Photo DIY – BMW M54 6-cylinder Crankcase Ventilation (PCV) – 325i, 328i, 330i, 525i, 530i, X5 & Others
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.
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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).
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);
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).
6) Remove throttle cable (if applicable - later models have no cable) (page 110-11).
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).
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.
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.
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.
20) Disconnect the oil drain hose from the bottom of the oil separator (or just cut the hose).
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, www.bentleypublishers.com .
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
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.