sosonic

Oil catch can vs breather vs breather catch can

I saw a nice looking breather catch can for the mini-cooper and it started me thinking. Which of the 3 was really better and why? Oil catch can, breather, or breather catch can.

Case of each:

1. The oil catch can




The theory for this is that intake vacuum sucks in oil vapors and oil into the catch can. The catch can helps condense a lot of the oil, but vapors and gases may still enter the intake. This method would reduce the problem but not totally eliminate it. Some oil vapors would still make it back into the intake.

Note- a good oil catch can would have baffles to help condense the oil and bad ones would not. For the types without baffles you would need to put some type of steel wool/brillo inside for the purpose. Baffle or no, some oil vapor would get past.

2. The breather or inline oil catch can and breather




Usually is done inline and perhaps with a small catch can in front of it. This would prevent any oil or oil vapor from getting into the intake, but the problem is vacuum necessary for "blow back" oil coming from the oil filler pipe? Other issues are using too small of an inline catch can and too much oil get into it. The other problem is excessive oil vapor being vented by the breather.

3. Breather catch can






This seems to be the best of both worlds. It will help condense larger oil vapor, oily gasses would be expelled by the breather, and all this would be done with the aid of vacuum pressure from the intake. In theory, the breather catch can would have "cleaned" the air going into the intake so that very little vapor would be there.

However what do you guys think about number 3?

Note: Oil Catch Can of any type is not required for Series II's 2009-2012.

r0tor

iTrader: (1)

unless there is a check valve in that breather, #3 looks like a giant vacuum leak

sosonic

I'm looking into this about the check valve. I see what you mean, suction from the intake could cause a "reverse flow" from the small air filter thus a giant vacuum leak.

The breather catch can would have to be constructed to allow only flow from the oil filler piper > to catch can > to breather or to intake.

The breather/filter should only "exhale"/push out vapor and never inhale/suck air or it is worthless.

MazdaManiac

iTrader: (3)

No vacuum leak.
The catch can is vented pre-MAF on a recirculating setup.
If you just do a vented can (like most people), you are just ventilating the "crankcase", which isn't under vacuum to begin with.

Because of the way the Renesis ventilates, you don't need anything more. You just want to catch the oily water vapor that boils out of the pan.

Spinning Sushi

iTrader: (21)

You only need an oil catch can or breather if you drive an 04 or 05.

MazdaManiac

iTrader: (3)

Right, because if you drive an '06 or later (or have had the TSB countermeasure installed), the crap from your crankcase goes directly into the upper intake manifold and sh*ts on your motor more completely.

sosonic

Totally agree. Rather have "clean" air going into my intake and crap from my crankcase going some other place than my intake or upper intake manifold.

I have a catch can and breather. But, the idea of a breather catch can is intriguing. If it works, seems like it might have been the way to go.

Bester

Yea,...been thinking about this. I have an 07. And the hose routing looks like it dumps the fumes in the two primary intake runners. Well I dont like the idea of oil coating the intake runners over the years,....so I am considering adding a catch can of some sort. This newer setup looks like it would cause a vacuum leak if I simply added a breather (hoses feed intake manifold versus intake tube). Or I am missing something here.

Razz1

Don't need the can just a filter and a plug into the intake.

Check the DIY section.

MazdaManiac

iTrader: (3)

Only if you want an oily little filter dripping on your alternator.

Rhythmic

MM, what's your catch can/breather setup? Any pics? Suggestions?

I'm really considering doing this, especially because the other day I had a BIG oil blowback/overflow issue into my intake.

It happened (I think) when I accelerated briskly up to about 7000-7500 rpm and held it there for a few seconds. I went to check my oil level after I got home and found oil had blown all over the place, and was running down my intake tube and out the filter (K&N v.2 intake).

The weird part was that my oil level was barely at the full mark-not overfilled at all.

MazdaManiac

iTrader: (3)

This is what I got going on at the moment:

mysql

I have a breather on the end of my catch can too. It's been this way for a long time, there haven't been any issues with the engine bay getting dirty.

NgoRX8

iTrader: (1)

MM, is your catch can vented and running only from the oil filler neck?

would you suggest this method or having a sealed can running from both intake and oil filler neck?

Razz1

Depends upon where and how you mount it.

You can alwayes get a longer hose or an extension to make it hang down the side of the engine.

Spinning Sushi

iTrader: (21)

I've been reading up and doing alot of research on oil catch cans and I believe that running it back into the intake would be the best choice.

Reason:
The catch can will catch all the oil but the oil fumes will go back into the intake and can also grease up parts the throttle body. It has other advantages as well... mostly serve as lubrication though. Hell, it might be good for our apex seals as well!

MazdaManiac

iTrader: (3)

Then why use the catch can at all? This is exactly what we are trying to avoid!

Spinning Sushi

iTrader: (21)

I'm talking about catching the blow back oil itself, not the fumes.

MazdaManiac

iTrader: (3)

You don't want ANY of that going through your intake.

mysql

I actually did that once. The result isn't as you'd expect. As oil drips, the air passing under the car pushes the oil up and you end up with the bottom of your car slick with oil. Not really the best solution.

Razz1

That's why you still need to use a filter.

I actuality mine has barley turned color in over a year. Of cource I only put on about 4k miles, it has seen several track days.

It's not like oil gushes out of the fill pipe into the intake.

Rhythmic

I with that were true. See my previous post.

I've looked at a few catch cans online (ebay, etc.) and I can't find one that has a breather on it, like MM's. Anybody know where to find one, hopefully for a decent price?

mysql

you don't buy a catch can with a breather.

you buy a catch can, and instead of connecting one end to the intake, you buy a breather filter at your local auto store and install that instead.

tdiddy

The Mazsport Oil Catch Tank doesn't have a breather "nipple/port" on it. I never asked why.

Rhythmic

thank you, sir.