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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > NA Engine (non-turbo) / Drivetrain / Exhaust Modifications > Crankcase ventilation system question



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      12-08-2018, 10:34 AM   #1
Cdutch513
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Crankcase ventilation system question

I'm trying to figure out what this part is. It's circled in red
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      12-13-2018, 07:00 PM   #2
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That may be a reference to the fuel tank vent line that connects to somewhere around the throttle body assembly on the intake manifold. It has similar connection like the crank case breather line connectors. That is one other thing that needs to be disconnected if you want to remove the intake manifold completely.
The other page on the right at Bentley Manual talks about the fuel tank vent line but on the picture there on the other page they show wrong connector as fuel tank vent. Also just noticed Bentley Manual is saying to remove the fuel rail for intake manifold removal, absolutely not necessary.
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      12-13-2018, 07:06 PM   #3
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Quote:
Originally Posted by PhaseP View Post
That may be a reference to the fuel tank vent line that connects to somewhere around the throttle body assembly on the intake manifold. It has similar connection like the crank case breather line connectors. That is one other thing that needs to be disconnected if you want to remove the intake manifold completely.
The other page on the right at Bentley Manual talks about the fuel tank vent line but on the picture there on the other page they show wrong connector as fuel tank vent. Also just noticed Bentley Manual is saying to remove the fuel rail for intake manifold removal, absolutely not necessary.
I appreciate the input. I'm troubleshooting excessive pressure in the valve cover. It's pushing oil out of the gasket and valvetronic motor gasket. My P3 gauge shows vacuum at the manifold, but it seems like it's not getting vacuum to the valve cover to open the PCV valve. All the lines are clean and clear. OCC is clear. Thinking it's the valve, but wanted to troubleshoot everything but doing a valve cover.
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      12-14-2018, 05:48 AM   #4
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It maybe stupid question but are you sure it is pressure causing the oil come out of the valve cover gasket and VVT gasket? They are known to leak oil by themselves. If you try to open the engine oil fill cap does it relieve pressure from there, or slight vacuum? The PCV is known to stuck fully open and cause extreme vacuum on the crankcase causing air getting in from crankshaft seals and squealing sound. Opposite of what you are describing. In those cases with NA engine opening the oil fill cap is difficult due to a lot of vacuum.

From your signature you have a supercharger added. Without it, the only thing that can make "positive" pressure is the blow by gasses in the crankcase. Then the only suspect would be the crank case ventilation (PCV) valve being stuck closed. That is its duty, to vent the crank case pressure to the intake in a controlled way. The PCV on these cars are more likely to stuck open because of dirt, or ripped off and venting to atmosphere. To be stuck closed it must be really filled with dirt.

With the supercharger installed I am not sure how it would be all working. You would have positive pressure on the intake manifold side from the supercharger. Then my guess the crankcase would only ventilate when its pressure rises up same level as the intake manifold pressure from the supercharger. That would mean your crankcase pressure will be higher than an NA engine all the time. But the supercharger system you have might have some modifications to make it work as NA system. You mentioned oil catch can OCC too.

I don't know how you would see vacuum on the intake manifold with supercharger also, but again I am not familiar with superchargers. Maybe at idle or low rpms the supercharger doesn't provide much pressure and behaves like NA?
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      12-14-2018, 12:16 PM   #5
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Im 90% sure that is excessive pressure. The oil was only leaking from the Valvetronic gasket to begin with. I removed and replaced it and used a bunch of RTV. Now the leak from there is negligible and its leaking around the vcg on the hot side.

I pulled the oil filler cap off after a drive today and it seemed to want to be pushed off. like there was some pressure in there. Wasn't anything crazy though. I do have a lot of oil vapor escaping from the oil filler cap when I take it off. Best way to describe it is a lit cigarette left alone. I also removed the line that would go to the intake manifold just now and oil vapor was funneling out the same way.

The best way to describe the new set up with the supercharger from the bottom picture is the valve cover line goes to the oil catch can then exits to the intake(non compressed) side of the supercharger. The bottom hose on the picture is now capped off.

The supercharger has been installed for around 60,000 miles and this wasn't an issue until I removed and reinstalled the valve cover when doing the eccentric shaft sensor. All new gaskets were used.

The supercharger only creates boost when under load. Most times driving I dont see any boost because I hardly get into those high load situations. Im not exactly sure how this works because the serpentine is always spinning, but I was told by numerous people that it does and the P3 gauge proves it.
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      12-15-2018, 02:04 PM   #6
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The vapor coming out of oil fil cap or the breather line from valve cover is the blow-by gases and expected. I can't tell if it is a lot or normal in your case. If you are getting vapor out of the valve cover breather tube it means your PCV is not stuck closed.

Is it possible some part of the valve cover gasket got rolled and pinched at a point during installation and so not sealing well? It is not uncommon. I would check with a inspection mirror all around

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      12-15-2018, 02:09 PM   #7
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Quote:
Originally Posted by PhaseP View Post
The vapor coming out of oil fil cap or the breather line from valve cover is the blow-by gases and expected. I can't tell if it is a lot or normal in your case. If you are getting vapor out of the valve cover breather tube it means your PCV is stuck closed.

Is it possible some part of the valve cover gasket got rolled and pinched at a point during installation and so not sealing well? It is not uncommon. I would check with a inspection mirror all around
Thank you for all the info! I greatly appreciate it!
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      12-15-2018, 02:11 PM   #8
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I am sorry, I wrote wrong, your PCV is NOT stuck closed.
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      12-15-2018, 02:12 PM   #9
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I am sorry, I wrote wrong, your PCV is NOT stuck closed.
But if there is no vacuum and it's having oil vapor leak out would it be stuck open? So how is there excess pressure?
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      12-15-2018, 02:30 PM   #10
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Quote:
Originally Posted by Cdutch513 View Post
But if there is no vacuum and it's having oil vapor leak out would it be stuck open? So how is there excess pressure?
This may give you more info how the system works:

https://www.e90post.com/forums/showt...ght=crank+case

Each time there is combustion at the combustion chamber as engine is running, some of the combustion gas makes its way passed the piston rings into the crank case. The piston rings do not provide a 100% seal. The gas that goes passed the piston rings into the crank case is called blow-by gas.
If crank case was fully closed, with each combustion more and more blow-by gas would fill it and raising its pressure. This blow by gas has to go (vent) somewhere. For emission reasons, modern engines take the blow-by gas and reroute it to the intake so that it gets burned again in the engine.

The PCV (Positive Crankcase Ventilation) valve, is there to relieve this pressure, hence the positive in its name. But it does so in a controlled way. You have pressure in the crankcase, vacuum in the manifold, connect to the too, intake will suck from crankcase. Put the PCV valve in between which only allows controlled amount of gas flow from crank case into intake, then it is good.

When you open the oil fil cap or the vent line from valve cover, you are now venting the crank case to the atmosphere. You don't need vacuum to pull the blow-by gases out. They are being pumped in small amounts with each combustion in the crank case resulting in positive pressure. Open the crankcase any point, they will vent out. The volume valve cover closes is part of the crank case volume.
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      12-15-2018, 02:54 PM   #11
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Ive looked over that thread so many times. It is very different though because thats the N51(I believe) and it has the pcv valve and cyclone separator built together. The separator on mine is underneath the manifold and no longer connected. It hasn't been since the supercharger install.

I think I understand all that. I want to do a compression test to make sure that its not leaking too much.

I guess the main thing at this point is the cause of the leaking oil. I reinstalled the valve cover and oil started leaking. Couldn't tell from where so I replaced all the gaskets again. It continued to leak and I noticed it was all coming from the actuator gasket and leaking into the crevices of the valve cover. It would only smoke when making sharp left turns. Which makes sense because it was throwing the oil onto the headers. I didn't have any oil on the engine block where the valve cover connects at this time. I thought maybe I got another bad gasket(from FCP Euro) and got another one. I installed it with a bunch of RTV and now it leaks from between the valve cover and the block. Thats why I think its excessive pressure. It only leaks on the lowest side of the engine.(hot side) Before I sealed the actuator gasket, that was the weakest point, and now because that part is completely sealed, it has found the next weakest part.

I just wish the thing would burn to the ground lol
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      12-16-2018, 09:25 AM   #12
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I believe I have a slight vacuum in my magnesium valve cover, I understand this to be healthy, using the intake manifold airflow to pull a small volume of air through the hoses to relieve that pressure you're experiencing.

If you still have a plastic valve cover, I think they all have an oil separator internal to it? Which may be causing problems...? If you've added a 3IM and another oil separator bolted on to it, could you possibly now have 2? RealOEM is unclear on where some hoses connect to but there are great threads on this forum.

I'll eventually be on an inner DISA repair in that area myself. Just doing a little research for now. It seems quite involved with all of the electrical / CCV hoses in the way.

Hopefully you are able to solve your issues peacefully, these cars are worth keeping alive and even better when not leaking oil all over the place.
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