Engine Crankcase Ventilation and Oil Breather (under Lubrication system)

About Engine Lubrication system:

The crankcase ventilation :

The combustion process result in the production of corrosive gas and water vapors. Some of these get past(below-by) the rings and pistons into the Engine crankcase. If these blow -by vapours condense into liquid from in the crankcase , they mix with engine oil forming a corrosive sludge. The sludge is then circulated with the oil and results in increased corrosion and wear of the engine parts. Present day engines use a positive crankcase ventilation system. Engine vacuum is used to cause a flow of fresh air into the crankcase and removal of blow-by gases from the crankcase.

Most of the combustion blow-by occurs when the combustion chamber pressure reaches a maximum, during the compression and the expansion stroke. At high pressures, the gases leak to the crankcase around the piston rings and through the piston ring gap. The amount of blow-by varies greatly depending on engine design, temperature operating conditions and engine wear.
It is well known that all internal combustion engines (even when new) will have certain amount of blow-by. If it remains stuck in the crankcase, the pressure will increase, which can result in effects like:
➤ The efficiency of scraper rings will be reduced and consumption of oil will increase.
➤ Contamination of oil will increase, more sludge will be formed and engine wear will be more.
➤ Fuel charge will become weak, ignition will be retarded and there will be loss of power.
➤ Blow-by gases will escape through the easiest possible route- filler cap, oil seals.

OIL BREATHER:

An opening called oil breather is provided in the engine lubrication system to the outside air. Its purpose is to prevent building up of excess pressure in the crankcase. Baffles are provided in the oil breather in order to avoid air leaving the crankcase taking lubricating oil with it.