oil catch can, does it need a breather?

[vr4boy]

i have got an oil catch can for my levin (silvertop), going to plum it up to the two breathers off the rocker cover, the can dosnt have a breather, so im wondering do i need to mod it and add one to it?

Thanks
Dan

[iOnic]

Yes it needs a breather.

[evil_si]

Ahh yes it does or the crankcase wont be able to breathe, and start killing crank and cam seals, pushing the dip stick out etc

[vr4boy]

cool thanks guys, ill get it modified with a breather on it.

[Mr Ree]

Best to run it back into the intake pipe so it has vacuum on it, putting a filter on the end isnt helping anything really.

[jaypines]

what you got is a single catch can... for steet purposes that almost everytime sees vacuum, you should just plumb it inline with the PCV valve.

[Crucible]

Best to run it back into the intake pipe so it has vacuum on it, putting a filter on the end isnt helping anything really.

IMO, The only downfall of plumbing it back into the intake is oil fumes sludging up the inside of the manifold. Hot oily gases entering combustion chamber can also increase chances of knock.

Thats why some prefer a baffled catch can or remote breather which is totally seperate from intake. C/C Filters are known to block like you say which is why a well baffled 'open' can would probley be better.

[Mr Ree]

I hear you mate, but there shouldnt be much oil going back into the intake manifold if the engine is healthy.

I have had one of those little filters on the exhuast cam cover of my na-t for 12,000 kms and there isnt a trace of oil on it, so I have no reservations plumbing it back into the intake once I finish my cold airbox, but if it was leaving an oily film all around it, I would do as you suggested and run a baffled can to avoid the compressor wheel being sprayed with crap.

My only concern with that though, is having no vacuum pulling on it.

[Crucible]

^ Ahh im with you now mate.

youre talking about plumbing it to intake/vac side of turbo, i read it wrong. thought you meant at intake manifold.

[Heylin]

On my MR2 I ran a closed catch can but also ran a washable inline racing fuel filter onthe line back to the intake (8mm nipples on it)

Gave me the required vacume and also acted as a secondary filter.

Cans with built in mesh screens \ chambers also achieve the same effect.

I never really thought vacume was required, and that the blow by would create enough pressure to push out.

If you look at where it plumbs back into the factory intake (on the MR2 anyway) the metal tube has a slash cut in it and sits in the air stream to create a venturi effect, thus maximising the amount of vac\pull on that line.

[gt4dude]

I have replaced factory PCV and breather port with dash -10 weld on bungs and they go to my can here. the return line from the factory catch can is replaced by dash -6 pushlock hose to the bottom of the can

its only a 12mm filter on top though, should I have bigger port and filter?

[allencr]

its only a 12mm filter on top though, should I have bigger port and filter?

The worse the blowby, the bigger the lines. How's yours?
The filter is unnecessary & does nothing except catch oil vapor, clog up and keep the surrounding area clean, nothing to enhance performance.

[gt4dude]

the factory catch can had a 16 or 17mm breather line back to the intake.

the ID of my breather now is about 10 or 11mm at best

and yes, that is precisely what the filter is for, that and so i dont get drops of shit into my oil.

the main thing for me is keeping the gritty oil crap out of my turbo, intercooler, blow off valve, throttlebody, inlet manifold, sensors, idle valve, etc

i was just wondering if the 12mm breather was going to be too small, i can easily get a bigger bung welded on, its just that was the only filter i had at the time the cans were made.

RE: clog up - the hose clamp isnt done up tight on the filter, so if it does clog up that bad (which it never does), the filter and the dip stick should just pop out

[Mr Ree]

Is your tank baffled?

I filled my old one with a 3 pack of steel wool to ensure all condensation and oil residue was captured, rather than fired into the compressor wheel etc.