# What is a "Breather tube/valve" on a 4.5hp Tecumseh engine



## nopoles (Jun 1, 2016)

Hello,

My lawn mower recently died. I didn't want to buy a new one, so I found a used one real cheap that runs but needed a little tuning. After a quick cleaning of the carburetor and air filter I was easily able to mow my lawn. I figure some fresh oil, gas and a blade sharpening and I'd be good to go for a while. 

However while working on the carb I noticed something very odd. It seems the Breather Tube inlet at the carb was plugged with a woodworking screw (!!). See below:

imgur.com/LdqVDET

Best I can tell from research online is there should be a tube that connects to a Breather valve on the engine. I guess at some point the tube came loose or fell off and the previous owner plugged this with a screw. 

Like I said, the mower worked and I spent 45 minutes doing my lawn. However I'd like to fix this. I found the tube online, so assuming the valve is still on the engine I should just have to install this and I'm good to go: 

searspartsdirect.com/tecumseh-all-products-parts/36775/0071/143/model-LEV100335028D/1068/1503500.html

I know basically nothing about motors and I'm now really curious... What is a Breather valve and why on earth is this working without it? And is there any harm in not replacing this immediately? 

Thanks


----------



## nopoles (Jun 1, 2016)

I may have finally found the answer myself:

aa1car.com/library/pcv.htm

Fuel can leak past the piston rings into the crank case. It shouldn't be there and needs to be vented. The valve allows the excess fuel to escape, and it's connected to the carburetor so the fuel can sent back into the system instead of leaking into the environment. 

I suppose plugging the intake in the carburator with the screw will allow the system to work, but the excess fuel is instead just leeking out. It's not required for the engine to work normally, it's just there to make the engine run cleaner. I'm not sure what fixing the tube will do to the engine performance, but I think I understand why it still works.


----------

