PCV Valve Delete and oil catch can - the great debate

[Joffe]

So i have a very low milage B9 S4 6.6k and we all know of the PCV Valve failure consequences on our engines, especially when tuned and under higher boost.
I’ve already bought but havent nstalled this

https://www.uspmotorsports.com/Racin...kaAsdSEALw_wcB

The pros, Besides removing the possibility of the PCV Valve eventualy causing positive crank case pressure and engine damage and providing a new oil cap which has positive engagement, i also am concerned about the direct injection and oil mist diluted with ethanol making its way onto my valves and baking on.
Which the catch can should solve.

The con is that the pcv valve always keeps a high negative pressure in the crank even when not under boost theough the reroute from the turbo inlet to the intake manifold. This solution plugs the intake manifold component.

My thought is that even when not under boost the turbo inket will never be under positive pressure and always allow the crankcase to vent, even if not assisted by the higher negative pressure when the compressor is fully spooled, so this is a non issue …. On older cars they just used to vent to atmosphere with or without a filter so should be fine.

Wondering if there are any strong opinions one way or the other out there

[East_Coast_S4]

So i have a very low milage B9 S4 6.6k and we all know of the PCV Valve failure consequences on our engines, especially when tuned and under higher boost.
I’ve already bought but havent nstalled this

https://www.uspmotorsports.com/Racin...kaAsdSEALw_wcB

The pros, Besides removing the possibility of the PCV Valve eventualy causing positive crank case pressure and engine damage and providing a new oil cap which has positive engagement, i also am concerned about the direct injection and oil mist diluted with ethanol making its way onto my valves and baking on.
Which the catch can should solve.

The con is that the pcv valve always keeps a high negative pressure in the crank even when not under boost theough the reroute from the turbo inlet to the intake manifold. This solution plugs the intake manifold component.

My thought is that even when not under boost the turbo inket will never be under positive pressure and always allow the crankcase to vent, even if not assisted by the higher negative pressure when the compressor is fully spooled, so this is a non issue …. On older cars they just used to vent to atmosphere with or without a filter so should be fine.

Wondering if there are any strong opinions one way or the other out there

I am discussing with them directly now as this definitely causes issues. Under stock pressure it seemed fine, running TTE710 I got excessive oil throughout my intake system and inlet and then when I changed to TTE810 running high boost it was enough to actually burn the oil and cause clouds of blue smoke at idle.

I had to switch back to stock pcv and all issues went away.

There is no check valve - as you said negative pressure makes sense its almost like my turbo inlet was sucking the oil up out of the catch can.

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[S4James]

They eliminated the flow restrictor valve? That seems stupid for exactly those reasons.

[Joffe]

Is there a breather valve setup I can rig after a catch can ?

[thermobryan]

It's not a flow restrictor valve, it's a check valve. That was put in place when it's changing from vacuum pressure (in charge pipes) to boost pressure.

I understand the theory, you don't want the heads to see excess pressure and the pcv is designed for that.

I've had the Racingline Catch Can installed for about 1000 miles now with no issues. I'm running over 30 psi boost.

It does catch the oil in the catch can, unlike the Mishimoto which gave me CEL issues and didn't catch much blow by.

My only complaint is that the dipstick for the CC hits the strut bar and you have to completely remove the can to drain it. Its not that hard, but its just a design flaw.

[East_Coast_S4]

It's not a flow restrictor valve, it's a check valve. That was put in place when it's changing from vacuum pressure (in charge pipes) to boost pressure.

I understand the theory, you don't want the heads to see excess pressure and the pcv is designed for that.

I've had the Racingline Catch Can installed for about 1000 miles now with no issues. I'm running over 30 psi boost.

It does catch the oil in the catch can, unlike the Mishimoto which gave me CEL issues and didn't catch much blow by.

My only complaint is that the dipstick for the CC hits the strut bar and you have to completely remove the can to drain it. Its not that hard, but its just a design flaw.

As soon as I swapped to the 810 I got this much oil in the inlet in just one drive.
Blue smoke on idle after stop/ start
IMG_20230415_154804.jpg

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[Joffe]

It's not a flow restrictor valve, it's a check valve. That was put in place when it's changing from vacuum pressure (in charge pipes) to boost pressure.

I understand the theory, you don't want the heads to see excess pressure and the pcv is designed for that.

I've had the Racingline Catch Can installed for about 1000 miles now with no issues. I'm running over 30 psi boost.

It does catch the oil in the catch can, unlike the Mishimoto which gave me CEL issues and didn't catch much blow by.

My only complaint is that the dipstick for the CC hits the strut bar and you have to completely remove the can to drain it. Its not that hard, but its just a design flaw.

Im glad your theory is up to spec. I think mine is but not sure … this is my understabding : the pcv valve itself in a stock setup vents positive pressure in the crank case but also regulates the level of vaccum applied to the crank case. Seperately this feeds to the line that meets the checkvalve which when not under boost, due to negative pressure in the upper intake, is the source of the vaccum. When under boost the upper intake mnaifold pressure turns positive which closes the check valve and the source of the vaccum is soley driven off o fthe turbo inlet which provides a high and variable amount of negative pressure ( in contrast to after the turbo, intercooler intake manifold which is under high positive pressure.

Again what my understanding is, is that by deleting the pcv valve, you gain the more secure oil cap but lose the negative pressure regulation and the high negative pressures of the turbo inlet can be enough to apply to much of a vaccum and suck an excessive amount of oil/fuel/water condensation back into the turbo inlet eventually gunking up the valves which because of direct injection never get cleaned.

I want to solve for the not fully engaged oil cap and possibility of the check valve failing causing catostrophic positive pressure in the crank case. But dont want to introduce contaminants into my intake. If the negative pressure was regulated the catch can would function properly and the contaminents would be minimal.

Thats my concern … if my understabding is off here please correct me. I have the racingline kit in the next room just hesitant to pull the trigger. Dont know what my current boost levels are but i’m fully hardware modded to go to 034 Stage 2+ E85 but sitting at 1+ for now. At 30 psi thats about 2 bars which is just over stock limits but with a 4 bar MAP and a hybrid turbo/tune it sounds like this can become a problem.

Thats why I was thinking why not go to an open system after the catch can . No more vaccum but solves all problems with crank case pressure except for maybe quicker oil contamination with water and fuel

[S4James]

you have the same understanding as me... there is no regulator that i can see on the the inlet line. And what is the purpose of two lines from the valve cover? More flow? Packaging constraints?

[thermobryan]

Im glad your theory is up to spec. I think mine is but not sure … this is my understabding : the pcv valve itself in a stock setup vents positive pressure in the crank case but also regulates the level of vaccum applied to the crank case. Seperately this feeds to the line that meets the checkvalve which when not under boost, due to negative pressure in the upper intake, is the source of the vaccum. When under boost the upper intake mnaifold pressure turns positive which closes the check valve and the source of the vaccum is soley driven off o fthe turbo inlet which provides a high and variable amount of negative pressure ( in contrast to after the turbo, intercooler intake manifold which is under high positive pressure.

Again what my understanding is, is that by deleting the pcv valve, you gain the more secure oil cap but lose the negative pressure regulation and the high negative pressures of the turbo inlet can be enough to apply to much of a vaccum and suck an excessive amount of oil/fuel/water condensation back into the turbo inlet eventually gunking up the valves which because of direct injection never get cleaned.

I want to solve for the not fully engaged oil cap and possibility of the check valve failing causing catostrophic positive pressure in the crank case. But dont want to introduce contaminants into my intake. If the negative pressure was regulated the catch can would function properly and the contaminents would be minimal.

Thats my concern … if my understabding is off here please correct me. I have the racingline kit in the next room just hesitant to pull the trigger. Dont know what my current boost levels are but i’m fully hardware modded to go to 034 Stage 2+ E85 but sitting at 1+ for now. At 30 psi thats about 2 bars which is just over stock limits but with a 4 bar MAP and a hybrid turbo/tune it sounds like this can become a problem.

Thats why I was thinking why not go to an open system after the catch can . No more vaccum but solves all problems with crank case pressure except for maybe quicker oil contamination with water and fuel

Good video from 034 on the issue.

I'm on Stage 3 right now running 4 bar map sensors. I'm going to install a data logger soon and I'll see the actual boost level, probably around 32psi.

I see what you're saying on negative pressure from the turbo inlet, I'll take it off and check and see how much oil is in there. My guess is probably none, there are baffles on the actual billet piece after leaving the head and more baffles on the actual catch can.

[thermobryan]

you have the same understanding as me... there is no regulator that i can see on the the inlet line. And what is the purpose of two lines from the valve cover? More flow? Packaging constraints?

PCV one is for vacuum, one is for boost.

[Joffe]

Good video from 034 on the issue.

I'm on Stage 3 right now running 4 bar map sensors. I'm going to install a data logger soon and I'll see the actual boost level, probably around 32psi.

I see what you're saying on negative pressure from the turbo inlet, I'll take it off and check and see how much oil is in there. My guess is probably none, there are baffles on the actual billet piece after leaving the head and more baffles on the actual catch can.

I was thinking I could design and 3d print an insert to the breather hose out of the catch can that slightly restricts the vacuum, let me know if you find anything in your inlet

[S4James]

PCV one is for vacuum, one is for boost.

not in the case of the racing line catch can setup its not.

[Joffe]

not in the case of the racing line catch can setup its not.

Right, your not refering to the stock hosing but the 2 braided lines from the valve cover, my guess is there are 2 different banks for each set of cylinders ? Dont know. On racingline site they then call them internally baffled turrets which do some oil seperation then feed to catchcan with single tube to turbo inlet to replace the check valve setup

[thermobryan]

not in the case of the racing line catch can setup its not.

For that one, it's for each side of the engine. Left bank, right bank.

[thermobryan]

Right, your not refering to the stock hosing but the 2 braided lines from the valve cover, my guess is there are 2 different banks for each set of cylinders ? Dont know. On racingline site they then call them internally baffled turrets which do some oil seperation then feed to catchcan with single tube to turbo inlet to replace the check valve setup

Correct. The billet piece on the head has baffles in it, then the Catch Can has baffles in it. The air flow just goes back and forth through the catch can.

[S4James]

is there something allowing the venting from the other cylinder head like a crossover tube? Im not super familiar with the internals of this motor, just curious.

[thermobryan]

For that one, it's for each side of the engine. Left bank, right bank.

Correction, its just in the middle of the block. See page 20 of this document. This very clearly explains the PCV system.

https://www.yumpu.com/en/document/re...ssp655-wg-en/2

[S4James]

do you suppose the racingline has integrated pressure control valves in each of those two stacks?

[East_Coast_S4]

do you suppose the racingline has integrated pressure control valves in each of those two stacks?

No, it's just baffled... under boost my system is fine under vacuum I'm filling the parking lot with blue smoke

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[thermobryan]

No, it's just baffled... under boost my system is fine under vacuum I'm filling the parking lot with blue smoke

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Mine doesn't. Maybe there's another issue at hand. I had that issue when I blew my turbo.

[East_Coast_S4]

Mine doesn't. Maybe there's another issue at hand. I had that issue when I blew my turbo.

The Turbo was literally installed for 2 days brand new at that point and swapping back to stock pcv resolved it completely.

It didn't smoke on the 710 but while swapping to 810 there was oil in the inlet, pipe, turbo, and charge pipes from it.

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[Esmin23]

Mine also doesn't smoke. Emptied out the can for the first time since installed, exactly 3 months ago. Maybe 2000 miles. I'm amazed at the amount of oil/water/everything else that was in there.

I did notice some of it in the turbo inlet bung. I was hoping I wouldn't see any. Should it be completely clean?

Racingline catch can

Racingline catch can

[East_Coast_S4]

Mine also doesn't smoke. Emptied out the can for the first time since installed, exactly 3 months ago. Maybe 2000 miles. I'm amazed at the amount of oil/water/everything else that was in there.

I did notice some of it in the turbo inlet bung. I was hoping I wouldn't see any. Should it be completely clean?

Racingline catch can

Racingline catch can

Yea after maybe 1500 miles I had a few Oz of oil doesn't even seem watered down... that's a lot.

Stock system at least recirculates it

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[Joffe]

Mine also doesn't smoke. Emptied out the can for the first time since installed, exactly 3 months ago. Maybe 2000 miles. I'm amazed at the amount of oil/water/everything else that was in there.

I did notice some of it in the turbo inlet bung. I was hoping I wouldn't see any. Should it be completely clean?

Racingline catch can

Racingline catch can

In an ideal world but the whole point of the closed loop is that unburnt fuel vapor and oil goes back tothe engine ti be burnt, even in the stock setup ….

In relity as long as its minimal should be fine as it has the turbo then intercooler then intake manifold to go through, its actually better than dumping directly into the intake manifold as the valves are never cleaned whether running e85 or 91/91, because the ea839 is directinection


Im going to install mine next week, I might add a little steel wool to the catch can to help increase conensation i. The catch can. Also looking if there are any vaccum valves I can add so under high boost it doesnt go to crazy with the vaccum

- - - Updated - - -

Any pick of the turbo i let ?

[Esmin23]

Yea after maybe 1500 miles I had a few Oz of oil doesn't even seem watered down... that's a lot.

Stock system at least recirculates it

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I poured it into a clear bottle where it separated. About 1/4 of it was water. The rest was oily sludge. I haven't noticed any oil loss on the dipstick or MMI reading.

Is the vac that strong that it sucked it out of can at idle? Seems like such a huge engineering flaw

[Esmin23]

In an ideal world but the whole point of the closed loop is that unburnt fuel vapor and oil goes back tothe engine ti be burnt, even in the stock setup ….

In relity as long as its minimal should be fine as it has the turbo then intercooler then intake manifold to go through, its actually better than dumping directly into the intake manifold as the valves are never cleaned whether running e85 or 91/91, because the ea839 is directinection


Im going to install mine next week, I might add a little steel wool to the catch can to help increase conensation i. The catch can. Also looking if there are any vaccum valves I can add so under high boost it doesnt go to crazy with the vaccum

- - - Updated - - -

Any pick of the turbo i let ?

I'm assuming the vapor carries some oil remnants into the inlet. It was the same color as the stuff in the can. It wasn't dripping or heavily accumulated. Unfortunately no pic. But I'll be cleaning it more often. I wonder if some type of filter can be used to prevent it from getting to the inlet? Let me know how it goes for you

[AldermanToffee]

I don't believe the RacingLine catch can kit comes with it, but it's quite common to place steel wool inside the catch can.

[flee]

I may remove mine today and take a look. As it bothers me not having a drain as every other can I’ve owned…


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[kmarei]

I may remove mine today and take a look. As it bothers me not having a drain as every other can I’ve owned…


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it bothers me that ANY oil could potentially make its way to the combustion chamber
isn't this what causes carbon build up on our valves?

[thermobryan]

I may remove mine today and take a look. As it bothers me not having a drain as every other can I’ve owned…


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Yeah, same. This was their response to my email of how to clean/drain. I was thinking of just drilling in a section where I could suction out the oil if needed.


"This needs to be removed opened and emptied, this is also a good time to clean the unit out if required."

[imadad2]

My 2018 S4 just arrived and drove it some, but nothing WOT yet. I noticed some oily residue on the side of the engine on some of the hoses and I think a sensor. Not sure if it was just spill over from a previous fill and person being too lazy to clean or if its the start of the PCV issue myself. I plan to remove the engine cover and clean everything to see if its leaking. Also maybe pull the hoses off to see if the check valve is bad. Ultimately, I love the look (not the price) of the RacingLine, so will be looking into that.

[Joffe]

Weighed cost benifit took the plunge,,

I cut 3 layers of 1/8” thick steel wool sheet and placed ontop of baffles on crankcase side of the catchcan
Will help conense more vapor and get pulled into the baffles no risk of getting sucked8nt9 the inlet.

I also installed the 034 superduper inlet with x34 intake adapter which is like an inch thicker than stock.
While remoing the stock inlet there was a little ethanol oil vondensation which is ultimately what the closed loop pcv system is designed to do.

The difference is when idling, the stock checkvalve also vents this directly into the intake manifold.


Also did rear subframe inserts and called it a day … doing rear diff inserts and oil change tomorrow.

I only have 6600 miles and had an oil changed once before but i want to start from scratch and will be changing every 2k.

Want this car to last even with full bolt ons ( minus hybrid)

IMG_0015.jpgIMG_0015.jpg

[Esmin23]

Weighed cost benifit took the plunge,,

I cut 3 layers of 1/8” thick steel wool sheet and placed ontop of baffles on crankcase side of the catchcan
Will help conense more vapor and get pulled into the baffles no risk of getting sucked8nt9 the inlet.

I also installed the 034 superduper inlet with x34 intake adapter which is like an inch thicker than stock.
While remoing the stock inlet there was a little ethanol oil vondensation which is ultimately what the closed loop pcv system is designed to do.

The difference is when idling, the stock checkvalve also vents this directly into the intake manifold.


Also did rear subframe inserts and called it a day … doing rear diff inserts and oil change tomorrow.

I only have 6600 miles and had an oil changed once before but i want to start from scratch and will be changing every 2k.

Want this car to last even with full bolt ons ( minus hybrid)

IMG_0015.jpgIMG_0015.jpg

Awesome. I'll have to do the same with the steel wool. But I've just recently noticed slight oil build up on seals of the valve cover. Thought it was a valve cover leak, which would've been pretty strange, considering that I've never noticed it before, even while installing the racingline PCV.

Ends up being the new gasket I replaced while installing the billet plate to the head. I've bought another and will replace it this weekend. That will be the last shot with this thing. I'm seeing more cons than pros thus far with it.

[Joffe]

Awesome. I'll have to do the same with the steel wool. But I've just recently noticed slight oil build up on seals of the valve cover. Thought it was a valve cover leak, which would've been pretty strange, considering that I've never noticed it before, even while installing the racingline PCV.

Ends up being the new gasket I replaced while installing the billet plate to the head. I've bought another and will replace it this weekend. That will be the last shot with this thing. I'm seeing more cons than pros thus far with it.

I was really careful with that gasket and reused. Also tightened the 6 bolts in a cross hatch only a little at a time to ensure the gasket didnt move, hopefully I’ll be fine

[Esmin23]

I was really careful with that gasket and reused. Also tightened the 6 bolts in a cross hatch only a little at a time to ensure the gasket didnt move, hopefully I’ll be fine

Yeah I was very careful as well. I installed it cross hatch. But a new gasket. Maybe I should’ve used the old one lol

[GeorgeS5]

Hi all,

I recieved the updated catch an for the B9, oil cap is different and there's a drain on the bottom


IMG_20230529_091019.jpgIMG_20230529_091025.jpg

[imadad2]

Hi all,

I recieved the updated catch an for the B9, oil cap is different and there's a drain on the bottom


IMG_20230529_091019.jpgIMG_20230529_091025.jpg

Did you just recently purchase it? The OP stated the catch can didnt have one, so wondering if they have updated it since then.

[GeorgeS5]

Did you just recently purchase it? The OP stated the catch can didnt have one, so wondering if they have updated it since then.

Yes i have one of the first revision models, incl the drain and upgraded oil cap

[Esmin23]

Hi all,

I recieved the updated catch an for the B9, oil cap is different and there's a drain on the bottom


IMG_20230529_091019.jpgIMG_20230529_091025.jpg

That’s awesome! Yet disappointing for those who already have it. Ridiculous that the revision happened so soon. They advertise as the “the last PCV system you’ll ever buy”. Apparently not, and based on that slogan, alone, I’ll be getting in touch with them to replace with the new revised parts

[imadad2]

Yes i have one of the first revision models, incl the drain and upgraded oil cap

I did see that the cost went up from a month or so ago. Saw it listed for 840-870ish, now its nearly 950.