[RayLivingston]

The valve cover on my 335i has a pressure regulator screwed into it, which takes manifold vacuum, and, presumably, regulates it down to a lower, constant vacuum level. As that regulator is screwed in, it appears how FAR it is screwed in might be used to set the actual crankcase pressure. Is that true, or is the valve intended to just be screwed in fully?

I ask because I replaced the valve cover about a year ago, transferred the old regulator, and screwed it all the way in. The vacuum within the crankcase is MUCH higher than in my E46. The E46 is regulated to something really minimal like a couple of inches of water, while the is probably more like (just guessing here) 10 in-Hg. Removing the oil filller cap and putting my hand over the opening, the vacuum on the E46 is barely noticeable, while on the E90 it pulls my hand down quite strongly.

Is there a spec for the crankcase pressure on an E90?

Regards,
Ray L.

[dpaul]

I have not encountered a "screwed-in pressure regulator" on the valve cover any of the three N54 engines that I have worked on, so that part is new to me.

However, pressures are given in this document:

CRANKCASE VENTILATION SYSTEM DIAGNOSIS AND MEASUREMENT
TECHNICAL SERVICE BULLETIN
Reference Number(s): SI B11 03 08, Date of Issue: October, 2013

Pressures at idle in mbar:
N51*and*N52K 33
N52T 21
N54 17
N54T 14
N55 50.0*+/**8.0

There are other engines listed in the bulletin but I assume it is the N54 you are primarily interested in.

[RayLivingston]

Originally Posted by dpaul

I have not encountered a "screwed-in pressure regulator" on the valve cover any of the three N54 engines that I have worked on, so that part is new to me.

However, pressures are given in this document:

CRANKCASE VENTILATION SYSTEM DIAGNOSIS AND MEASUREMENT
TECHNICAL SERVICE BULLETIN
Reference Number(s): SI B11 03 08, Date of Issue: October, 2013

Pressures at idle in mbar:
N51*and*N52K 33
N52T 21
N54 17
N54T 14
N55 50.0*+/**8.0

There are other engines listed in the bulletin but I assume it is the N54 you are primarily interested in.

Hmmm.... I've got WAY more than that. 14mBar is about 0.2PSI, which is next to nothing, but that is roughly the same spec as the E46 (~5 in-H20, IIRC). But, as I said, on mine, When I put my hand over the oil fill hole with the engine idling, it is pulled down quite strongly.

The device in question is near the rear of the valve cover, on the intake side, screwed into a rear-facing cast-in tube in the valve cover. The valve is screwed into that tube. Very close-by is the plastic pipe that brings manifold vacuum from to the valve cover, where it is applied to one side of the valve, with the other side being open to the crankcase.

If you look at this picture (on the FCP Euro site):

https://dyw03owr7vs3n.cloudfront.net...ek.?1496436674

Look near the intake side, rear in the photo, and you see the metal clip that the engine cover fastens to. Just to the left of that are two cylindrical bosses, pointing to the rear of the cover. The one closer to the spark plugs is the one the manifold vacuum pipe connects to. The other one is the valve in question. In the photo, you can just make out the hex head of the valve itself, used to unscrew it from the valve cover.

BTW - The ONLY reason I even care, is that since I installed this valve cover last year, I've gotten random faults. I forget the number, but the fault I get is something along the lines of an "improbable" correlation between throttle position and manifold vacuum. With the exception of this fault, the engine runs perfectly, and consumes almost no oil (6-8K miles/quart @ 110K miles).

Regards,
Ray L.

[dpaul]

That screw-on cap houses the PCV valve - a check valve in the path between the inside of the valve cover (i.e. interior of the engine) and the intake ports of the cylinder head. That path is entirely internal to the valve cover.

The valve opens when intake manifold pressure goes below atmospheric (during deceleration, idle) allowing blowby gases that cause increased crankcase pressure to be evacuated into the intake ports and burned.

It closes when the pressure in the intake manifold rises above the crankcase pressure (as when under boost) to prevent undue increases in crankcase pressure.

The port on the valve cover next to the PCV valve housing connects to a hose/flapper valve assembly. That is a two way street - at low manifold pressures, filtered air comes into the engine through the flapper to make up for what is being extracted through the PCV valve. Under boost, the flow of gases is reversed, blowby goes out through the flapper into the pre-turbo intake piping, preventing increased crankcase pressure.

That PCV valve cap must be screwed all the way in (although be careful not to overtighten those plastic threads). It is not an adjustable device.

[mweisdorfer]

Originally Posted by dpaul

I have not encountered a "screwed-in pressure regulator" on the valve cover any of the three N54 engines that I have worked on, so that part is new to me.

However, pressures are given in this document:

CRANKCASE VENTILATION SYSTEM DIAGNOSIS AND MEASUREMENT
TECHNICAL SERVICE BULLETIN
Reference Number(s): SI B11 03 08, Date of Issue: October, 2013

Pressures at idle in mbar:
N51*and*N52K 33
N52T 21
N54 17
N54T 14
N55 50.0*+/**8.0

There are other engines listed in the bulletin but I assume it is the N54 you are primarily interested in.

I think he's taking about the crank case hose & sensor connected to the charge pipe & valve cover. There is a valve connected on that hose. The hose & valve that comes with the hose, along with the PCV valve should be replaced every 50,000 miles

[dpaul]

Originally Posted by mweisdorfer

I think he's taking about the crank case hose & sensor connected to the charge pipe & valve cover. There is a valve connected on that hose. The hose & valve that comes with the hose, along with the PCV valve should be replaced every 50,000 miles

I do not see any "crank case hose" connected to my chargepipe. I do not have any hose connecting the "chargepipe & valve cover". I have no idea what you are referring to.

Do you have a picture or can you point out this feature in a realoem drawing?

[mweisdorfer]

Originally Posted by dpaul

I do not see any "crank case hose" connected to my chargepipe. I do not have any hose connecting the "chargepipe & valve cover". I have no idea what you are referring to.

Do you have a picture or can you point out this feature in a realoem drawing?

My bad, meant that the crank case hose/ valve is connected to the firewall side inlet & the valve cover next to the PCV valve.

You can't see that in this pic, but you can see the hose / valve..

[IMG][/IMG]

[dpaul]

Yes, if you read my response, I discussed that hose which contains the flapper valve.

Getting back to the OP's question, there is no adjustable pressure regulator.

[Mayorie]

Originally Posted by dpaul

That screw-on cap houses the PCV valve - a check valve in the path between the inside of the valve cover (i.e. interior of the engine) and the intake ports of the cylinder head. That path is entirely internal to the valve cover.

The valve opens when intake manifold pressure goes below atmospheric (during deceleration, idle) allowing blowby gases that cause increased crankcase pressure to be evacuated into the intake ports and burned.

It closes when the pressure in the intake manifold rises above the crankcase pressure (as when under boost) to prevent undue increases in crankcase pressure.

The port on the valve cover next to the PCV valve housing connects to a hose/flapper valve assembly. That is a two way street - at low manifold pressures, filtered air comes into the engine through the flapper to make up for what is being extracted through the PCV valve. Under boost, the flow of gases is reversed, blowby goes out through the flapper into the pre-turbo intake piping, preventing increased crankcase pressure.

That PCV valve cap must be screwed all the way in (although be careful not to overtighten those plastic threads). It is not an adjustable device.

+1