bbyevo8u

iTrader: (14)

i having some crankcase pressure issues and i was going to install a saikou michi duel stage catch can, but i dont know if i should take the pcv valve out or not?

whats the pro & cons on taking the pcv valve out on a modded evo?


John

Kracka

iTrader: (49)

Leave it, you don't want positive pressure getting into the crankcase.

BluEVOIX

iTrader: (69)

Are you referring to the Check valve part of the pcv valve?

If you look the pcv behind the valve cover connects to the intake manifold. When you drive around staying off boost, the manifold is sucking in air/blowby gasses from the valve cover. The check valve works by staying open during normal driving and closing when you boost. Its very important that it closes during boost so that pressure does not travel from the intake manifold into the valve cover. If the check valve malfunctions or you remove it, next time you boost a number of things will happen.

-you will blow off the dip stick and squart oil all over the engine bay
-lose power because the positive pressure you'll create in the crank case will work against the motor.
etc...

If your having crank pressure issues a catch can will not solve that. A catch can is just to separate oil that sometimes travel out the pcv with the blowby gasses and to prevent the oil from creating a oil resedue accumilation in the intake system.

Your issue is more like caused by a faulty check valve. Try replacing the check valve and also make sure your pcv's arent clogged etc.... Also if your on a built motor with loose piston to wall clearance, this would further increase blow by gasses and you would benefit with larger or more pcv's.

Hope this helps,

06MREvo

iTrader: (90)

OP, check this thread out...some good info in it...

https://www.evolutionm.net/forums/ev...re-issues.html

I deleted my PCV valve and now just run 2 check valves, 1 going into the catch can and 1 coming out to the intake manifold...

Srr

iTrader: (7)

good info

Houstonsc300

iTrader: (1)

Couldn't you just T both of the hoses from the valve cover, cap the nipple at the manifold and run that hose into one port of a catch can. The other hose would go from the intake pipe to the other port on the catch can to pull crank case pressure. That way you can remove the check valve, but still pull crank case pressure at idle and at boost. might not pull much though at idle though as compared to the stock pcv hose connected to the manifold, but pretty common setup on a lot of evo's.

bbyevo8u

iTrader: (14)

where is the check valve located?

BluEVOIX

iTrader: (69)

Popping the hood and looking straight at the valve cover. Right behind it on the passenger side.

During closed loop operation (non boosting), the intake manifold vacuum draws gases from the valve cover area and also crank case area. When you start to boost the intake manifold is no longer pulling air, but pushing. This turn in direction of air flow pushes the valve inside the check valve to close and not allow air to be pushed into the valve cover and crank case. The rest of the blow by pressures are relieved only through the driver side port of the valve cover.

Blow by gas comes mostly but not only from the crank case area where gases escape passed the piston rings. There are ports in the block and head that the gasses follow through to under the valve cover where they escape through the pcv/ports so that it does not pressurize the crankcase. If it does fail and the crank case pressurizes the usual first signs would be dip sticks blowing out.

Basically fill your mouth with air and try to quickly bite up and down. Notice how through each bite the air in your mouth pushes your cheeks and the resistance you feel. Eventually your lips want to leak out the air. Same with the motor and hence the PCV system was created.

Not my photo. Borrowed it from another thread.

joyce1bro

This is good info.. may have been my issue for the dipstick popping out.. but then again I didnt have any lines connected to the intake mani?? so there wouldnt be any positive pressure under load right? any reason why Buschur and other companies dont use them?

bbyevo8u

iTrader: (14)

thanks BLUEVOIX, i know the picture shows the pcv valve but where is the check valve, inside the pcv valve?

also what would you suggest i do to help fix mypressure problem? you said that catch cans wont help, how about breather filter/ catch can?

John

BluEVOIX

iTrader: (69)

I think its because they vent to atmosphere like I do. If you vent out without recirculating, a check valve is not needed.

The check valve is that little section connected to the L part sticking out of the valve cover. If you look on the floor is another check valve. It just screws on to the L section. If you think about it, the check valve in this case is part of the PCV. PCV is positive crankcase ventilation. Its basically the ventilation of positive pressure from the crank case area.

Some engine setups have a crank pressure ventilation system setup straight off the lower block with a factory recirculating catch can! I think I saw it on my friends honda if i remember right.

The catch can just separates oil from the blow by gases are relieved through the PCV system. It's design and function does absolutely no benefit to relieving crank pressure. Well actually I only saw one that does and that was buschurs recirculating catch can because the design allows pressure to be relived from the crank case through the dipstick tube. Basically like adding another pressure relief port.

If your having crank pressure build up issues and you replaced or verified the check valve is function correctly then you have other issues that are causing. Its a little more complicated now. But you would probably need to add more pressure relief holes on the valve cover or enlarge the current.

Some causes could possibly be from piston rings starting to leak more or valves leaking etc.. A built motor that is setup with loose piston to wall clearance may leak more blowby than a tighter clearance and will require more ventilation. Also maybe the looser built motor might benefit from a thicker viscuosity oil, but I'm assuming that it might help seal it. But I think mostly the thicker oil on a looser motor will help properly keep the areas lubricated to spec and burn less oil.

Hope this helps and please feel free to correct me if I'm wrong.

ChadS

iTrader: (5)

This is how I just set mine up, previous owner had a blow through fitting where the pcv valve was that went to a catch can and right back to the intake manifold. As far as I know this is exactly what you do not want, manifold pressure would be able to go into the valve cover.

Stradag

iTrader: (17)

I would also like to know if this will work. It seems that the suction of the intake will still suck vapors out at idle and it would actually vent more during wot seeing that the old pcv valve port is now open under wot having the intake tube sucking vapors out through both ports.
Input would be appricaited.

boostedwrx

iTrader: (27)

Took mine out long time ago. The inside of my Magnus is just as pretty as the day I put it on.

My03evo

iTrader: (1)

I think I know what you mean but I wouldn't run like that in a picture unless you have a check valve between the catch can and engine, or else when there is crank pressure it will blow any oil from inside the catch can and out into the intake and into the turbo. If theres a check valve the crank pressure wont make it to the catch can. and I would run it to the intake mani instead wheres theres VACUUM, by tapping into the turbo inlet there's no actual vacuum because there's not much restriction (unless u have a 100% restricted air filter), but the intake mani has vacuum because of the throttle body plate being close or partially closed anyway...if that makes sense to you.

Read the thread posted above and search for others on here and you will understand everything.

There's a diagram of how mine is setup on one of those threads and it's still using pcv on the intake mani port with a catch can and Krank vent (just an expensive check valve) and I no longer get any oil inside my intake or on top of my pistons when I took my plugs out and looked. There's also a link in one of the links where to get the in-line check valves cheap too. Deff use one so you're not pressurizing the catch can and blowing the oil back into the intake and soaking your turbo/intercooler and engine. Me and many others would only use a Saikou catch can also because of the baffling he puts inside to catch all the junk and oil vapors going through it.