Squeal when adding OEM PCV flapper

pysical

Sergeant
Jun 16, 2017
471
108
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2009 335xi E90
I have the VTT billet valve cover and dual catch can setup and this is my current setup:


except I am not using the breather.

I removed the filter from the high side catch can and ran a line to my turbo inlet. In line, I added the pcv flapper. Since doing that I get a squeal when idling. Should I run it without the flapper? I was trying to put it back to as close to the RB/BMS setup I had on the stock valve cover since I think I am experiencing some turbo oil drain issues. My bottom mount single drain has some oil buildup around it.
 

Tuppidsay

Corporal
Aug 3, 2017
116
63
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Seattle, WA
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2008 535i
best bet is to restrict the line from the manifold or remove the flaper. Either options will work but restricting the vacuum line will stop issues with what is essentially a "vacuum" leak. Tuning can overcome that if u want to just delete the flapper. I run the same vtt system but without the aftermarket cover without a flapper valve. been fine for 75k miles
 

pysical

Sergeant
Jun 16, 2017
471
108
0
Ride
2009 335xi E90
best bet is to restrict the line from the manifold or remove the flaper. Either options will work but restricting the vacuum line will stop issues with what is essentially a "vacuum" leak. Tuning can overcome that if u want to just delete the flapper. I run the same vtt system but without the aftermarket cover without a flapper valve. been fine for 75k miles
What do you mean by restrict? I removed the flapper and so it goes VC -> CC -> Inlet.
 

Tuppidsay

Corporal
Aug 3, 2017
116
63
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Seattle, WA
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2008 535i
Your post said you installed the pcv flapper and got a squel. That's caused by too much vacuum in the crank case. It's literally air being drawn in around the crankshaft seals. Either remove the flapper (may cause not enought vacuum at idle, ie turbo drainage issues) or leave the flapper and lower the amount of vaccum to the crankcase by restricting the vacuum hose from the manifold to the catch can. This problem is why VTT came out with the vaccum relief valve accessory. I personally run the vtt setup with no flapper and it's fine but I have a factory cover and twins. I have a client that is single with the bms/rb setup with the flapper and hasn't had issue either. Your mileage may very. Id suggest getting yourself a cheap manometer, making an oil filter cap adapter, install the flapper, and then "tune" the amount of crankcase vacuum to near stock levels via restricting orafices inserted into the manifold vaccum line to the catch can. OR buying the vtt vacuum releaf valve that vtt sells and adjust it to where you get the stock levels of crankcase vacuum.

Good Luck
 

TheLittleOne

New Member
Apr 26, 2020
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30 Jahre M3
Your post said you installed the pcv flapper and got a squel. That's caused by too much vacuum in the crank case. It's literally air being drawn in around the crankshaft seals. Either remove the flapper (may cause not enought vacuum at idle, ie turbo drainage issues) or leave the flapper and lower the amount of vaccum to the crankcase by restricting the vacuum hose from the manifold to the catch can. This problem is why VTT came out with the vaccum relief valve accessory. I personally run the vtt setup with no flapper and it's fine but I have a factory cover and twins. I have a client that is single with the bms/rb setup with the flapper and hasn't had issue either. Your mileage may very. Id suggest getting yourself a cheap manometer, making an oil filter cap adapter, install the flapper, and then "tune" the amount of crankcase vacuum to near stock levels via restricting orafices inserted into the manifold vaccum line to the catch can. OR buying the vtt vacuum releaf valve that vtt sells and adjust it to where you get the stock levels of crankcase vacuum.

Good Luck
Hey man Im trying to run the same setup as you but im having trouble. Im trying to use the VTT dual cans with the stock valve cover stock twins recirculating into the inlet. I set everything up and the car is idling super rough with a couple vacuum codes. Was wondering if you had the same problems and how you fixed it.
 
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pysical

Sergeant
Jun 16, 2017
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108
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2009 335xi E90
Your post said you installed the pcv flapper and got a squel. That's caused by too much vacuum in the crank case. It's literally air being drawn in around the crankshaft seals. Either remove the flapper (may cause not enought vacuum at idle, ie turbo drainage issues) or leave the flapper and lower the amount of vaccum to the crankcase by restricting the vacuum hose from the manifold to the catch can. This problem is why VTT came out with the vaccum relief valve accessory. I personally run the vtt setup with no flapper and it's fine but I have a factory cover and twins. I have a client that is single with the bms/rb setup with the flapper and hasn't had issue either. Your mileage may very. Id suggest getting yourself a cheap manometer, making an oil filter cap adapter, install the flapper, and then "tune" the amount of crankcase vacuum to near stock levels via restricting orafices inserted into the manifold vaccum line to the catch can. OR buying the vtt vacuum releaf valve that vtt sells and adjust it to where you get the stock levels of crankcase vacuum.

Good Luck
I just wasn't sure why adding the flapper would cause it when it didn't do it with the stock valve cover. The setup was the same.

Stock:
VC -> Flapper ->CC -> Turbo Inlet

VTT:
VC -> CC -> Flapper -> Turbo Inlet
 

Tuppidsay

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Aug 3, 2017
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Seattle, WA
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2008 535i
The adapters to connect the factory valve cover and the internal passages provide enough vacuum restriction to keep things happy. One of the advantages to the aftermarket covers is the larger more free flowing connections for pcv operation. Thus more vacuum getting to the crank case. This is great for during boost and situations that would cause high crankcase pressure. But creates more work when trying to implement a vacuum and pressure type system like factory.
 
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pysical

Sergeant
Jun 16, 2017
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2009 335xi E90
The adapters to connect the factory valve cover and the internal passages provide enough vacuum restriction to keep things happy. One of the advantages to the aftermarket covers is the larger more free flowing connections for pcv operation. Thus more vacuum getting to the crank case. This is great for during boost and situations that would cause high crankcase pressure. But creates more work when trying to implement a vacuum and pressure type system like factory.
Thanks. I think I am going to go back to the stock valve cover and RB/BMS catch can setup. This VTT shit has been nothing but oil leaks, oil consumption, and 2D2E. I had no issues with the stock cover.
 
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bronson

New Member
Nov 16, 2022
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07 e92
The adapters to connect the factory valve cover and the internal passages provide enough vacuum restriction to keep things happy. One of the advantages to the aftermarket covers is the larger more free flowing connections for pcv operation. Thus more vacuum getting to the crank case. This is great for during boost and situations that would cause high crankcase pressure. But creates more work when trying to implement a vacuum and pressure type system like factory.

Agree 100%! I did the VTT/M18 style aluminum cover, dual OCC (VTT diagram) and plugged head ports when replacing my cracked OEM cover and it has been nothing short of a nightmare getting things to run right afterwards... For further input to anyone considering going down the PCV rabbit hole when doing a VC gasket replacement-- don't.

For inexperienced DIYers theres a chance you may drop a plug into the engine when tapping the head ports or in an equally bad situation, you may snap the tap in the port while tapping, unless you're lucky enough where the tap backs out with an extractor, the head will have to come off or you can use the broken tap with some RTV as a plug hoping it doesn't leak. Don't ask how I know šŸ„²

The process of dialing in the excess vacuum in the crank case after (assuming you did everything else right), is also a nightmare waiting to happen. I went with the VTT vacuum relief valve and from personal experience, the only way I can stop the car from squealing at idle is to run it with no spring... I don't have a manometer and don't want to drill into the VTT oil cap to install an adapter either but that seems to be the only real way to dial in the crankcase vacuum to spec. Car will probably smoke like a train too.

If you insist on plugging the head ports when replacing anything VC related, I would just stick with an OEM style VC (aluminum or plastic), with the RB external PCV kit. Simple and from reading a ton of PCV related threads, it works.

Thanks. I think I am going to go back to the stock valve cover and RB/BMS catch can setup. This VTT shit has been nothing but oil leaks, oil consumption, and 2D2E. I had no issues with the stock cover.

Hope you got it all sorted out. I am still currently dealing with an intermittent 2D2E code after installing mines and have awful throttle oscillations at low RPM light throttle. Not sure if the oscillations is VC/PCV related but I never had these issues either prior to installing the VC. Car also smokes a good amount at idle. Going to replace both VANOS solenoids when they get in and if anyone is interested I'll post an update. Good luck.
 
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Jern54

Sergeant
Oct 18, 2019
288
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Netherlands
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E91 N54 335i
FWIW

I'm using a M18 valve cover without any issues.
Head ports plugged
External PCV with catch can connected to the throttle body
Stock flapper valve with VTA
Keep it simple
 

sosiiick

Lurker
Mar 25, 2020
17
4
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Agree 100%! I did the VTT/M18 style aluminum cover, dual OCC (VTT diagram) and plugged head ports when replacing my cracked OEM cover and it has been nothing short of a nightmare getting things to run right afterwards... For further input to anyone considering going down the PCV rabbit hole when doing a VC gasket replacement-- don't.

For inexperienced DIYers theres a chance you may drop a plug into the engine when tapping the head ports or in an equally bad situation, you may snap the tap in the port while tapping, unless you're lucky enough where the tap backs out with an extractor, the head will have to come off or you can use the broken tap with some RTV as a plug hoping it doesn't leak. Don't ask how I know šŸ„²

The process of dialing in the excess vacuum in the crank case after (assuming you did everything else right), is also a nightmare waiting to happen. I went with the VTT vacuum relief valve and from personal experience, the only way I can stop the car from squealing at idle is to run it with no spring... I don't have a manometer and don't want to drill into the VTT oil cap to install an adapter either but that seems to be the only real way to dial in the crankcase vacuum to spec. Car will probably smoke like a train too.
I have all these exact issues including the intermittent 2D2E code ever since. I never had smoking issues until I added the vc and occ. I went with the billet cover. It looks so good that I don't want to go back to the stock plastic cover. I'm currently running no spring in the relief valve. I cut the spring so short trying dial it in that it wasn't doing anything anyways. I also got the b58 coils from them. I am having misfire issues at higher boost now too. Its been a headache. I'm hoping I find a solution here soon.
 

bronson

New Member
Nov 16, 2022
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07 e92
I have all these exact issues including the intermittent 2D2E code ever since. I never had smoking issues until I added the vc and occ. I went with the billet cover. It looks so good that I don't want to go back to the stock plastic cover. I'm currently running no spring in the relief valve. I cut the spring so short trying dial it in that it wasn't doing anything anyways. I also got the b58 coils from them. I am having misfire issues at higher boost now too. Its been a headache. I'm hoping I find a solution here soon.

Following the diagram VTT provided on their website did not work for me. What I would do and what seems to have worked for me is to ditch the VTT ball style check valve on the low side and go with a spring/piston style check valve as well as adding an external PCV valve in the line running to your vacuum source. I replaced the VTT in-line check valve on the high side with a spring/piston style too.

low side: VC -> inlet of catch can
outlet of catch can -> external PCV valve -> check valve -> vacuum source

high side: VC -> check valve -> inlet of catch can
outlet of catch can -> VTA or recirculate to turbo inlet

I'm not sure if putting the external PCV valve in front of the check valve would make things run more efficiently but the way I currently have it hasn't caused me enough issues where I want to go back and redo the order; if someone has done it the other way around with better results I'd be open to give it a shot.

I would also replace the spring that you trimmed in your vacuum relief valve. Essentially, without the spring, we're just creating a huge vacuum leak to band-aid the squealing... The car will never run right that way. I ordered this kit off of Amazon for the replacement spring.
 

sosiiick

Lurker
Mar 25, 2020
17
4
0
Following the diagram VTT provided on their website did not work for me.
I'm not running a oil cap breather, but basically the setup listed on their website. I have a Radium OCC but VTT check valves. This is my current setup:
occ.png

Ordered a pcv valve and a new spring. Thanks. Ill let you know if it improves.
 
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