Oil Catch Cans
 

The flow circuit of hoses to an oil catch can, theres three hoses, what do they all do?

Should the circuit be pressurised at all? I understand that when pistons/blocks are worn that the cylinder pressure leakage past the pistons will pressurise the oil cranckcase circuit but is there any other areas that may create some slight positive pressure?

only atmosphere positive when vacuum is created by the PCV.

[QUOTE=atz 242]The flow circuit of hoses to an oil catch can, theres three hoses, what do they all do??[/QUOTE]

i have 4 hoses coming out of mine, wheres the forrth on mine go?...unable to go look at it atm.

i have 2 on mine.. ??

[QUOTE=tuna]only atmosphere positive when vacuum is created by the PCV.[/QUOTE]
so the crankcase is "always" at atmos pressure? Otherwise you would blow out your dipstick ey..

How does the pcv work? Whats it for?

the pcv vavle pete directs unburnt blowby gas back into the intake manifold (under the throttle body on rexies)

yeh the pcv is a one way check valve that opens up on throttle off (manifold vacuum) and sucks the vapour through the catch can out of the crank case/cam cases, under usual circumstances the catchcan should filter the oil vapour and should allow enough air flow to allow the PCV to pull a vacuum on the catch can to evac the excess vapour out of the casings.

without the catch can the oil vapour is pulled directly into the motor, and with factory plumbing, theres a vacuum point on the turbo inlet, which allows the turbo to practically suck the guts out of the crank/cam cases when comming on boost, this in effect causes oil vapour to get into the combustion process and further cause detonation.

ahh cool, recently emptied my catch can, had some foul gunk in it! but not much, prolly 50mls?

Anyway, I packed some steel wool in it to see if that would aid actually "catching" the oil before it goes strait out..Was sometimes getting oil out of the airfilter on the top!? and sometimes hoses coming off it. Prolly just engine movement as none had clamps on them and some were a bit loose.

So, now their all clamped, steel wool installed, half a tank of spirited driving and not a drop of oil to be seen anywhere. :)

instead of steel wool,
try metal scourer pads, you dont want wool fibres getting sucked back into the engine :)

it would be going into where? It would collect in the sump I spose and should drain out on oil change?

I'm pretty sure it's not going to get sucked thru, didnt pack the can full, especially once a bit of oil vapour coats it all.

the can is a bit bodgy, can't really get the stuff out without cutting the can open, stuffed the wool through the filter hole in the top..