As the Mazda engine operates, it keeps on burning fuel in the combustion chamber. Among the products when burning fuel are the gases which are pushed out into the exhaust valve that is located above the combustion chamber. These will then proceed to the exhaust manifold, throughout the exhaust pipes, and through the tail pipe into the surrounding atmosphere. This is the ideal direction of the gases produced in the combustion chamber as they are routed out. However, there are some of these gases which leak past the piston rings and toward the crankcase of the engine. These gases are referred to as 'blow by' gases because the pressure blows them by the piston. In reality, these are harmful gases because they are in the nature of hydrocarbons and are detrimental to the Mazda engine. They are unburned fuel and contain carbon dioxide and a significant amount of water vapor. When allowed to stay in the crankcase, they become too concentrated and condense, forming corrosive acids and sludge in the engine's interior surface. These are harmful to the engine because they tend to clog small inner passages, which eventually cause overheating. This condition also results to poor lubrication and high emission levels. To keep the Mazda crankcase clean as much as possible, a Mazda PCV Valve is attached to it so that the 'blow by' gases can escape from the crankcase. PCV valve stands for Positive Crankcase Ventilation valve, the one that ensures continual refreshment of air inside the crankcase.
One part of the PCV system is the PCV valve which gives the engine a path where the crankcase combustion gases can be returned to the intake manifold so that they can reenter the combustion chamber as part of the fresh charge of air and fuel. A small percentage of air in the intake manifold is diverted by the PCV system into the crankcase via the breather. However, this is allowed to be drawn back again in the intake manifold. This is actually a process of flushing out contaminants from the crankcase and into the combustion chamber. When the engine is running, the pressure in the intake manifold is less than the pressure in the crankcase. This will allow for the air from the crankcase to move towards the intake manifold via the breather. The Mazda PCV Valve is in partner with the breather tube in maintaining air inside the crankcase. The breather tube connects the crankcase to a clean source of air which is usually the air cleaner body. Before reaching the breather tube, the air passes through a screen, baffle, and other simple systems to arrest its flame front which can become explosive inside the crankcase as it can be ignited by a back fire.
The baffle, filter, or screen is able to trap oil mist that can be kept inside the engine. As the air circulates inside the engine, it picks up and clears away combustion by-products such as hydrocarbon and water vapor. After collecting these unwanted compounds in the crankcase, it will exit in the baffle, screen, or mesh so that oil droplets can be trapped before going to the Mazda PCV valve and towards the intake manifold where it will combine with the fuel.