. or …. they were so deteriorated that they would collapse when handled.

Basic process for crankcase ventilation system repair, without removing intake manifold (page numbers refer to the Bentley repair manual for the E46 chassis, 3 series 99 through 03);

1)   Remove air filter box.

2)   Open harness loom at front of micro-filter tray and release the positive battery cable and sheathed harness.  Remove micro-filter and micro-filter tray (page 110-9).

3)   Remove fuel rail cover (page 110-9).

4)   While it is not required, removing the driver’s side e-box closure panel will help to give access to remove and install the various parts that we will be dealing with in further steps (page 110-10).

5)   Remove intake bellows.  Use care when removing the vacuum hoses from the plastic “F” fitting.  The fitting is likely brittle and can easily break (page 110-11).

6)   Remove throttle cable (if applicable - later models have no cable) (page 110-11).

7)   Unbolt wiring harness box (conduit) and pull it aside (page 110-12).

8)    Remove plug on throttle housing (only on cable drive models) (page 110-12).

9)    Disconnect harness plug from idle control valve (page 110-12).

10)   Disconnect harness plug from resonance valve (page 113-7).

11)   Disconnect harness plug from purge valve (fuel tank vent valve) (page 110-13).

12)   Disconnect vent hose from underside of purge valve (see photo above).

13)   Pull purge valve (with the rubber hanger) off of the metal hanger tab.

14)   Gently bend dipstick tube toward driver’s side, to gain additional clearance.

15)   Remove throttle body, by removing the four 10mm hex-head bolts, then pull out the throttle body.

At this point, we are ready to start removing the various crankcase ventilation hoses and oil separator.  While it is not specifically necessary to disconnect the fuel injector harness plugs and harness housing, this does give more room to work with the hoses that will be replaced.

16)   Disconnect fuel injector harness plugs and housing assembly (page 110-10).  Use a hooked pick tool to dislodge one side of the plug retainer clip.  It is not necessary to fully remove the clips, just dislodge one side and push it back a bit on the housing.  Once all clips are dislodged, pull the harness plug and housing assembly up, starting at the front.  It may be necessary to gently pry the plugs off of the injectors.

17)   Disconnect the valve cover vent hose at the front of the valve cover, just in front of the intake manifold (page 110-10).

Note the oil sludge filling the hose.

18)   Working above the manifold, near the fuel injectors, disconnect the intake manifold vent crossover hose at the rearward end and at the forward end, where it attaches to the main vent hose.  Be careful to not break the plastic manifold nipple at the rear connection point.  If you break the crossover hose or the forward connection to the main vent hose, this is not a problem since these will be replaced.

19)   Disconnect the main vent hose from the forward end of the manifold.  Be careful not to break the manifold connection nipple.

Check valve to Manifold vent hose filled with sludge

20)   Disconnect the oil drain hose from the bottom of the oil separator (or just cut the hose).

21)   Remove the two Torx-head screws securing the oil separator to the underside of the intake manifold (look at the new valve to see where the screws go).

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

22)   Work on pulling the oil separator out.  Typically, the valve cover hose and the main manifold vent hose are very brittle and as you pull and twist the valve, it will break the hoses.  If the hoses will not break apart, you will have to physically disconnect the hoses at the valve nipples (see the new valve).

23)   Remove all of the sections of the old hoses.

a.      Valve cover to oil separator hose

b.      Forward intake manifold to oil separator hose

c.      Upper intake manifold crossover hose

d.      Oil separator to oil return nipple hose

e.      Vacuum hose on oil separator, if applicable

24)   Clean the sludge out of the two upper manifold hose nipples and the valve cover nipple.

25)   Clean the sludge from the oil return tube on the dipstick tube assembly.  There is a 90-degree bend at the base of the dipstick oil return tube, just before it joins the main dipstick tube (where the dipstick goes through).  Anything that you would use to insert into the tube, to clear through the sludge, will not go past the 90-degree bend.  Connect a length of hose to the oil return nipple and try to blow through it (with the oil cap and/or the dipstick removed).  If you cannot freely blow through the hose, the oil return is clogged.  The easiest way to remove the clog is to apply compressed air to the oil return tube.  This can be accomplished via a blow-gun (connected to a compressed air source) applied to the hose, connected to the oil return, or some similar type of set-up.  Once the clog is blown through (into the oil pan), continue to apply the air in order to push the majority of the sludge through the tube.

Alternately, you can remove the dipstick tube as outlined in the Bentley manual (page 110-13), and clean it out.

**** Note that the main return hose (the one that goes from the upper end of the oil separator to the intake manifold) is twisted onto the nipple on the separator.  Position the hose, under the manifold, at about 90-degrees counter-clockwise to the installed position. push the hose-end over the separator nipple and then rotate the hose clockwise to lock it in place, and bring it up the the manifold connection nipple.  Do a test fitting of the hose to the separator nipple, before assembling either one into the vehicle … so you can see how it works.

26)   Install the oil separator.

27)   Install the various vent and return hoses.

28)   Install the throttle body.

29)   Re-assemble all of the hoses, electrical connections and brackets.

30)   Re-assemble the fuel injector harness assembly, if it was disconnected.  Note that while you should be able to snap the plugs into place on the injectors with the clips seated on the plugs, we have found that you typically must have the clips dislodged on one side (just as with the removal) in order to push the plugs into place.  Once the plugs are seated, move the clips into place on the plugs.

30) Install all of the remaining parts that were disassembled or removed.

Bavarian Autosport

  1. pete permalink

    how long will this take for a weekend mechanic?

    • Give yourself about 6-hours. We can do it in 3 to 4-hours, but we’ve done it before.

  2. Micah permalink

    what exactly are the symptoms of a bad crankcase ventilation system?

    • As noted in this post and the referenced link, the symptoms can vary depending on whether the system is clogged, has deteriorated and broken hoses, cracked valve assembly, ruptured check valve diaphragm, etc. Some of the typical symptoms can be: rough idle, oil smoke from the exhaust at start-up of while running, increased oil consumption/use, poor fuel mileage, or in the worst case, a total lock-up of the engine.

  3. Harold Cox permalink

    Very Helpful. My symptom is as follows:

    After three days of setting below freezine conditions.
    Started 2001 x5 and let warm up.
    Drove up road and smoke filled interior.
    Stopped and oppened hood and saw lots of oil on passenger side of engine.

    Runs fine but it appears that lots of oil came out at valve cover gasket.

    Assuming it is a bad separator (pcv).
    No water in oil.
    Runs fine.
    No over heating.
    What a mess.

    Would you agree with my assumption and what parts do you recommend me changing with the pcv?


    • The oil separator/check valve or one of the hoses is likely clogged (and was also frozen). This would cause pressure to build up in the crankcase. The valve cover gasket is the typical area that will blow as the pressure builds. You will need to replace all of the crankcase ventilation hoses and the valve, as well as the valve cover gaskets.

      See the original post for the link to the PCV kit.

      Click HERE for Valve Cover Gasket Set
      BMW M54 valve cover gasket set

      Click HERE for Valve Cover Nut Seals
      BMW M54 valve cover nut gaskets

  4. Ed Woznicki permalink

    Wonder if you have any hints for getting the dipstick tube back in, seems like i am missing something or overlooking some alignment issue? from the mounting bolt hole I can see I need to go in about another 3/8 to 1/2 inch. removed old “o” ring and put new one on dip stick tube, lubed with oil?

    • The tube does not have any stops or detents prior to the crimped flange that seats against the pan. Yes, you should lube the o-ring. Insertion should be a firm push with a twisting motion.

  5. Tom Englat permalink

    I think this site is excellent and appreciate it. I have a 1997 328I conv. and getting ready / studing on how I will change my pvc valve. Reviewing above steps and pictures I see some differences. I do not want to make any mistakes and I am wondering if I follow this will I be OK or should I look for more info. I have the Bentley repair manual but as stated it does not really cover this in detail. All help I get is appreciated. Thank you for this site. It is a great help. I am having a lot of fun and do not want to screw up!

    • Your 97 328i has the earlier M52 engine (vs. the M54 engine, that is covered in this article). The crankcase ventilation system does use an oil-separator/check-valve, but the layout is different. There is just one hose coming from the valve cover to the separator/valve and the valve is mounted directly to the intake manifold plenum. There is also the oil drain hose that goes to the dipstick tube.

      We have not done a DIY on this application. We’re not sure if this can be done without removing the intake manifold. We’d suggest that you remove the air filter box, MAF and associated plumbing to see if you can reach up under the manifold to access the separator/valve (and its mounting screws) and the hose connection to the valve.

      We do have a kit for this, that contains the valve, vent hose and the drain hose.

      Click HERE for M52 Crankcase Ventilation (PCV) repair kit

      BMW M52 PCV CVV crankcase ventilation  - oil separator repair kit

  6. Steven Kamyk permalink

    Thanks for telling me about this info on the Otto tip line, great job with the instructions. I will try to do this Saturday and let you know how it went.
    Thanks again, Steve

  7. Colby Richards permalink

    My x3 blew the valve cover gasket it started with a small oil leak dripping on the exaust.I just tightened the nuts little bit that stoped.I did not even think something like the ccv could blow it.So my wife has been driving it for a week or so and it started to make a little whistle sound and cel light come on with the lean bank 1+2+ codes I found some small tears in the air flo boot and siliconed them up.couple days engine light is back and and it is smoking bad when starting Aggggh 3 hours later I found this great diy.I am ordering the kit asap.checked the hose near the vc and it was very brittle, My car only has 55000mi on it dose it seem premature to have this problem? The lines dont have that nasty looking sludge in them well the 2 I have removed so far dont. I hope this solves the problem.
    Thank you for the great DIY,
    Colby Richards,
    Tampa, FL

    • Your lean fault codes and the smoking on start-up can certainly be characterized as symptoms for a partially or fully clogged oil separator or a ruptured diaphragm in the check-valve portion of the separator/valve assembly. While your mileage is a bit low, this would not be out of what could be considered normal.

      Let us know how it turns out, after the repair.

  8. Louie Lindner permalink

    Started my 2001 330CI to warm up on a below freezing day. Came back ten minutes later to severe smoke out of the tailpipe.(smell of burning oil). Got in,checked gages, revved engine gently, was running fine, sounded normal. Didn’t have time to investigate at that time so I shut it off and drove my truck. Later that evening I came back to investigate and the engine would not crank. Starter engages the flywheel but doesn’t turn over. I am praying that this is a hydrastatic lock condition from excess oil in the intake from the PCV system and the cylinder with the intake valve open ingested the oil. Haven’t pulled the plugs yet, but is this a likely senario? Thanks…great site….Louie

    • Pull the spark plugs and crank the engine (place a heavy towel over the spark plug holes so that you don’t blow oil all over the engine bay). As an alternative, if you have a suction pump, you could vacuum the bulk of the oil from the cylinders, then crank it. After pumping out the oil, install the spark plugs and try to re-start it. If it starts, it will be rough until the oil is burned away. At that point, go ahead and replace the ventilation hoses and the separator/valve.

  9. Trevor P. permalink

    ok so i got the whole ccv system out. you know the hose that runs from the bottom of the separator to the y on the dip stick holder? the inside of looked like it was melted. and some parts of it had been worn very thin. any idea what caused this?

    • This is just a very deteriorated oil drain hose (not uncommon). The new hose will cure this issue.

  10. Tim Van permalink

    I have an 2003 530i that last year had the crankcase ventilation system replaced (about 20k miles ago) However, when it is cold (below 20 degrees) and I am driving shorter trips (10 to 15 miles) I tend to find that brown-ish goo on the oil filler cap. If I drive the car for 1 to 2 hours or if the temp rises above 20 degrees, I find no signs of the brown-ish goo. I’ve consulted BMW dealers and independent mechanics that say it is common and I should not be concerned. My concern is that the repair was performed with warm weather parts rather than cold climate parts. Should I be concerned (i.e. replace with cold climate parts)?

    • Some condensation in the crankcase can be “normal”. In a colder climate, you can see this a bit more often. Additionally, long oil change intervals and short driving trips (short engine running times) will contribute to heavier condensation in the crankcase and, likewise, build-up in the ventilation system. To check what condition the oil separator and the oil drain are in, you could remove the oil drain hose from the dipstick tube nipple (or at the bottom of the separator … or both) and see if it is filled with sludge. If it is clear, you should be fine with the parts that are installed, at least for now. If the drain is filled with sludge, it’s time to consider replacing the separator/valve and cleaning out all of the hoses … or just replace them. What are your oil change intervals?

  11. durianhaven permalink

    All vent hoses/pipes of my ’05 X3 (M54) have braided heating wires. Not sure if they were active, but the symptoms previously described are there. Any problem if I replace them with normal cold-climate hoses?

    • We have not heard of any applications that have actively heated crankcase ventilation hoses (and can find no reference to this on the BMW parts micro-film, ETK). You should be fine with using the standard cold-climate parts.

  12. Valentin A permalink

    after i was done with all of this i put it all together back and when i started the car my EML , Engine light came on and when i try to accelerate my car purrs and does not have power. PLEASE HELP

    • 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.

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