What the hell is this... a "bolt-on"?

[striktlyaccord]

So I see these things on a lot of cars (yes, even Accords)... the mini-looking filter on the valve cover.  Here's an example of what I'm talking about:



My question is, what is the point of it??  It looks neat, but I never understood what they were for.  I've also seen that port on the valve cover be totally exposed with nothing on the end of it, or have a line attached to it that ran to an oil catch can or something.  However, in looking at my K24 engine, that port has a complex system of lines connected to it, as shown here:



The blue circle is where the filter would go.  The yellow arrows show hoses that seem to go to the aftermarket intake, the throttle body, and the area of the valve cover where the upper radiator hose attaches to.  The red arrow shows the big clunky looking piece that attaches to the intake of which I have no idea what it does, or if it's even needed since on other intakes I've just seen a straight hose there.  Again, I think the filter looks nice, but I'm not sure how it'd get installed without removing all of the other hoses, which must serve important purposes.    So, drop some knowledge on me homies.

[skizot]

It is an oil breather element. Some people prefer to have the breather element instead of having the oil circulate back through the intake.

[timot_one]

What Scott said.  Basically, this is for your valve cover to vent any oil/pressure back into your combustion chamber to be burned up and spit out your tail pipe via your intake.  Some people don't care and just have it vent out atmospherically.  The filter is there so nothing goes in.

[Mr Eazy]

What Scott said.  Basically, this is for your valve cover to vent any oil/pressure back into your combustion chamber to be burned up and spit out your tail pipe via your intake.  Some people don't care and just have it vent out atmospherically.  The filter is there so nothing goes in.

is this recommended or an oil catch can would be a better alternative?

[Mike]

A catch can keeps it out of your combustion chamber, and this doesn't in my understanding.

[NWINNIE34]

debating this whole issue with my friend who runs an oil catch can on his 99 big turbo passat
he seems to think if you vent this out into atmosphere he would fail emissions tests (new jersey)
i disagree but dont have any facts to back up my opinion.

i dont remember any type of emissions tests being done when i got my car inspected... and something like this would never show up or be recognized from a tailpipe test right?

someone would have to physically open your hood and stare down your engine looking for faults, which i would think 99% of the time they wouldn't even pick up on something like this
would this effect emissions ?

[Mike]

It has the ability to effect emissions because if you were burning enough oil your car would throw a CEL, and you would fail emissions. Chances are if your car was burning this much oil and inspection sticker would be the least of your worries.

[timot_one]

A catch can keeps it out of your combustion chamber, and this doesn't in my understanding.

Technically, both the catch can and the itty bitty filter keep the oil from re-circulating back into your combustion chamber.  The catch can just allows the other gasses to vent back into your combustion chamber, while the itty bitty filter just vents it out into the atmosphere.

[Jeff Likes Bagels]

So you could kind of say that the little filter is a poor-man's catch can?

[Knocturnal84]

well they pretty much said it all but wow that is some engine bay you found there..... i never saw those kinda individual coil(MSD)packs on our engines...looks sexy

[striktlyaccord]

So the little mini filter just vents gasses and oil right into the engine bay?  That can't be too good.

But still, I can see how the filter allows for the removal of the hose that connects to the intake (since the gasses no longer need to vent through the intake system), but what happens to the other lines I pointed out (the one that connects to the throttle body, and the other that seems to connect to where the radiator hose attaches to the lower part of the valve cover)?  Do they just get plugged up, or do you need to reroute them somehow??

[timot_one]

I think you're seeing things in that first picture you posted.  The valve cover vent goes to your intake before the throttle body.  There are no coolant lines involved in that.  Honestly, the best thing for you to do is get an oil catch can.  I have one that I will give you if you want it.

[striktlyaccord]

^ I don't think I'm seeing things.  I'm gonna have to take a better pic or snap a quick video to point out what I'm talking about.  There's def. more lines in that general viscinity that must do something... maybe part of the throttle body coolant system (that bypass mod which I never did).  It's frustrating that I can't explain this.  And the free catch can is tempting.

[striktlyaccord]

Here's a better pic, courtesy of Alex over at V6P:



So there are two other hoses/lines (blue circles) that are connected to the main metal line (red arrow) that the filter goes on (Rolo put his filter on the end of the line as opposed to right on the valve cover itself).  I'm confused as to what those other two lines do, and if you decide to put the filter right on the side of the valve cover as opposed to how Rolo did it, than what do you do with those two other lines??

[timot_one]

Those two other lines are probably the coolant lines that are not connected to the line that goes to your valve cover.  Don't over think this one, it's literally a vacuum line that goes from your valve cover to your intake.  Some of them have that weird plastic valve thingy, but others don't.  Those other lines are just next to that vacuum line and don't have anything to do with this mod.  IMHO, it's a waste of money and I would just leave it alone.  It's basically just one of those "look at this" mods that does nothing for performance.