PCV Modification and Education Thread

[CorneliusRox]

What is the PCV?
The Positive Crankcase Ventilation (PCV) system is used to pull oil vapor and blowby out of the crankcase/valve cover and keep the engine internals cleaner.

How does the PCV work?
The PCV works two ways:
1) [During Vacuum] Vapors are sucked from the valve cover through a one way check valve, through a tube, and into the intake manifold. The engines natural vacuum is used to suck the vapors in while it is sucking in air for combustion.


2) [During Boost] Vapors are sucked from the valve cover through a one way check valve, through a tube (known as the rear PCV), and into the turbo just before the charge air (boost). The turbo spooling will create a vacuum.




What fails on a PCV?
Almost always when a PCV fails, it is the one way check valve between the valve cover and the intake manifold. This allows the boosted air to be pushed into the valve cover, and can blow out seals and spray oil in your engine bay while making you lose boost.

What is bad about a PCV like this?
1) The fail. Obvious.
2) It leaves a lot of carbon buildup on your valves. It is true that a Direct Injection car will get carbon buildup slightly just by the pulses and valve timing, but the reason it is an issue on these cars is because of the PCV.
3) It leaves a pool of oil in the intercoolers which reduces their efficiency.

My Quick Solution
Removing the tube from the valve cover to the intake manifold and use these plugs to seal the holes. This will still allow oil in the intercoolers and even carbon on the valves (slightly less), but if your PCV failed, or you just want to make it so it cannot ever fail. This is a quick solution.

Find two plugs (3/4” OD), washers, and bolts like these. They can be found at an Ace Hardware, or Do It Best Hardware in the bolt section.

Then after removing the tube, install:


You are now bullet proof in regards to your PCV. All that for $5. Not bad.

NOTE: Some people may have a check valve in the 'rear PCV' tube that will make a clicking noise. Be sure to remove the check valve or to puncture it (if puncturing, make you you safely remove anything that could potentially fall into the turbo, that is BAD).

My Full Solution
This involves using one of the plugs from before to plug the intake manifold. You also need some 3/8” fuel line tubing (it works great for the heat and oil/blowby junk) (5ft was $6), a plate to cover the PCV area on the valve cover with one hole ($20), a T-fitting ($1), Two MPT fitting to barb hose 3/8” ($2), some hose clamps ($2.50), and a bit of sheet metal ($5).
First, we need to cover the tube that goes back to the turbo (rear PCV). Take your tube off and cut your sheet metal to match it like a gasket but with no hole so that when you tighten it down, there is a seal.

Second, remove the tubes and install your plate on the valve cover that replaces the PCV.
Now carefully route your line coming from the oil separator (furthest plug from the front of the engine) out so it is free on the side.
Install the first MPT fitting into the PCV plate. Install the second into the oil separator tube (use Teflon tape in order to make a seal. This is not a high pressure line).
Now you are almost done, take your line and route the hose down from the valve cover PCV plate, tie in the T-fitting so that you can route hose from your oil separator tube to the tee, then continue routing hose down, and finish up with zip ties to hold everything in place. Your end results should look like this:





NOTE: I eventually removed my cone air filter on the end of the vent line because it created too much back-pressure after getting saturated with oil.

This solution will keep oil out of your intercoolers, almost completely cure you of carbon buildup, and be completely robust in worry free. I have been running this setup for about three months and checked over everything yesterday to make sure there were no issues. It has worked flawlessly.

Will this hurt my engine?
No, this is how crank cases have been vented for many many years. However, because of emissions, this was implemented, and if you think about it, it is very similar to EGR.


NOTE: I am not liable for anything you do. This is just for everyone to use as information or inspiration.
Criticism Appreciated.

Enjoy


Some credit due to Shane for some conversations we had back and forth! Thanks again.

[Hugh@EuropaParts]

Hey Corey... I love your use of primary colors in the first 2 pics

[LoKisSpYdR]

So it's like a catch can without the can...Where does the gunk go?

P.S. Also, like the use of color to show air flow temp. Very nice.

[CorneliusRox]

Hey Corey... I love your use of primary colors in the first 2 pics

Why thank you Hugh.

So it's like a catch can without the can...Where does the gunk go?

P.S. Also, like the use of color to show air flow temp. Very nice.

ha ha air flow temp is so important!
idk I dont like catch cans because you have to empty them. This vents to air. You'd be surprised at how much of this is moisture, then some is oil vapor (which stays in the engine more since there isnt a vacuum) and some is blowby (which is what you see leaving mostly other than moisture). All in all, your oil will get very slightly dirtier, but as long as you do oil changes every 8000-10000 miles, you wont even notice a thing. And most of use would have to put a few quarts in to make it that far anyways.

[p1nk50ck]

i hate that pictures are blocked here at work :-/

I'll have to look into this, since i'm still on my stock PCV, and i'd like to get this situation taken care of before it becomes a problem.

Thanks for the writeup!

[LoKisSpYdR]

So you just replace the "crappy small cone filter" every oil change or so and you're good?

[Quattro]

interesting solution you have came up with. I did the PCV delete and I don't like the smell of the burnt oil (according to my friends). How bad is the oil smell since it is evaporation to the air?

-randy

[Hugh@EuropaParts]

I run a catch can and I can tell you that when sitting in traffic or at a light with the windows open you CAN smell it...

interesting solution you have came up with. I did the PCV delete and I don't like the smell of the burnt oil (according to my friends). How bad is the oil smell since it is evaporation to the air?

-randy

[Quattro]

I run a catch can and I can tell you that when sitting in traffic or at a light with the windows open you CAN smell it...

yuck! I was going to use my catch can so I didn't smell the oil....From what it appears, regardless of what method I use besides stock I will be able to smell lovely burnt oil?

[Rodmar]

I just dont put oil in my car.....issue fixed

[CorneliusRox]

So you just replace the "crappy small cone filter" every oil change or so and you're good?

Honestly, it gets a little saturated at the bottom of it, but I havent needed to switch it out. I was worried about this at first, but after taking it off and literally blowing through it (with my mouth...) it still flows freely.
When I first did this I didnt have a filter and it looked like steam was coming from under my hood.

interesting solution you have came up with. I did the PCV delete and I don't like the smell of the burnt oil (according to my friends). How bad is the oil smell since it is evaporation to the air?

-randy

Since I have added the filter, and moved the position of the outlet, I havent had an issue, at all actually. I sit in traffic a lot on the way into work, and in the morning when it is cold is when I used to be able to see it and smell it. Since changing, I havent. I've been extremely happy with the setup. Now I need to clean my valves.

[Hugh@EuropaParts]

yuck! I was going to use my catch can so I didn't smell the oil....From what it appears, regardless of what method I use besides stock I will be able to smell lovely burnt oil?

Depends on the type of catch can... vented or non vented. You will get more smell from a vented... obviously.

[p1nk50ck]

I just dont put oil in my car.....issue fixed

lol

[mec]

Great write up!

[davvinchi]

What is the PCV?
The Positive Crankcase Ventilation (PCV) system is used to pull oil vapor and blowby out of the crankcase/valve cover and keep the engine internals cleaner.

How does the PCV work?
The PCV works two ways:
1) [During Vacuum] Vapors are sucked from the valve cover through a one way check valve, through a tube, and into the intake manifold. The engines natural vacuum is used to suck the vapors in while it is sucking in air for combustion.


2) [During Boost] Vapors are sucked from the valve cover through a one way check valve, through a tube (known as the rear PCV), and into the turbo just before the charge air (boost). The turbo spooling will create a vacuum.


What fails on a PCV?
Almost always when a PCV fails, it is the one way check valve between the valve cover and the intake manifold. This allows the boosted air to be pushed into the valve cover, and can blow out seals and spray oil in your engine bay while making you lose boost.

You missed something: The PCV also allows air to flow from the intake preboost side to the intake manifold by passing the turbo and intercooler. The pressure bladder in the PCV only lets a little air by under idle(high vacuum) and lets as much air as can flow through the tube by under lower vacuum(1000rpm up till boost is achieved) This lets you have low end power that you would otherwise cut off by doing the pcv delete. Take a look at the pre-boost check valve and you will see there is a small air flow hole to bypass the check valve. The vacuum air flow is still limited by the check valve for the pre-boost intake side. Ideally a robust check valve that wouldn't fail could be installed in-line with the PCV to solve all issues and keep the benefits of the PCV.

You also miss represent the PCV system a little: the PCV is not for keeping the engine internals cleaner, but rather for keeping oil in the engine and not on the engine, ground, roadway, etc. The stock setup however I will agree doesn't properly separate the oil from the blowby gases before feeding them into the combustion chamber and preturbo air flow. I was running a catch-can with t-split on it, venting without a check valve to the pre-boost airflow, and putting a check valve and pcv valve inline to the intake manifold and it worked really well. The oil was being kept in the system with the 034 catchcan drain too. The only problem was when I showed wifey what a great thing she had been running under the hood for a few months, she freaked out cause the parts didn't look like they "belonged", and it is her car, so I bought another PCV and we are back to adding a quart every 2000 miles again without the catchcan.

[CorneliusRox]

You missed something: The PCV also allows air to flow from the intake preboost side to the intake manifold by passing the turbo and intercooler. The pressure bladder in the PCV only lets a little air by under idle(high vacuum) and lets as much air as can flow through the tube by under lower vacuum(1000rpm up till boost is achieved) This lets you have low end power that you would otherwise cut off by doing the pcv delete. Take a look at the pre-boost check valve and you will see there is a small air flow hole to bypass the check valve. The vacuum air flow is still limited by the check valve for the pre-boost intake side. Ideally a robust check valve that wouldn't fail could be installed in-line with the PCV to solve all issues and keep the benefits of the PCV.

You also miss represent the PCV system a little: the PCV is not for keeping the engine internals cleaner, but rather for keeping oil in the engine and not on the engine, ground, roadway, etc. The stock setup however I will agree doesn't properly separate the oil from the blowby gases before feeding them into the combustion chamber and preturbo air flow. I was running a catch-can with t-split on it, venting without a check valve to the pre-boost airflow, and putting a check valve and pcv valve inline to the intake manifold and it worked really well. The oil was being kept in the system with the 034 catchcan drain too. The only problem was when I showed wifey what a great thing she had been running under the hood for a few months, she freaked out cause the parts didn't look like they "belonged", and it is her car, so I bought another PCV and we are back to adding a quart every 2000 miles again without the catchcan.

I dont think the intercooler routing is restrictive enough to let the air vented through the rear pcv->vc->intake manifold to create any extra power, and I didnt feel any difference at all in low end power. The reason I actually edited the first picture (if you look close, I had another arrow as you said) was because I found that there were two rear pcv tubes and one had a complete check valve and the other had something, I assume, like what you are talking about with a check valve with a hole.

Sorry if I didnt make it clear enough, but that is what I meant when I said they made the PCV because of emissions. It is to take out blowby and also to funnel all that stuff through the engine, burn it again and then out the exhaust. That is why I compared it to an EGR because they really are very similar. Egr takes the after effect of the combustion chamber and throws it back through again, and the PCV does as well just it is blowby and not from the exhaust.

I also agree that running two catch cans can pretty much do all this as well, but then you have to buy/make two catch cans, and empty them every so often, and if you dont and one fills then freezes, goodbye seals. This is obviously if someone lacks the maintenance, but it is something I just prefer not to have to deal with.
That being said, my truck is routed this way and I have never had a drop of oil on the driveway because of it. It may do a little while driving?

If you think that the pre-boost extra vent really does give more low end power, I would be more than happy to make a vent post-MAF into the intake manifold with a check valve. I just dont think that would be the case though, and would take control away from the throttle body.

[davvinchi]

"If you think that the pre-boost extra vent really does give more low end power, I would be more than happy to make a vent post-MAF into the intake manifold with a check valve. I just dont think that would be the case though, and would take control away from the throttle body. "

Yes I do think you get more pre-boosted/aspirated power with my proposed (and tested but not proven) setup.
However: It only works if you have a PCV valve and a check valve, otherwise the air is uncontrolled under idle and you will end up with erratic idle.


NOTE:The stock intake side(left side of pic) check valve was not present in my setup when I tested since I have a early model, so if you have that stock check valve I don't know what the result would be.

If you have a classic spring loaded PCV valve under high vacuum the vacuum pulls the valve partially closed, when you open up the throttle body, vacuum is lessened and the spring opens the air flow, under boost the check valve stops airflow so boost is not lost. So with a PCV and a check valve the throttle maintains full control.
Ever since my successful experiment in PCV catch can routing I have been looking (in vain?) for a spring loaded PCV valve that also acts as a check valve that I could install inline with my branched hose from the catch can to the Intake Manifold.

DISCLAIMER:
Just be aware that I am not responsible for anything you do to your car and whether or not it makes added low end power to me is simple dynamics, but Until someone dyno's my setup there is no firm proof that I'm right.

[airbornerifleman]

yuck! I was going to use my catch can so I didn't smell the oil....From what it appears, regardless of what method I use besides stock I will be able to smell lovely burnt oil?

Correct

[CorneliusRox]

So is this a more clear version of your picture?


So with the stock check valve in the rear pcv, there couldnt be air flow because it only allows it out. So potentially, you could be right and I never experienced any difference because I had the stock rear pcv with the check valve in it. If that is the case, then earlier 2.0TFSI engines should all have more low end than all the others. I have driven a couple earlier models, and I dont know if they did or didnt have the check valve, but I never felt a difference.

Tell your GF to let you go mess with her car a bit under the hood and take some videos both ways.

"If you think that the pre-boost extra vent really does give more low end power, I would be more than happy to make a vent post-MAF into the intake manifold with a check valve. I just dont think that would be the case though, and would take control away from the throttle body. "

Yes I do think you get more pre-boosted/aspirated power with my proposed (and tested but not proven) setup.
However: It only works if you have a PCV valve and a check valve, otherwise the air is uncontrolled under idle and you will end up with erratic idle.


NOTE:The stock intake side(left side of pic) check valve was not present in my setup when I tested since I have a early model, so if you have that stock check valve I don't know what the result would be.

If you have a classic spring loaded PCV valve under high vacuum the vacuum pulls the valve partially closed, when you open up the throttle body, vacuum is lessened and the spring opens the air flow, under boost the check valve stops airflow so boost is not lost. So with a PCV and a check valve the throttle maintains full control.
Ever since my successful experiment in PCV catch can routing I have been looking (in vain?) for a spring loaded PCV valve that also acts as a check valve that I could install inline with my branched hose from the catch can to the Intake Manifold.

DISCLAIMER:
Just be aware that I am not responsible for anything you do to your car and whether or not it makes added low end power to me is simple dynamics, but Until someone dyno's my setup there is no firm proof that I'm right.

[camoto]

It would be cool to see one of the manufacturers pick up this "new" routing and release a kit with all of the needed parts.

[Flexcj5]

Last monday started with weird audi issues involving lots of oil under the hood, misfires and a flashing CEL. Park the car and begin tearing into her and find a trashed crankcase pcv hose.


I am sick of oil in the intercoolers and intake, sick of our overly complicated pcv system so I ordered an IE valvecover and am tearing the car all apart. Here's my plan but have a few questions. I want to run the large hose off the crankcase to my catch can with breather (pic below) and tee into it with the new hose off the vc. I've already blocked off the rear pcv on the turbo but I'm not sure where to go with the small hose (2nd pic). Thoughts? What else am I missing here?



Also did carbon cleaning and 145 prv while I had the intake off.

[CorneliusRox]

I would leave the small hose, and I would tee together the hose from the oil separator and the hose from the VC before the catch can, and then the catch can vent to air with a filter like you have it.

[DRAKLORE]

Flex that would be similar to my setup..

[Flexcj5]

So we're thinking just leave the small hose on the turbo vented to atmosphere with a filter or should i tee it in to the rest of my reroute?

[DRAKLORE]

Well my small hose is vented to atmosphere

[DRAKLORE]

No filter, just hangs down

[Flexcj5]

No filter, just hangs down

I'm talking about the small hose that runs from the turbo to the vc next to the rear pcv. I think youre talking about the small hose running up from the intake side. Factory k03 parts.

[Flexcj5]

Hose im referring to:

[CorneliusRox]

Unless you are switching to a turbo that doesnt have the port for it, I would just leave it.

[keepsix]

Very informative! This should be updated in the "New Members 2.0" sticky!

[DRAKLORE]

Unless you are switching to a turbo that doesnt have the port for it, I would just leave it.

X2 I agree

The majority of oil vapor goes through the larger hose

[Robo623]

so going off of this image and what i can make out from your other pictures your basically saying remove hose from valve cover to manifold block both holes then block pcv rear then run hose from turbo to check valve with t fitting in between with hose and filter to take care of gunk ?

[CorneliusRox]

so going off of this image and what i can make out from your other pictures your basically saying remove hose from valve cover to manifold block both holes then block pcv rear then run hose from turbo to check valve with t fitting in between with hose and filter to take care of gunk ?

not exactly. Everything is right except for this part:

then run hose from turbo to check valve with t fitting in between with hose and filter

You block off the rear PCV to the turbo, then you have a line coming out of the front PCV (the plastic thing that holds the tube for the oil separator and intake manifold), and vent that to air with the oil separator line Teed in. If you dont want to buy a fancy bracket like me, you can gut out the stock PCV. Basically by destroying the check valve. Or you can find some that is broken already (which means the check valve is toast), but I would be slightly worried about that still having just a little too much back pressure.

[CorneliusRox]

Hose im referring to:

That is not for PCV, but for EVAP and the N80 valve

[Robo623]

read on other threads that the pcv changed in the 07 year i have an 07 so should i be looking at the same setup or did they do a change in the second half of that year ?

[CorneliusRox]

read on other threads that the pcv changed in the 07 year i have an 07 so should i be looking at the same setup or did they do a change in the second half of that year ?

I am pretty sure they just revamped the check valves. Everything on here should still apply and work the same.

[mec]

So moral of the story, cut out a tin can or piece of steel and block off the hose that goes from the turbo to the left side of the PCV(if you are looking at engine bay). The upper portion of that hose can stay unaltered. Then take the catch can hose that goes to pcv port closest to you and vent that to atmosphere?

So it would be one hose coming out of the valve cover(port closest to firewall) going right, then that attaches to the catch can, the other hose on the catch can is vented to atmosphere, the pcv port that is remaining(the closest to you) can be plugged up since nothing is going into it, and this is why you can block off the hose going to the turbo with the tin can. You would then eliminate the oil recirculation?

[CorneliusRox]

So moral of the story, cut out a tin can or piece of steel and block off the hose that goes from the turbo to the left side of the PCV(if you are looking at engine bay). The upper portion of that hose can stay unaltered. Then take the catch can hose that goes to pcv port closest to you and vent that to atmosphere?

So it would be one hose coming out of the valve cover(port closest to firewall) going right, then that attaches to the catch can, the other hose on the catch can is vented to atmosphere, the pcv port that is remaining(the closest to you) can be plugged up since nothing is going into it, and this is why you can block off the hose going to the turbo with the tin can. You would then eliminate the oil recirculation?

That's the idea. I want to eventually run my MAF like Shane, and also clean the carbon off the valves, and I dont want any oil ever giving me a problem with either of them. Plus I have a new intercooler that I need to eventually install and I dont want that getting coated in oil either.

[DRAKLORE]

I guess I'll add the pics I made for Corey a few months ago for good measure



Here if you can see in the center "use a tin can"


Some more reference

Reference


And a reference/joke lol

On the ATP setup I blocked the rear PCV

A MAF relocation:



And this is for you Billet Valve cover guys, Made this one For Hubert @ Europa:



Eventually moving from that to having the catch can dump to atmosphere






Brad-look my breather tube is "flexed" lol

[DRAKLORE]

Inside of a catch can (42DD) and the benefit!




And for those with a stock valve cover:




An what the ATP rear PCV is supposed to look