crankcase breather

[jamman18]

Just wondering what the crankcase breather tube's purpose is.....in other words, mine came off and I want to know what happens if I don't put it back on?  I'm going to regardless, but just wondering as I can't find much info on it.

[Lucky 1]

There are two openings on the engine.
One is on the bottom back of the engine crankcase.
The other one is at the top of the cylinder head.

The one on the TOP of the engine is the breather.
The air that gets trapped under the pistons as they
go downwards needs to escape,
 and so the breather gets rid of that pressure or
the seals on your engine would leak and get blown out.

The one on the BOTTOM of the engine is where oil and oily fumes gets returned to.
When your oil in your oil tank sloshes around it can spill over even though there is a baffle.
Also there are hot oily fumes trying to escape.
Those fumes and oil go back to the engine through hose connected to the back of the engine.

There is a law of physics that says you cannot compress a fluid.

if you try to stop a fluid under pressure it can be so strong that it can
 push seals out, or even break metal parts.

[shinyribs]

Short answer: keeps you engine from slobbering oil all over itself and prevents dirt from having a direct path into your engine. :)

[jamman18]

Thanks guys!