Oil Catch Can

[RtN]

Hey do NAs need these Oil Catch Cans? and where do they connect?

[dsp26]

http://www.ozhonda.com/forum/showthread.php?t=16874&highlight=catch

[TheSaint]

but do NA need them?

[dsp26]

but do NA need them?

only if your getting blow-by already at which point you should be getting new piston rings...

- when your piston rings are fried, combustion pressure breaches past them into the crankcase/block
- pressure build up vaporizes oil and pushes them out the pcv valve back into the intake system.
- this is noticable when you take off your TB and realise how much oil you have on the surface

This is the factory method of making this issue maintenance free by burning off the 'leak' as the average enthusiast/motorist wouldn't even bother emptying a catch can let alone do a proper 5000-10000Km service.

This is also why a catch can has to be on the PCV->Plenum line and not where all the ricers put it on the rocker breather->intake hose. I hate seeing this coz what these fools don't understand is that the air is going towards the engine... why would you need a catch can to filter the air from the intake already filtered by your pod/airbox? heck this is why people stick those breather filters on there... and even that ricer mod is only required if your intake hose doesn't have the nipple to allow you to connect a hose to the breather.

To get the most out of installing a catch can:
- do TB clean with TB/Carby cleaner
- change oil as any TB cleaner that also leaks past your rings will deteriorate the viscosity of whatever oil you have in your block
- install catch can


***EDIT***
look at the pics i posted in that install thread and see how much oil i caught in a week with my mini catch... but this is cause i vtec my car alot = higher combustion pressures. the new proper catch i installed as oil all over the clear indicator hose.. wether its staying in there or not is another story.

[dsp26]

this thread also linked from my last post in the install thread explains where its supposed to connect:
http://www.ozhonda.com/forum/showthread.php?t=70302

[Limbo]

for NA cars, ones that keep redlining or revving hard should get them. Its more of a precaution than anything else. Just stops car from burning oil.

[JasonGilholme]

Doesn't the engine already have a catch can from factory??

That little black box which is part of the PCV system that sits between your oil filter and transmission.???

[DLO01]

Yes it does. Block > PCV box > PCV valve > Intake manifold.

[dsp26]

^^So the PCV Box drains back to the block? or it gets full hence the requirement for a catch can AFTER the pcv valve?

Whats the point of changing the PCV valve though? no matter what it leaks air one way from PCV box to Plenum(IM).. spring tension just reduces over time... but that doesn't matter coz air path is always towards the plenum...

at idle theres plenty vacuum so othe valves open... but at higher rpm theres less vacuum therefore its really crankcase pressures that force out the blow-by through the PCV...

on a side note i was testing the direction by sucking/blowing through both sides... oil tasts like crap :/

[JasonGilholme]

^^So the PCV Box drains back to the block? or it gets full hence the requirement for a catch can AFTER the pcv valve?

Whats the point of changing the PCV valve though? no matter what it leaks air one way from PCV box to Plenum(IM).. spring tension just reduces over time... but that doesn't matter coz air path is always towards the plenum...

at idle theres plenty vacuum so othe valves open... but at higher rpm theres less vacuum therefore its really crankcase pressures that force out the blow-by through the PCV...

on a side note i was testing the direction by sucking/blowing through both sides... oil tasts like crap :/

Yes it drains back to the block. If you undo and remove the black box you'll see that it actually has a hole about an inch or so wide which goes straight into the crankcase. then theres just the small hose which goes up to the PCV and then to the manifold. :thumbsup:

Oil tastes like crap x 2 lol :thumbsup::thumbsup:

[Limbo]

i was always of the understanding that the oil got burnt once it went to the manifold.
The PCV is a one-way valve???
hence you got a catch can to stop that happening

[dsp26]

^^^ yeah sorta... it goes into the manifold and into the combustion chamber to get burnt... effectively lowering octane rating of fuel mixture....

pcv valve is a one way valve otherwise it'd have no purpose.

catch can i guess catches anything else that the PCV box deosn;t.

but then agin 90% of the catch cans in the market is a useless hollow can like mine which i had to modify....

to effectively seperate oil, the intake of the can needs to have a tube going inside that sits near bottom and the outlet should just be sucking from the top of the can. a mesh or steel wool should be in the middle somewhere to clump the vapours into oil drops and sink back to the bottom instead of just ging back out the outlet which would be purposeless...

though i imagine for the hollow types, it would be better to actually pour some oil into there to begin with... at least SOME of the oil vapours will stick to the oil collection at the bottom before coming back out into the plenum

[JasonGilholme]

Thats interesting, i didn't have a look at the PCV Box while i had it off.

I might take it off again and have a look inside to see whats in there. It felt hollow when i picked it up.

[bennjamin]

guys the black boc you all speak of , is a "oil/air separator".

It , essentially IS a catch can. Oil vapor goes into this , oil sticks to the sides and goes back into the sump/block. Then the vacuum goes up the pipe and to the PCV , which is a degree of OPEN/CLOSED depending on throttle position + load.

Replace your old PCV if you have a older engine dont bother with a catch can unless turboed or serious NA

[dsp26]

Thats interesting, i didn't have a look at the PCV Box while i had it off.

I might take it off again and have a look inside to see whats in there. It felt hollow when i picked it up.

though their hollow.. surely they'd be setup in a way like a bandpass sub box maybe?

i'm not game enough to angle grind mine open.. maybe one day IF it needs changing :p




Replace your old PCV if you have a older engine dont bother with a catch can unless turboed or serious NA
i wouldn't consider mine serious NA but I still get the blowby in my catch setup... and compression tests show my cylinder pressures are still impeccable.. well one cylinder was like 1 point off... but like i said... i like t3h vtak til it falls off looool

[JasonGilholme]

It doesn't need to be angle grinded open. The hole which connects to the crank case is about an inch or more in diameter. Plenty of room to see in with a torch. :thumbsup:

So you reckon the catchcan with some sort of object to break up the direct air flow is a good idea. So it actually catches oil rather then just sitting there doing nothing.

[dsp26]

It doesn't need to be angle grinded open. The hole which connects to the crank case is about an inch or more in diameter. Plenty of room to see in with a torch. :thumbsup:

So you reckon the catchcan with some sort of object to break up the direct air flow is a good idea. So it actually catches oil rather then just sitting there doing nothing.

the THEORY is sound and is why i did it to mine as I remember an article a long time ago that pointed out what a proper catch can looks like (it's one of the name brands). they did a 1 week test on a gtir (notorious for blowby) and achieved better filtering with the expensive catch... i on the other hand bought one of those $50 accessory ones.

Modifications included (in order):
- remove both outlet/inlet nipple
- cut up a hose for the inlet and plug the inlet into the hose
- hosed inlet will no longer fit in the hole of the can, get a drill and make it wider
- get high pressure compressor and blow all the metal shavings out of the can
- get FINE industrial grade steel wool and feed it from the bottom drain hole
- put everything else back in together


Oh and these cheapo catches will cause idle hunt coz of the air leaks.. make sure you tighten all the screwable parts, replace O-rings as neccesary, use those thin nylone sealer tape things on the threads.