The oil/air separator is the one usually referred to as the catch can as it 'catchs' the oil vapour in the air from the crankcase before being sucked into the engine.
The catch can should be sealed unit (i.e. no filter on it venting to atmosphere). Usually an oil/air separator has two pipes, one inlet (the lower on the can) and one outlet (the higher on the can).
The internals of good a catch can are divided into two main sections, a small air cavity at the top separated by a perforated plate from the bottom section. The bottom section is filled with a gauze (eg very fine stainless steel wool) that helps to separate the oil vapour from the air. The pipe from the crankcase enters into the gauze filled area. The pipe back to inlet pulls air from the small cavity in the top of the catch can. There is also a drain cock on the bottom of the can to drain built up oil.
There are other catch cans about that dont have the two chambers and are simply made up of a small cylinder. There are also some on EBAY with a little level thingy on the side to show how much oil is in the catch can.
Sun, 04 April 2004 12:27
