PCV Delete Question

[blingsta]

Hi all

is it true that if the car has pcv delete, it is perfectly normal that they can throw out some smoke when you boot it on occasions?

[GVK]

Depends if it vents to atmosphere. Mine has a BSH delete from the USA and its sealed and never smokes.

[pudding]

Depends on the level of delete.

I think it's the full delete that can cause smoking.  A full delete is blocking everything off and just dumping the rear cam cover outlet to atmosphere.

This is bad on so many levels, but 2 reasons not to do that are 1) it's a flat-out instant MOT fail and 2) it f'ckin stinks.  The HVAC draws in those fumes.  Yuk.

I don't think a lot of folk understand the complexity of the OEM PCV system.  My advice is to just leave it as it is.  There is no gain what so ever in blocking off any part of it.  The intake valves are going to carbon up no matter what you do.  PCV deletes do not stop that.

[GVK]

Mine was on the car when I bought it, zero issues with anything PCV related...

[pudding]

Zero issues with the factory setup on mine either    Don't fix what ain't broke 

[GVK]

Indeed!! 

[blingsta]

i didnt mean to open a can of worms 

mine seems to have been done by RTech by previous owner...     i just wanted to know why i noticed a puff of smoke behind me when floored it (only done once in a while) 
and it was a mate who told me that it sometimes blows a puff due to the PCV delete

[ROH ECHT]

The main factor, or change, by deleting the PCV is that a PCV delete or catch-can eliminates vacuum applied to the crankcase. Unless you run a tube from the rear PCV outlet of the rocker cover to a catch-can...then from the catch-can to the turbo inlet and retain the PCV (would need to be a Rev.-R PCV so the rear vent isn't required to be valved). Removing the tube between the intake manifold to PCV eliminates crankcase vacuum. Applying vacuum to the crankcase improves ring (and valve guide) seal to reduce blow-by. So sure....some have no troubles and others do. It is dependent upon the condition of each engine. Some people, thinking they know stuff, have even deleted the PCV and plugged off the rear vent tube. And in doing so they closed off all crankcase venting altogether. And then seals leak and worse. Without the PCV and application of vacuum, the crankcase requires venting to at least be allowed to maintain one atmosphere of pressure.

So, it is up to you. The choice is; do I want to delete the PCV just so you never have to replace a PCV again? Or, do I want to ensure it has the best chance of operating as good as it can for as long as it can.

I ran a BSH delete for some years (4 to 6). It eventually smoked out the exhaust and I then rebuilt the head and gave it new rings in 2016. I went back to the OE PCV at that time because I wanted the vacuum application again. Never had a PCV fail before or since those years of running a PCV delete.

[blingsta]

 
so if there are no gains to be had by deleting the pcv, why do RTech do it?  especially if you guys say that it could be damaging to the seals etc?

[GVK]

Interesting stuff. Hey is your name Brad? You answered my question about P0299 on TFSI tuning? Gary.

[blingsta]

No mate..  im not him

[GVK]

Question was to Roh Echt lol

[ROH ECHT]

Yes...LOL...I'm Brad. Hello Gary.

[ROH ECHT]

so if there are no gains to be had by deleting the pcv, why do RTech do it?  especially if you guys say that it could be damaging to the seals etc?

Perhaps I wasn't very clear....the PCV delete alone, done correctly, is not damaging. With that said...with a PCV delete; some with worn bits (valve seals and guides or rings) may instantly, or will soon have smoke from the exhaust if their bits are worn more than others. So it isn't damaging...it just changes the condition within the engine for the loss of vacuum.

Once in boost, with a PCV mounted, the vacuum to the crankcase is cut off. Regardless the set-up (Stock PCV, PCV delete, or Catch-can) it's all the same at that point, because then is when the crankcase releases blow-by pressure to the turbo inlet or atmosphere. Vacuum just provides better sealing at the rings and valve guides when in vacuum.

So, the PCV delete only; 1) eliminates the PCV and 2) loses its benefits of vacuum when not in boost.
The only gain is; 1) you never have a PCV failure.

As for why R-Tech does them is probably because they are asked, and paid to. But I think Niki will say, or says the PCV has benefits.

My advice has always been if you are blowing through quality PCVs often due to your extreme build...then yes, get rid of the OE PCV and allow the crankcase to breath more. But if the PCV with xxxk miles on it has finally failed, then replace it with a quality replacement. The PCV delete isn't necessary just because it is made available. I kept mine just to use if I ever need a PCV and my local small dealership has to order one for me...making me wait a couple of days.

[pudding]

Interesting debate 

First of all, all car manufacturers are mandated by law to make their engines ingest their post combustion gases, both by EGR and PCV.  Consumers and tuners alike messing with said emissions controls are actually breaking the law, but in the UK at least, it's very loosely regulated.

Secondly, you might think, ah well, if it's just an emissions thing, I can just delete it then. Winner winner chicken dinner, no more bunged up intake valves and more power, hurrah!

Well, not really.....

Even on a healthy turbo engine, blow-by pressure can be as much as 20-30psi, maybe more on a remapped engine. If that pressure is not evacuated by a PCV system, that's 2 bar+ of pressure that can force it's way back up the turbo oil drain hose and over whelm the bearings/seals.....hence the blue smoke.

How do you stop that from happening?  Funny you should ask, a PCV system! By feeding the rear PCV into the turbo, it forcibly evacuates this pressure thereby allowing the turbo to dump it's oil back into the sump unrestricted, and also create a negative pressure behind the piston rings for better compression.  And that's just the boost side of things.  There's another side to the PCV that deals with the vacuum side of things, again, to help with cylinder sealing.  Not to mention an oil separator attached to the oil filter housing, which is a 'catch can' of sorts.

So there you go, that's why the OEM PCV system is so complicated, and it's not just for emissions reasons.  It's basic physics.

As for carbon fouling, you will never get rid of it on a DI engine, even with a full delete.....because exhaust reversion. It's a natural phenomenon all engines suffer from.  Cam overlap allows a certain amount of exhaust carbon back through the intake that bakes onto the valves, plus oil dripping down from the valve stems is also baked on in the big chunks we've all seen in pictures.  Carbon fouling is more to do with that than the PCV system.