Post PCV delete question...

[buford118]

Like the title states, I deleted much of the PCV system on my 1.8T last weekend, along with upgrading my diverter valve (to a much stiffer metal DV).

Yesterday, coming off a stop sign I went WOT. When the car went to shift into 2nd (auto trans) I had a BOV sound (WHOOSH). Awesome!.... not. I don't have a BOV installed! So what happened? My engine blew the dipstick tube out of the funnel! Big mess all around...

My question is, what caused this? Obviously too much positive pressure, but from where?

Just for reference, my post-pcv setup is as follows:

3/4" from the crank breather tube T'd into 3/4" from the VC, dumping down to a 034 Billet check valve with 1/2" tube dumping under the car.

DV vacuum hooked directly to the IM.

EGR and SAI still intact.

Car is completely stock (for now) besides the PCV delete and DV.

Any thoughts?

Thanks,
Brady

[MetalMan]

My question is, what caused this? Obviously too much positive pressure, but from where?

3/4" from the crank breather tube T'd into 3/4" from the VC, dumping down to a 034 Billet check valve with 1/2" tube dumping under the car.

This is your problem. Get rid of the 034 billet check valve. That piece is intended to be used in conjunction with vacuum pulling it open. It's possible that valve's spring pressure is greater than pressure it takes to blow out your dipstick.

[buford118]

Makes sense, but this is a ball bearing type check valve.

Same answer? I was under the assumption that this check valve would flow freely out, but not allow unmetered air (or critters) to enter back through the lines.

If I don't need this check valve, great. But I installed it as a cautionary measure.

Thanks,

Brady

[old guy]

It always amazes me when peeps remove stuff from the engine with no idea as to what it does.

Here's the problem. Buford connected the lower block breather to the upper block breather and then stuck the 034 check valve on the output line backwards. Be prepared to start replacing a lot of seals and gaskets. All of you block blowby pressure is simply building up until it blows something out. You are lucky it was only your dipstick.

[MetalMan]

Makes sense, but this is a ball bearing type check valve.

Same answer? I was under the assumption that this check valve would flow freely out,

If I don't need this check valve, great. But I installed it as a cautionary measure.

Thanks,

Brady

It does have a ball bearing, yes, but there is a spring pushing on the ball to seal it off.
For the valve to be effective there needs to be enough positive crankcase pressure to overcome the spring force. And apparently that wasn't the case, as evidenced by the dipstick blowing out.

Although it could simply be time for a new dipstick with fresh O-rings

but not allow unmetered air (or critters) to enter back through the lines.

In your case, there's not really an issue with metered/unmetered air since you deleted the vacuum connections to the intake manifold and TIP.
If you're worried about bugs/critters then perhaps a wire mesh screen at the end of the 3/4" hose would work?

[MetalMan]

It always amazes me when peeps remove stuff from the engine with no idea as to what it does.

Here's the problem. Buford connected the lower block breather to the upper block breather and then stuck the 034 check valve on the output line backwards. Be prepared to start replacing a lot of seals and gaskets. All of you block blowby pressure is simply building up until it blows something out. You are lucky it was only your dipstick.

I'm no so sure he has the 034 check valve in backwards:


Sounds like the small nipple-end is oriented away from the engine, which would allow the ball to unseal if there's enough crankcase pressure to overcome the valve's spring pressure. My thoughts are, there wasn't enough crankcase pressure to make that happen.

[old guy]

Yep. You are probably right. But my original statement stands. Why remove stuff before you understand the function?

As you pointed out, how would you get un-metered air without a connection to the intake manifold?

The PCV/PRV performs a necessary function. When under vacuum the PCV purges the block. When under boost the PRV allows the TIP to actively purge the block.

Remove both and all you have left is a slightly pressurized block blowing out whatever opening you happen to provide. Definitely not a recipe for a healthy engine.

[old guy]

Brady: Eliminating the block breathing system as you have done does nothing to improve the performance of your engine. In fact, it only serves to increase sludge and build-up by not properly purging the block as you drive. I see that you live in Minnesota. Proper block purge is even more critical in cold environments. What happens is that without a decent block purge moisture can build up in the block and mix with the oil forming a frothy mess.

Here's my suggestion. Put the PCV valve back where it belongs and connect it to the intake manifold. Connect the lower block breather to the upper block breather (back of the valve cover). Then connect the valve cover back to the TIP with a PRV at either end of the connection.

Your engine will appreciate it.

[Charles.waite]

Going to go get some popcorn for this thread.

[old guy]

Going to go get some popcorn for this thread.

Nope. I'm done here. I have posted enough information on the advantages of maintaining proper block ventilation. Search and ye shall find.

[buford118]

Old guy, I appreciate your response. I wasn't deleting the system to gain performance, but rather to simplify the system. I read through the forums, I did my research. At the end of the day, I needed the car back on the road, and the configuration that I installed was (minus the check valve-thought it was a good idea at the time 😳) the most direct way of achieving that. After your input on my setup, I will be re-installing the pancake valve and configurating the system how you recommended. Again, I appreciate your input, and I thank you for sharing your wealth of experience and knowledge of these systems. We are not worthy!

Thanks,
Brady (n00b)

[Seerlah]

Spend the money on the rest of the 034 kit and put things back together. Being silicone covers issue that made the system a hassle, which was the toll taken on rubber parts in a rather compact engine bay (engine is small...but so is the space it exists in which can get quite hot). While you are at it, upgrade the braided vacuum lines with silicon ones (cheap on ebay). Should make your PCV system pretty problem free, so you can concentrate on the other frustrations Audi ownership has in store for you (not joking).

I personally removed mine with -10AN line coming from crank case and one from valve cover, dumped to under car. But...my car is also highly modified (ie will never be worth the aggravation bringing back to stock...would rather part, sell as whole, or keep). Actually want to 1/2" NPT tap valve cover for another vent. But also thinking about E Scavenging back into the exhaust. But in a nutshell, all my PCV system stayed till the day I went with a larger turbo with engine build, SAI and all.

But really, it is your car and it really does simplify things. So I understand and am def not the person to tell another what to do with their vehicle. It's yours!!! But...you should first understand what it does, what each component does, and def how to modify it properly. Or don't modify it at all. Think that may be what bothers Fletcher (Old Guy) so much on the matter. Taking a guess. My suggestion is to do it properly and at least understand the system before you try and simplify it. For example, it creates more vacuum which piston rings love and your brake booster requires for you to actually stop your car. Larger turbo guys who simplify the system by removing it completely and run aggressive camshaft profiles lower the efficiency of their braking systems tremendously (ie -12 in/hg at idle). But...a BBK is there to counteract.

[old guy]

Brady -
I apologize if I came across a bit harsh in my first response. It's just that over the years you would not believe how many threads start off with "Help! I did a PCV/Vacuum/Whatever delete and now...."

Yes, the components are prone to breaking apart over time. I have had to replace numerous components myself. but in the long run your engine will be healthier by maintaining a purge stream through the block rather than just letting the block blow-by build up and escape through an opening somewhere.

Cheers!

[Charles.waite]

Joking aside, I absolutely concur with Old Guy and Seerlah. They design the block breathing like they did for a reason and when it's setup right it works just fine and will do a great deal to combat sludge buildup and wearing it seals and gaskets.

I ran a full 034 off kit and went through my entire vacuum system and replace the check valves with Kynar valves from US Plastics and silicon hoses. I replaced the PRV pancake with a new OEM valve and the suction jet pump with a latest revision OEM one as well. I deleted nothing and retained all OEM functionality aside from the auxiliary breather port on the valve cover since the 034 breather system bypasses that.

In the 4+ years I owned my car and the 2 years the new owner has driven it, the system has been totally bulletproof. Yea the silicon breather sweats some oil residue but that's minor and mainly just a cosmetic issue. Otherwise it worked perfectly for over half a decade. Definitely longer than the OEM system given the state it was in on my 2004 when I picked it up in 2010. My car always idled perfectly and had a nice, VERY healthy vacuum throughout its time with me. I'm very much a proponent of doing this once and doing it right.

[MurkyRivers_A4]

Nope. I'm done here. I have posted enough information on the advantages of maintaining proper block ventilation. Search and ye shall find.

Uh, can I also put chocolate milk in my engine? Does this boost performance?

I was thinking also, that the turbo is somewhat restrictive and I feel that opening up that exhaust passage would make routing of the exhaust gasses so much easier. So just bypass the turbo and route the exhaust gasses straight to the intake, eliminating the restrictive turbo..... thoughts?

Diagram:

[B5carl]

I'm also wondering about excessive crank case pressure at idle or whenever the valve is open I'm guessing below 5PSI. Looking to connect a 10AN line directly to the crank case breather -> to valve cover using 10AN T -> then to non atmosphere catch can -> to intake.

From what I know the PCV delete will remove the extra or if not main vaccum source to create a higher negative crank case pressure whenever the valve is open, which will be the highest at idle which is about -15 to -25 inHg. Without the valve it's getting vacuum from the intake filter side.. but that's not nearly a good enough vaccum as it would be if it was connected directly to the intake manifold. Since it's T'd to the intake filter side it would actually be getting a little less vaccum than what it would read inside the intake manifold. The hose coming from the intake manifold looks pretty big so it must be a strong source.

Once it's completely closed it will act just like it's not there but when it's opened there will be either some pressure being pushed into the crankcase from anything over 0 PSI and closing at 5PSI(guess) and under vaccum it will be pulling crank case pressure.

From what I've seen not many people have had issues with the 3 connection method. Alot have even used atmospheric catch cans so there is practically no crank case vacuum ever.

So my main question is, what PSI does the valve completely shut closed and trying to guess how much actual vaccum the crank case is getting when the PCV is open and if it even really matters? I'm probably going to just use the 3 connection method since it's alot more simple to set up.

[B5carl]

Basically all the crank case fumes will need to be filtered through the catch can or over time will cause a build up of greasy moisture inside the turbo, intercooler core, piping, and throttle body since it's getting sent directly to the turbo inlet and not bypassing directly to the intake manifold. The MAP and IAT sensors might also be affected.

So I want some feedback on the condition of the turbo inlet, intercooler core, and throttle body Venturi from the guys who have done this mod. My main concern is intercooler because I would have no way in knowing how clean it actually is over time without removing it every so often. Actually debating just using the atmosphere catch can and putting one of those socks over it for that reason.

The PRV(Pancake valve) delete doesn't seem like a bad idea, since I don't think it's ever supposed to completely shut under normal operations. If you had a big turbo an rev'd the engine past 5k then it probably would shut and blow the seals.

[old guy]

Removing the PRV is a poor decision. The PRV is an integral component of the block breathing system. Clicky click®

[EuroxS4]

If the car is stock deleting all that stuff is not gonna give you any benefits. If Its highly modified. Its the best thing you can do

[B5carl]

Removing the PRV is a poor decision. The PRV is an integral component of the block breathing system. Clicky click

Even if the car is built? I've seen alot of guys delete for big turbo set ups which is what my plans are. I agree that it should be there but wanted someone who's tried to monitor crank case pressure with and without it

[B5carl]

If the car is stock deleting all that stuff is not gonna give you any benefits. If Its highly modified. Its the best thing you can do

Big turbo is exactly what my plans are. I just wanted more insite and feedback from people who have deleted both and how it runs. Alot I people keep saying it runs fine but that does not make sense as to why it was designed to be used on the motor only to be removed.

[B5carl]

I'm realizing now that the best purpose for the PCV is to introduce vaccum to the crank case and pull fumes directly into the intake manifold. This prevents greasy build up inside the intake, intercooler, and throttle body.

The PRV is to control the crankcase pressure going to the intake but I still think I could be deleted because if it closes at high RPM with boost, and no PCV, or even fails to reopen then that wouldn't be good. Also never heard of that happening before.

I just need someone to verify if what I think is correct or not.

[old guy]

When you are under a high boost condition the PCV closes to block boost pressure from entering the block. The PRV functions to prevent excessive vacuum from being pulled on the block from the turbo side. Excessive vacuum can cause an increase in oil consumption.

The PRV diaphragm will close if the vacuum is excessively high on the turbo side. A small amount of vacuum will still be allowed through the bleed hole in the PRV vacuum tube. The PRV will open when the block pressure/vacuum differential is higher on the block side, thus preventing the block from becoming pressurized by blow-by gasses.

[B5carl]

When you are under a high boost condition the PCV closes to block boost pressure from entering the block. The PRV functions to prevent excessive vacuum from being pulled on the block from the turbo side. Excessive vacuum can cause an increase in oil consumption.

The PRV diaphragm will close if the vacuum is excessively high on the turbo side. A small amount of vacuum will still be allowed through the bleed hole in the PRV vacuum tube. The PRV will open when the block pressure/vacuum differential is higher on the block side, thus preventing the block from becoming pressurized by blow-by gasses.

Alrighty I appreciate the clarification

[Turbavanttro]

I kept my PCV system in my BT build and have zero issues for the 8 years since finishing the build. I see no reason to delete it. It's not a complicated system.

[B5carl]

I kept my PCV system in my BT build and have zero issues for the 8 years since finishing the build. I see no reason to delete it. It's not a complicated system.

after owning this car for a couple of years and studying the AWM vaccum diagram from my Bentley manual I honestly think it's extremely simple and it all makes sense. I did look at your pics and you do not have the PRV(pancake valve) installed or at least in vision so you need to explain that. I see you have the 42DD catch can but I can't see what's after that.

[Turbavanttro]

after owning this car for a couple of years and studying the AWM vaccum diagram from my Bentley manual I honestly think it's extremely simple and it all makes sense. I did look at your pics and you do not have the PRV(pancake valve) installed or at least in vision so you need to explain that. I see you have the 42DD catch can but I can't see what's after that.

My pancake valve is installed between the catch can and the TIP.