Valve Cover Breather Air

[mnetwork]

Is it normal to feel air coming OUT of the valve cover breather port? I always thought this was supposed to suck air in...

 

[XiKeiyaZI]

On the side? Above the Thermostat?

No, that breaths OUT. Supposed to circulate back into your intake or a catch can.

 

[mnetwork]

On the side? Above the Thermostat?

No, that breaths OUT. Supposed to circulate back into your intake or a catch can.

I keep reading different things then.. so if the port above the thermostat breathes OUT of the valve cover, then everything is normal?

 

[XiKeiyaZI]

Yup!

It's simply there to relieve any pressure build up. A lot of people will either slap a small breather filter on there (ghetto) or run a catch-can setup because oil deposits flow from that as well. If you run a catchcan or breather filter, it will clean up your intake system by not allowing the oil to build up in your piping/ic/TB.

Either way, it's there for a reason. ;D

 

[mnetwork]

Yup!

It's simply there to relieve any pressure build up. A lot of people will either slap a small breather filter on there (ghetto) or run a catch-can setup because oil deposits flow from that as well. If you run a catchcan or breather filter, it will clean up your intake system by not allowing the oil to build up in your piping/ic/TB.

Either way, it's there for a reason. ;D

See... here are my questions...

Where is this air coming from that is blowing out?

How does the PCV system come work with this?

 

[XiKeiyaZI]

You're reaching the boundary of my understanding of the PCV system functionality. ;3

I know that some pressure can be built up in the crankcase by whatever means. The Breathers up top are there to help relieve any and as much pressure as possible as it's built up. Failure to do so can disrupt the engine and even lead as far to blowing rings as pressure can build up underneath them.

This can also happen if the check valve that has a hose running from the VC to the intake manifold is malfunctioning and allowing boost into the valve cover. The check valve allows air OUT of the VC, but not in. This results in unwanted pressure.

The breather valve from the SIDE of the VC above the thermostat should work both ways, I believe....Edit : It allows any pressure that builds up while the car is OUT of vaccum and cannot be fed directly back into the manifold, the be fed into the intake system Pre-Turbo.

Example : While normal driving, out of boost.. both breather valves freely feed pressure back into the intake system. DURING Vaccum, the Valve on the back of the VC closes so as to not allow boost into the VC. The side breather then has pressure PULLED from it during boost. This relieves the engine of any unwanted pressure at all times without allowing any other pressure to build in the crank case.

;D

 

[bane3d]

http://www.dsmtuners.com/forums/articles-engine-fuel/366890-4g63t-pcv-system.html

d

 

[TSiAWD666]

The side above the thermostat is not a vent but rather it's an intake for the crank case. When the PCV opens under vacuum the gases in the crank case are sucked into the intake manifold. This leaves creates a vacuum in the crank case and so fresh air is sucked in from the port on the thermostat side.

Putting a breather filter there connected to atmosphere rather than the intake piping post MAS results in unmetered air being sucked into your engine during vacuum. Will it work? Sure, but not as well as it would with metered air.

 

[mnetwork]

The side above the thermostat is not a vent but rather it's an intake for the crank case. When the PCV opens under vacuum the gases in the crank case are sucked into the intake manifold. This leaves creates a vacuum in the crank case and so fresh air is sucked in from the port on the thermostat side.

Putting a breather filter there connected to atmosphere rather than the intake piping post MAS results in unmetered air being sucked into your engine during vacuum. Will it work? Sure, but not as well as it would with metered air.

If this is so, then why does oil get in the intake from this port and why do people put a filter inline to prevent this?

 

[esoteric]

Under boost the pressure in the VC blows air through the pipes into the intake, this is easily solved by getting a recirculated catch can. Unless you run a GM MAS you should keep it circulated.

 

[mnetwork]

Well at idle I can feel some air come out of that port, what is going on then?

 

[esoteric]

Well at idle I can feel some air come out of that port, what is going on then?

Your PCV is closed at idle I think, not 100% sure but its normal for air to come out of there just get a catch can and keep it circulated.

 

[mnetwork]

Your PCV is closed at idle I think, not 100% sure but its normal for air to come out of there just get a catch can and keep it circulated.

I also forgot to add that when I am feeling air come out, I also have the PCV unhooked as well.

 

[XiKeiyaZI]

@__@ It's simple function is mentioned in the above link.

Just make sure the Check Valve at the back of the Valve Cover only allows air in one way, and that should be towards the Intake Manifold so that pressure in the Valve Cover can be released into the Intake Manifold.

The Breather on the side of the VC sucks in air at idle, and pushes air out at elevated RPMs.

 

[Calan]

Lot's of confusion and misinformation in this thread guys. The valve cover vent and PCV valve work together as part of a bi-directional ventilation and pressure relief system.

You really should read the article that Bane3d linked to: http://www.dsmtuners.com/forums/articles-engine-fuel/366890-4g63t-pcv-system.html

 

[mnetwork]

What is the expected result if you had the PCV vented (not connected to intake manifold) and you were idling with the valve cover port vented. Would you expect some air to blow out?

 

[knochgoon24]

Air goes both in and out of that port. Under vacuum, air is sucked in through the side port then into the IM through the PCV valve. Under boost, blowby (inevitable) is vented out that same port and into your intake. Under optimal conditions, this blowby wouldn't contain any oil in it, but it does. So that's why people put a catch can inline with it.

 

[XiKeiyaZI]

If you left the PCV that runs to the intake manifold open..

1 : If the port on the Intake Manifold isn't plugged.. you'll have a decent sized Vaccum leak/Boost Leak
2 : You're venting metered air to the atmosphere.

Period. It'll hurt performance.

 

[mnetwork]

If you left the PCV that runs to the intake manifold open..

1 : If the port on the Intake Manifold isn't plugged.. you'll have a decent sized Vaccum leak/Boost Leak
2 : You're venting metered air to the atmosphere.

Period. It'll hurt performance.

If the PCV was left vented, the port in the manifold was plugged, and the side VC port was vented, would you expect some air to come out of the port on side since you no longer have the vacuum from the PCV?? That is my question.

 

[Calan]

If the PCV was left vented, the port in the manifold was plugged, and the side VC port was vented, would you expect some air to come out of the port on side since you no longer have the vacuum from the PCV?? That is my question.

I wouldn't expect anything in particular, other than a shorter oil life span, a film of oil in the engine bay, and maybe slightly skewed fuel trims. Any air flowing into or out of the ports would be totally dependent on your engine's blowby, and would vary from car to car.

Hook your PCV system up the proper way and call it a day.

 

[m_0ney_pit]

calan does that check valve you found have a lifetime when it gets soaked with oil? I was looking at mcmaster.com for something close to what you found but with a ball design like the OEM pcv valve and found this.

7775K61
Brass Spring-Loaded Piston Check Valve 1/8" NPTF Dryseal Male Conn, Fluoroelastomer Seat
In stock at $11.97 Each

what do you think?

 

[Calan]

I can't take the credit for finding it (I think it was Romeen maybe?), but they are pretty much indestuctible from what I have seen. I've had the same one on my car for 3 years now, and it's still in perfect condition. I haven't heard of a single failure of them either.

In fact, I run one on my fuel tank vent and now my brake booster line. If you just like spending more money, go for it. But IMHO the $1.50 Kynar valves are the next best thing since 10mm sockets.

EDIT:

Yep...For you history buffs, the first mention of the US Plastics valve IIRC was by Romeen in 1/15/07, in this post.

 

[my98gsx]

get rid of that mini filter... all that does is makes a mess inside your engine bay. Get yourself a cheep catch can. ( & yes it blows out, not in )

 

[romeen]

I can't take the credit for finding it (I think it was Romeen maybe?), but they are pretty much indestuctible from what I have seen. I've had the same one on my car for 3 years now, and it's still in perfect condition. I haven't heard of a single failure of them either.

In fact, I run one on my fuel tank vent and now my brake booster line. If you just like spending more money, go for it. But IMHO the $1.50 Kynar valves are the next best thing since 10mm sockets.

EDIT:

Yep...For you history buffs, the first mention of the US Plastics valve IIRC was by Romeen in 1/15/07, in this post.

Thanks for the recognition Craig. I can't believe how popular that check valve has become. I've seen it mentioned on several other (non-DSM) car forums. Even several guys from Europe are now using it. The dates of these posts are all after mine so AFAIK it's my baby.


OP, Craig (calan) and Wes (knochgoon24) have it right. Air moves in both directions through that fitting depending on whether the motor is under vacuum or boost.

calan does that check valve you found have a lifetime when it gets soaked with oil? I was looking at mcmaster.com for something close to what you found but with a ball design like the OEM pcv valve and found this.

7775K61
Brass Spring-Loaded Piston Check Valve 1/8" NPTF Dryseal Male Conn, Fluoroelastomer Seat
In stock at $11.97 Each

what do you think?

I'm still using the same one that I installed back in 2006 and it's still working perfectly. It's cheap and it's proven.