Oil catch can/ Breather

[Ta2272]

Hey guys how are you goign i am replacing my old oil catch can with a new one and the new one only has 2 hoses going to it

1 for crank case vent
2 for tapper cover ventilation

i have seen on many other cans that there is a third whole for a breather hole, i am just wondering if you need to have a breather hole on these, this is being installed on my race car so it is important.

thanks alot for your help

Jason

[TurboRA28]

My understanding is the catch cans with the 2 pipes and no breather are designed to work like this..

1 hose from the crankcase vent or rocker cover
1 hose back to the inlet

If you put both hoses to the crankcase and rocker, I can see it just getting pressurised.

You might need to drill a hole in it and add some kind of breather.

Cheers
Joel

[monkeymajik]

I thought crankcase and rocker cover vent refered to the same thing?

If you have two ports or valves on the engine you could join them and connect it to a single port on the can. Then goto the air or inlet.

[The Witzl]

That's exactly what i have done on my 18R-G.

In stock configuration, the crankcase vent on the block goes to the balance chamber after the throttles on the intake.... and the rocker cover vent goes to the air box before the throttles.

I just t-pieced both vents together, then that one line into the catch can.... The other port on the catch can *SHOULD* go to the intake before the throttles, but i've got K&N filters so thats a little difficult to acheive.


I would like to know if what i am doing could possibly be bad in any way??

[craigy]

Bring all of the pipes that you wish to vent into some sought of joiner and connect it to one side of the catch can.

The other side is fed back into to intake (so it burns all of the blow by). If you just drill a hole in the thing it will vent the engine bay causing an residue to form over everything.

I've seen some arrangements where people have tapped a hole in the bottom of the catch can to act as a drain going back into the sump.
The catch can I have has a piece of tube running up the side acting as a indicator so I know when to empty it out.

I done three track days and a heap of spirited road driving over the last few months and its only bout an 1/8th.

Hope this helps

Cheers
Craigy

[Ta2272]

well my old catch can was more or less just a plastic over flow bottle around 2ltrs, it filled 1/4 full from one track day not to mention how much was lost down the side of the car .

i just need a catch can to suit my setup but it is hard to find any, mainly hav ebeen looking on ebay, cams rules also state that it needs to be of 2lt in capacity for my size engine 2ltr.

any ideas on that one?

[Talasas]

I've been running a backyard mechanic job for the last 2 months. Basically I found some longer hose of the same ID as the valve cover breather hose on the 4A-GE, ran this hose to an old water bottle sitting just under the filterbox. The hose sits snugly inside the bottleneck because I sandwiched some scotch brite in there to act as a sort of breather. I check the bottle every second time I drive the car and over the last two months I've had just under a centimetre of oil build up. It may not be much but thinking of all that oil being in my intake is enough to make me shudder.

I'll be buying myself a proper catch can as soon as I can actually find a place that sells them. I think the ones with the breather are much more recommended that say the GReddy ones with only two holes because the oil vapour still just goes back into your intake with the GReddy ones. If you have one with a breather the pressure difference in the atmosphere favours the vapour to want to escape out the breather filter and more oil vapour gets filtered thus cleaner air goes into you intake.

[Biggo]

Autobahn had a cheapie goin for like $50 up here. .5 ltr capacity i think and it didnt look too bad. Might have to get me one for the notorious 4agze befor she starts spewing into my intake.

[ToySprinta]

Unfortunately, i think you can only have a breather on older cars.
I was failed on rego because i just has a breather on the rocker cover. had to route it back into the intake to pass...

[Biggo]

Bummer, yair i think your right about the breather. I was thinking of routing the brake booster into the rocker cover inlet on the intake and putting either a one way filter/valve or oil catch can onto the rocker cover breather.

[MWP]

I would like to know if what i am doing could possibly be bad in any way??

Yup it is....

People need to learn the theory of PCV:
- Removes gasses from the crankcase which can contaminate and shorten the life of engine oil.
- Puts the crankcase under a slight vaccum which helps prevent oil leaks and improves piston ring sealing.
- Stops nasty gasses being vented to the atmosphere.

Whoever came up with the idea of vented oil catch cans should be shot.
To me they look like someones simple way out rather than a well thought out solution.

So, if you want to use a oil catch can, do it right.
Make the can sealed, have two pipes on it, one to a PCV valve on the cam cover, the other to the inlet manifold.
On the bottom of the can, put in a bolt so oil can be emptied now and then.
You should also have a pipe running from before the throttle body (filtered air) to the cam cover as a way for clean air to get into the crankcase.

[The Witzl]

You should also have a pipe running from before the throttle body (filtered air) to the cam cover as a way for clean air to get in.

What for, i dont understand this part?


Agreed though, that a CORRECT oil catch can (or oil/air separator) system should take the PCV gases from the crankcase, route them into an oil/air separator (aka catch can), and then have the gases pass back into the intake of the engine before the throttle butterfly.

the idea of this is that the gases are still taken from the crankcase, but the oil is separated out so as to keep your intake nice and clean and free of oil

I dont get what you mean by this extra pipe though...

[clubagreenie]

To prevent vaccum forming in the crankcase?

All that oil saturated air has to come from somewhere.

[Toobs]

All the oil saturated air is blowby... i.e. air (and fuel) is blown past the rings
I would have thought there would be more than sufficient blowby in most cars to make up for the vacuum created by the intake.

[clubagreenie]

That's what I've had thought but the old 2M in the crown has a large tube with a vent on top for case venting (direct to atmosphere). The 4M had a tube into the bottom of the inlet, but by memory the filler cap wasn't vented on either. So it must be enough, though in the end the 2M still had 130psi compression. It was just in the crank case, not the cylinders.