Importance of an oil catch can?

[nissanrcer240]

Im just trying to find out exactly what the oil catch can does. Because in the new turbo magazine, theres a yellow 240sx on the front cover and inside the mag if you look at the engine bay shot it looks like he eliminated his oil catch can and ran a line strait through it, from the T on the valve cover, strait to the line that come from the back of the engine. Then he put a little breather filter on the other side of the T. On the stock setup theres a hose that runs off that T into the intake piping before the turbo. Is replacing that line with a breather safe to do?

I have a little breather filter on the other side of the T coming off the valve cover too, because I put an aluminum intake pipe in replace of the stock rubber pipe and it didnt have a place for the line to run into it. I know thats not the way it came stock but is that hurting my motor in any way by having that breather filter coming off the T instead of the line running into the intake pipe?

[rudee023]

Alot of people replace the stock baffle with a hose running from the "T" to the back of the engine. For the other side, you have a couple of options.

1. Run a filter. (If you have large amounts of blowby, it will eventually get saturated with oil)

2. Run a line to the inlet of a catch can and a filter on the outlet of the catch can.

3. Run a line to the inlet of a catch can and a line to the stock location on the intake.

Either setup is fine. The only damage that would happen to your engine might be if you plug everything off with no release.

[nissanrcer240]

So the way I have mine setup is good. My friend has been telling me its not right and that its 'susposed' to be recirculated back into the intake pipe for a reason but couldnt tell me the reason why exactly. So the oil catch can is just like a filter in a way? Or is it just to hold oil that over flows out of the valve cover?

[ride4lame]

it would be best to have it plumbed back into the intake like it was stock.i wish i could remember the exact reason, but there is a preasure in the valve cover that would become different if air was being pulled into the turbo...so i would think you might have to much pressure in your head....i have a breather filter though and don't see any ill effects...

[f150intally]

i think the reason it is plumbed into the intake is because the air has already been metered by the mass airflow sensor. I could be wrong. I run mine like option 2 and it runs great.

it would be best to have it plumbed back into the intake like it was stock.i wish i could remember the exact reason, but there is a preasure in the valve cover that would become different if air was being pulled into the turbo...so i would think you might have to much pressure in your head....i have a breather filter though and don't see any ill effects...

[Rosco]

I think I have the same question but I'll ask anyway. I installed an OBX header on my redtop so there is no way to keep the black box(dunno the name) that connected to the "T" on the valve cover, so all I did was put a breather on the one side and ran a hose to where the black box was connected. WHat are the problems in doing this? Other solutions? I have yet to install my SR so I still have time to do anything to it before I start my swap.

[9095240SXDUCK]

I just Run my From the T to the top of the Air Box! And it been running fine!

[Def]

Oil vapor being openly released into the atmosphere would not allow the car to pass any kind of emissions regulations when originally sold. So they plumb it back into the intake tract so the oil vapor gets burned during combustion.

I plan on just running a catch can where the stock baffled box is and venting it to the atmosphere. Plug the "intake" side of the T on the valve cover and then you're good to go.

[USsil80]

the best thing about a catch can is you can see if you are getting a lot of blow buy... god way to see if the rings are starting to let go.. or other problems starting

[240SXer]

I don't run a catch can and i'm fine. I don't have any large amount of oil in my pipes or anything. All the ones I find look to bling for my sleeper look....

[USsil80]

greddy has a good looking peice that is pretty cheap and you can place it somewhere that you can't see it

[cheez80]

i'm thinking of plumbing that line to an oh-so-jdM pocari sweat bottle. =D

i think some guy on freshalloy or somewhere is running a gatorade bottle =P

[rudee023]

You cheap bastard, who

i'm thinking of plumbing that line to an oh-so-jdM pocari sweat bottle. =D

You cheap bastard, whoever helps you with that should be drug out into the street and shot. Oh, wait!

[mynameisjonas]

what could be the problems if there is alot of blowby oil?

[mynameisjonas]

i'm wondering because i'm trying to get my car running right. there is ALOT of oil coming thru. i don't have my catchcan hooked up yet. (it's hooked up but not right). i'm really nervous about what is the cause of it. can someone please help me out with this?!

[DanielIser]

The only problem with aftermartket manifolds and running a straight hose from the t to the back of the motor is if the hose or the manifold is not heat wrapped some how the hose manages to catch fire somehow from the heat and cause problems like that. I should know happened to me a couple of weeks back, really sucked, but i got it out before to much real damage, other than the hood insulation being removed and my brake fluid lid being warped from heat.

[Bluefire]

Ok on the valve cover there are two vents. One is the PCV(Positive Crankcase Ventilation) valve that opens only under vacuum. This basically sucks out the pressure in the head, along with oil vapors during vacuum and burns it in combustion. The other "T" vent is for when your on boost. The PCV valve will close and the crankcase will need to release the pressure from blow by. Thats what the "T" on the valve cover is for. Now there is another vent on the back of the block to release pressure also. THIS IS NOT A DRAIN FOR THE VALVE COVER. This means you have pressure coming into the back of the T as well as from the side. All this pressure is then released out the front of the T into the intake tract. Now in all the pressure being released there is oil vapor from the motor. This oil vapor is normally recirculated back into the combustion for environmental reasons. But as we all know this robs us power!!

Here is where the catch can comes in. The hose from the front of the T goes to catch can inlet. The outlet can either go back to intake tract or to a breather. But the problem with most catch cans is that they are usually not baffled. Ideally, you want something in the can to filter out the oil vapers, rather than using just the walls of the can to trap oil. This way, air coming out of the can will be relatively clean. Also depending on how much boost your running you will need to get the right size can accordingly. I hope you guys learned something

-Bluefire

[mynameisjonas]

thanks, that was a good explanation of it all.

[Sellek83]

Having your breather pipe connected to your inlet tract provides a vacuum, this vacuum draws the gases from the crank case making it the most efficient setup to reduce crank case pressure. A decent baffled catch can should be CATCHING the oil vapour as it passes through the can whilst the air continues to the inlet. These gases may not be fresh clean air but if your running a cold air intake this will completely overwhelm the amount of air coming from the can, and dilute it so much with clean air it will not make a difference.

The vacuum is the reason why ALL engines are plumbed this way from the factory, it's simply the most effective way to reduce crank case pressure.

As soon as you add a filter(a way for air to enter or exit) the vacuum is lost.