Small engine question: what in heck is a crankcase breather?

[Zack]

I previously thought the tube that comes from beside the muffler to into the carburetor (before the choke) was an exhaust-recycler, but obviously not. "Reading the f***ing manual" revealed that it was really a crankcase breather, whatever the heck that is.
This engine has a vertical crankshaft. In the compartment that you open up to service valve stems/springs, the plate that unscrews is the crankcase breather. There's oil for some reason in the compartment, btw.
Anyway, the breather is a thick thing that comes off, and it has a hole into it that opens into the compartment. Then there's a tube that attaches to it and leads to the carburetor, after the air filter and before the choke.
So! What's a crankcase breather, how does it work, etc. etc. etc...

[Dr_Davenstein]

Well, on older V8 Chevrolet engines, there are tubes going from both vavle covers to the carburetor. i've been taught to call it a blow by valve. All I know is that's it's another way to reduce the total emissions from the engine... a sort of optimization technique.

I could be totally wrong though... well, the people who taught me this stuff coud be wrong.

Anyway, going on gut instinct...
I would say that every engine needs some kind of crankcase breather. The engine builds up heat no matter what. Water makes steam , Oil makes smoke...Where is it going to go if there is no way for it to escape? It would eventualy blow the gaskets... or the engine itself would explode! :rotfl: