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Crankcase Breather
johnwilders - 22/3/13 at 10:23 PM

Hi all.
Why is a rocker cover breather needed in a cross flow, surely it could do all its breathing through the crankcase breather, mine has a mesh vented cap but I want to get rid of it. My thinking is if I have a catch tank mounted as high as it can be and filled with mesh with the breather entering the base and venting through a pipe at the top the oil caught would drain back to the sump when its not running.

snapper - 23/3/13 at 05:10 AM

Breather pipe to the base would fill with oil and foam up like bubble bath
Your trying to vent through the oil
Best to pipe to the top and drain through the bottom

big-vee-twin - 23/3/13 at 07:58 AM

Have a look through this link

johnemms - 23/3/13 at 02:29 PM

I have pipe from crank to rocker cover .
Then a pipe from rocker to a catch tank.
All good

Cured oil surge by moving oil pick from rear of engine up to front end of sump..
All good

MikeRJ - 23/3/13 at 02:53 PM

quote:
Originally posted by johnwilders
Hi all.
Why is a rocker cover breather needed in a cross flow, surely it could do all its breathing through the crankcase breather,


It seems logical I agree, but if you remove the remove the rocker cover vent I can almost guarantee you will get excessive crankcase pressure and lots of oil forced through the crank case breather. A well proven way to arrange the breathers on an xflow is to connect the crankcase breather to the rocker cover, and then from the rocker cover to the catch tank. You don't have to use the vented oil cap, you could weld in a suitable bit of steel pipe to attach a rubber breather pipe, but make sure there is a splash guard behind the opening to minimize any oil getting into the breather.

[Edited on 23/3/13 by MikeRJ]