Any engine that burns gasoline will emit excess gases. Besides being harmful to the environment, residues from these gases eventually condense into corrosive materials. After a while, these materials begin to clog the engine and cause overheating and excess emissions. Small engine breathers solve this problem by redirecting gases so they don't get a chance to settle within the engine's interior. Also known as a "positive crankcase ventilation valve" or PCV valve, the basic design acts as a one-way mechanism that works to protect the contents of the crankcase. Though it's small, its ongoing operation goes a long way toward prolonging the life of a small engine. Preventative maintenance steps should incorporate a routine breather inspection, along with tune-ups, seal inspections and cooling system adjustments.
Although small engine breathers help keep engine components clean, they also help to reduce any pressure that may build up inside of the engine. Hot engine oils and exhaust gas from the piston rings produce vapors that increase the pressure inside the crankcase. A breather device relies on the low-pressure area created by the intake manifold to pull excess gases from the breather and through the crankcase. From there, the gases are diluted and recombine with the gases inside the combustion chamber. Because pressure buildups most affect the areas with the least resistance, seal damage and poor piston performance can result. This leads to more serious problems down the road. Besides providing ongoing engine support, breathers are an eco-friendly solution because harmful byproducts are redirected through the engine's combustion chamber rather than emitted into the surrounding environment.
When small engine breathers start to wear out, overall engine performance will decline. The actual location of the breather may vary a bit depending on the type of engine you have. Machinery such as lawn mowers have a breather tube that runs from the crankcase to the back of the air filter holder. Problems including white or blue smoke exhaust may be caused by built-up pressure that's forcing oil through the cylinder. This can indicate a breather that's clogged or not working at all. Loss of engine power can be the result of leaky seals impairing the combustion process. A faulty breather will allow excess residues or sludge to accumulate within the crankcase area. After a while, these residues can form corrosive acids that damage the engine's interior surfaces. Other issues may be contributing to a known problem. However, the breather is always a good place to start.