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.
Very useful to know and well explained!
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