Crankcase pressure help

[spadepro22]

I have a oil catch can, one line from valve cover to can and other line from can to atmosphere. I have the problem with dipstick blowing out under boost and Im going to try to get a compression test done tomorrow. In the meantime I was wondering if Im venting enouf with the way my catch can is set up. Is there a better way without buying another oil catch can and Im I suppose to clean the catch can.(new pcv install already) Thanks

 

[Calan]

http://www.dsmtuners.com/forums/articles-engine-fuel/366890-4g63t-pcv-system.html

 

[CrawlinZX14]

Umm for that catch can to work, you need to have a vac draw on it in order to pull the crap from your crank case into the can and catch everything. I suggest hooking up a line from the can to the tube between the MAF and the turbo. It will keep a constant draw of vac, and will also catch all the crap into the can. And I suggest stuffing a few green scotch bright scrubbies into the can unless its baffled to catch/filter all the particles out of the air as it passes thru.

 

[MathixPerforman]

I agree, when you are under boost you create crank case pressure and when the turbo spools it will pull vacuum and relieve pressure from the engine. There is also a spring mod you can do on your dip stick but it would be better to relieve pressure instead of forcing it to stay in the motor. Sorry if I am just repeating what somebody else said but this is the newbie forum and I haven't hit 30 posts yet.

 

[DSM1G90]

...why worry about a compression test? Sounds like you got plenty - including a lot of blowby to push that dipstick out.

Under boost, the PCV valve closes completely, making the blowby pressure under the rocker cover to head back into the intake via the port on the end of the cover. Some put a catch can on that line as well.

 

[Calan]

...why worry about a compression test? Sounds like you got plenty - including a lot of blowby to push that dipstick out.

If his crankcase pressure problem is caused by excessive blowby making it past worn rings, compression will be low.

 

[2slow4now]

Under boost, the PCV valve closes completely, making the blowby pressure under the rocker cover to head back into the intake via the port on the end of the cover. Some put a catch can on that line as well.

Yeah you don't want all the oil and crank case yuckies coating all your IC lines.

I had an idea of running it back to the intake but before the air filter so the air filter will filter out some of the oil too. What do you think Calan?

 

[miguelmcv]

I have running my catch can with the lines to the vc and to the Intake...,,,,, The catch can has a filter on top which release the crank pressure under boost.

The Catch can has a valve that release the pressure Out, and will shot on idle, so it works like factory when idle (No idle surge).

 

[dsmcurse]

my valve cover has two 5/8'' hose barbs welded to it, two very big 5/8 hoses vent into a catch can and top of catch can is open vent. i too have a problem with my dipstick blowing out. i thought about putting a spring from dipstick to powersteering pump bolt to keep the thing from blowing out.

heres a better idea, its obvious the block builds pressure under boost. the pressure is slow to vent from block to head to valve cover to catch can. so im gonna take my dipstick tube, and a second donor dipstick tube. cut them in such a way that they can be Y'd together and welded. the one hole will be normal dipstick operation. the other hole will get a 3/8 hose clamped onto it and then run that hose to catch can.

this is my homemade block breather situation. stupid honduh come stock with block breather on back of engine. whats up with that?

 

[2slow4now]

^^ Thats not a bad idea. Maybe just find a steel nipple that could be notched and welded to the tube and drill a hole into the dipstick tube and like you said run that to a can. The open vent catch can isn't the best way to try to vent but alot of people do use them. If your going to do the spring deal you could just weld a tab with a hole in it on the side of the tube and hook the spring to that. I've seen those for sale before but don't remember what site.

 

[JuGs]

Did you replace the pcv valve with a OEM one? Not one from your local parts store? The local parts store ones are jsut out the package. I got one and had same issue so I ordered a OEM one and it helped greatly

 

[Calan]

I had an idea of running it back to the intake but before the air filter so the air filter will filter out some of the oil too. What do you think Calan?

It would be the same thing as running the can open to atmosphere, except with the added chance that you could soak you air filter with a nasty oily mist... depending on the type of can and where/how it's hooked up.

I have running my catch can with the lines to the vc and to the Intake...,,,,, The catch can has a filter on top which release the crank pressure under boost.

The Catch can has a valve that releases the pressure out, and will shut on idle, so it works like factory when idle (No idle surge).

That is nothing how the factory setup works, and is not recommended.

so im gonna take my dipstick tube, and a second donor dipstick tube. cut them in such a way that they can be Y'd together and welded.

Why not just run a proper catch can setup?

 

[dsmcurse]

do have proper catch can set up, block still has NO breather tho. trust me, the dipstick tube breather setup is a good way to go. lots of boost makes lots of crankcase pressure.

 

[Calan]

my valve cover has two 5/8'' hose barbs welded to it, two very big 5/8 hoses vent into a catch can and top of catch can is open vent. i too have a problem with my dipstick blowing out ...

...its obvious the block builds pressure under boost. the pressure is slow to vent from block to head to valve cover to catch can.

The excessive pressure is due to your lines and open filter having too large of a pressure drop compared to the amount of crankcase pressure you are building. It has nothing to do with how far the gases have to travel before they exit the can.

The only way to properly relieve that pressure is by:

a). lowering it at the source, or
b). using a lower pressure on the can outlet to help overcome the pressure drop, or
c). increasing the cross-sectional area of the path it takes out of your engine.

do have proper catch can set up, block still has NO breather tho. trust me, the dipstick tube breather setup is a good way to go. lots of boost makes lots of crankcase pressure.

Just out of curiosity, did you read the article I linked to in the second post?

 

[dsmcurse]

i still think the block see's alot of pressure. and if the the only source of ventalation is from the top of the valve cover than yeah, its possible to keep blowing out the dipstick. catch can aside. forget about what kind of can it is or where its mounted. i just keep thinkin the valve cover vents arent quite enough. as we all know there is NO block breather. honda engines have block breather, nissan and most mazda engines too. mitsu has NO block pressure vent. so like i was saying, i think a custom dipstick tube would work good. you could still have normal dipstick operation, but if it was Y'd at the top and had another hole that could be hosed back into the oil catch can i think it would work wonders on releving crank case pressure.

no matter how good of shape the engine is in, no matter how good and new all your gaskets and seals are, under lots of boost there is crankcase pressure. extra strain and work is put on these gaskets and seals under crankcase pressure. it is possible to take alot of work load off of the gaskets and seals with a good ventalation system.

in my opinion, the factory 3/8 hose barb they give you next to the cam sensor isnt even close to being enough ventalation. the factory vent they give you plus the pcv valve are blocked off on mine. then on top of valve cover there is two 5/8 hose barbs that are hosed into catch can. dipstick will still pop out some on 30psi power pulls. so it makes sense to me to make the dipstick tube into a block breather

 

[Calan]

I've designed, built, and sold over 100 custom catch cans and PCV systems for these cars (including Shep's Talon as a point of reference)...and to my knowledge, all of them work without a "block breather" or dip stick that has been modified for ventilation.

It's your car; do what you want. But please do not imply that what you are proposing is necessary, because it isn't.

 

[dsmcurse]

no its not necassary but i dont see how it could hurt. i think i would do more good than bad thats all

 

[spadepro22]

Didnt get a comression test done because of rain, but still is one catch can good enouf. From what I read, I just need to put the line that is venting into the atmoshpere into the intake?(and I want to keep it simple)

 

[redpit]

i will agree with calan. and the pcv is very over looked issuse on all turbo cars and none turbo car alike. and excess crank pressure can contribute to seal leaks found on almost most every car import and domestic alike. i am just speaking as a tech . i'am paying close attention to this post because i want to mod. pcv the best way possible.