oil catch can install

[3p141592654]

That may be true for a track car, but it doesn't hold for a street car that sees considerable time at idle and low rpm and low load. Under those conditions the amount of pressure in the crankcase is low, and ventilation will be inadequate. This will results in a lot of condensate remaining in the engine, especially water in the winter.

 

[Grimsta]

Even at low RPM there is enough pressure for the vapors to evacuate into a vented can, or idle. Ever take your oil filler cap off and let the car idle for 30 min? You'd have oil all over your engine bay thus indicating that oil and vapor doesnt just stay trapped in an engine if it doesnt have vacuum, it has the freedom to evacuate.

But talking about condensates, a catch can is supposed to remove the water from the oil? If you have water in the oil they're both goin into the can in vapor form. A can that used to catch vapor is going to only pull contaminates out of the oil, if its in the oil its in the oil and a catch can cant separate that, unless its like a filtered, recirculated catch can or some craziness like that

 

[IJ.]

Where you'll run into issues is when you give it a squirt and back off you end up with 0 flow out of the engine due to the turbo compressor backing up if the BoV hasn't opened and this WILL build crankcase pressure.

I just added a real PCV valve to my system and it's made a huge difference as my motor was exhibiting signs of blowby/failing engine even though it Comp and Leakdown tested 100% fine.

ALL symptoms are now gone.
(I had mine plumbed with -10 from the cam covers to between the air cleaner and turbo)

 

[3p141592654]

Grimsta, the ability to evacuate water is massively increased under vacuum due to the lowering of its boiling point. You want the crankcase under vacuum, especially under winter street conditions where water accumulation is an issue.

I never said there was no pressure at idle, I said inadequate. Given the cam lobe under the oil cap is flinging oil everywhere, I would expect a mess no matter what the pressure is.

 

[tekdeus]

Where you'll run into issues is when you give it a squirt and back off you end up with 0 flow out of the engine due to the turbo compressor backing up if the BoV hasn't opened and this WILL build crankcase pressure.

I just added a real PCV valve to my system and it's made a huge difference as my motor was exhibiting signs of blowby/failing engine even though it Comp and Leakdown tested 100% fine.

ALL symptoms are now gone.
(I had mine plumbed with -10 from the cam covers to between the air cleaner and turbo)

Interesting. Did you add a PCV one-way check valve to the intake manifold? Where does it connect to the can, or other line that is also pulling from the turbo inlet?

Any tips on cleaning the TB port? I can't seem to unclog mine.

 

[IJ.]

The stock system IS done this way.

One line goes to the accordian hose the other to the TB, on early cars they had an actual valve but on late cars they just have a small orifice.

My system replicates it adding in a catch can and a valve.

I have a large -10 line from the CC to between the Filter and Turbo then a small -6 line from the CC to the FFIM just behind the TB.

 

[grimreaper]

perhaps ditch the stock tb orifice and plumb in a bit larger line with a check valve for more vac on the crank? Would this be of any benefit?

 

[tekdeus]

perhaps ditch the stock tb orifice and plumb in a bit larger line with a check valve for more vac on the crank? Would this be of any benefit?

Good point. I was thinking of doing the same by tapping and drilling a fitting into my EGR block off plate. But I also wanted to have a dedicated vac line there for my AFPR. I'm concerned about the PCV being so close to a vac line. Opinions? My TB port is super clogged so I may have to do this anyways.

I was also contemplating the benefits of having a vacuum operated valve, installed between the turbo pipe inlet and the catch can. It would be setup to open only under boost, so that when under vaccum, the PCV vac line would pull directly on the catch can and crankcase, and not pull a bunch of air from the turbo pipe, assuming that both lines are pulling vapors through the one port on the catch can. Is there an OEM or universal VSV I could use for this application?

I'd like to hear some opinions on if it is OK to be pulling that much extra vacuum/flow in both of the scenarios I just described (with and without the added VSV idea)

With the VSV installed, and using my 3/8" check valve, it would pull full manifold vacuum on the crankcase. Are the 2 valve cover breathers the ONLY crankcase breathers on the 7M? No other inlets?

 

[grimreaper]

only ones, i opened them up to 3/8 npt fittings.
never thought of making it so the tb port can ONLY pull from the crank case, in theory that would be very effective. Any down sides?

 

[C.44]

I was just thinking, over here they test exhaust gasses at 3k rpm for about 30 seconds. Now i will just say that i know a catchcan isn't a wonderproduct, i know it works to some extend but it isn't a airpurifier.

If you rev the engine up to 3k rpm, WITHOUT LOAD on the engine, you'd say that there is some vacuum on the TB PCV port right ? So if i'd have a similar pcv setup as Adjuster on the previous page, you think that the air it pulls in is actually not "cleaned" by the catchcan. Thus pulling in filthy vapours which will fuck me on my smogtest.

Wouldn't it be a good idea to put a T on the TB PCV port with on each end a checkvalve in different directions so that under vacuum it could pull fumes through the catchcan and under boost it could push air over the camcovers ? Does that make sense ? Ofcourse you'd have to T the exit side on the catchcan so that one end goes to the pipe between the airfilter and the turbo and the other end goes to one of the checkvalves on the TB PCV. Still make sense ?

In that case, vapours would always have to travel past the catchcan first.

i'd thought i'd illustrate it too to take away a bit of the confusion i cause a second ago

The valves are one-way valves ofcourse.

Now i know that the effects might be minimal but what i'm really getting at is, if i rev the engine to 3krpm will it draw in enough vapours to screw me over on a smogtest because it pulls in "uncleaned" air through the TB PCV from the camcovers ?

*puts on flamesuit...

 

[Grimsta]

Where you'll run into issues is when you give it a squirt and back off you end up with 0 flow out of the engine due to the turbo compressor backing up if the BoV hasn't opened and this WILL build crankcase pressure.

But see IJ, if it WILL build crankcase pressure that pressure is free to escape into the catch can. Pressure doesnt stay contained, it flows through the path of least resistance, and with the can vented it has free travel to the atmosphere.
I'm thinkin of this like a soda can. If you shake it up and open it it fizzes out. The can doesnt blow its seals. When the engine is "shaken up" the pressure will "fizz" out the top (cam cover vents) and into the catch can instead of bubbling over and getting on your hand.

 

[grimreaper]

not to nit pick but if pressure is resistance to flow wouldnt that mean there is no free flowing path? I know i had four front seals that spread oil all over the motor and a dipstick that loved to let oil out an all over the hotside until i routed larger pcv lines...

 

[Grimsta]

I see what you're saying, and it is right but instead of using generics for terms think of where that pressure actually is. There isnt pressure against the crankcase the pressure is IN the crankcase & it will flow to the area of least pressure which means it would essentially "evacuate itself" into the catch can since there is no pressure in the catch can

 

[NashMan]

my an fitting pvc system is just about done

have to plum my cheack vavle in then i am done can't weight cause that will be one thing off my list

 

[Davismj711]

Forgive me for resurecting this gem of a thread.

I have my CC plumbed as per JJ and Jdubs recomendation. Due to some untimely oil leaks ( location yet to be determined ) but it is looking like Cam seals or having to redo the cps o-ring again. CPS not leaking internaly.

With this discussion talking about leaks my plumbing has me a bit concerned. I am only on the 2500 mile mark of a total rebuild.

I would like to install the PCV valve as desribed by jdub. My stupid question is.....are PCV valves marked as per air flow ? If so how do we position it in the line above accordian hose that goes to TB ?

Thanks
Mark D

 

[jdub]

A PCV valve is a check valve...just blow through it to determine flow direction.

On the accordion hose side, you want flow toward the accordion hose.

 

[IJ.]

But see IJ, if it WILL build crankcase pressure that pressure is free to escape into the catch can. Pressure doesnt stay contained, it flows through the path of least resistance, and with the can vented it has free travel to the atmosphere.
I'm thinkin of this like a soda can. If you shake it up and open it it fizzes out. The can doesnt blow its seals. When the engine is "shaken up" the pressure will "fizz" out the top (cam cover vents) and into the catch can instead of bubbling over and getting on your hand.

OK plumb it your way and let us know how it goes..... :nono:

I don't pull this out of my ass it's based on practical experience.

 

[Davismj711]

Thanks Jdub

I believe I can find a PCV valve to fit directly into the accordian hose and then into my T going from catch can to TB.

With it plumbed as you have said, but w/o this check vavle could it be a possible factor with my current oil leak dilema ?

 

[jdub]

The system will work without the PCV valve if it's plumbed correctly...the valve simply helps put full vac on the cam cover ports by preventing flow from the accordion hose.

You need to figure out where it's leaking 1st...if it's from the head seals, no too likely the PCV is the cause.

 

[starscream5000]

OK plumb it your way and let us know how it goes..... :nono:

I don't pull this out of my ass it's based on practical experience.

You do realize that you're replying to an almost 8 month old post, right Ian?