The crankcase is a component of the internal combustion engine that houses the crankshaft. It is located under the cylinder. While it is sometimes a solo component, mostly it is integrated to the cylinder bank to form the engine block. Crankcase refers to the whole area around the crankshaft.
If you need 5-Star emissions service in Phoenix, call us now for a FREE check-up:
Like other components of the engine, the crankcase is built through sand casting. It is actually made of cast iron or aluminum. These materials are strong and hence can withstand normal engine operations. Often, crankcase has a hole at the bottom which connected to the oil pan by a bolted joint gasket.
Some crankcase design encompasses the entire main bearing of the crank. In other designs, they form one half and bearing cap completes the other half. Similarly, some crankcase models use oil pan structural strength while others do not require it. Crankcase and oil pan are reinforced using ribs and bosses. Apart from housing the crankshaft and connecting rods, other functions of the crankcase include:
- Containing motor oil
- Firmly joining the engine to the transmission
- Forming part of the vehicle frame, i.e., in tractors
In a two-stroke engine, the crankcase is used as a chamber for fuel-air mixture pressurization. In a four-stroke engine, the crankcase is used to store and circulate oil. Pistons are used to seal the crankcase. In four stroke engines, a small amount of pressure in the crankcase proves to be helpful as it keeps out harmful objects and keeps the oil well situated.
Crankcase Ventilation System (CVS)
CSV is a pressure sensitive, one-way passage that controls gases leaving the crankcase. When the combustion products from the combustion chamber blow past the piston rings into the housing of the rotating assembly, the result is referred to as blow by. If the blow dry is not ventilated it condenses and mixes with oil vapor. The mixture forms sludge or dilutes the oil with unburned gases.
Excess crankcase pressure can cause oil leaks in the engine past the gaskets, engine seals and crankshaft seals. This is why the crankcase ventilation system is very important. It vents blow-by gases out of the crankcase through Positive crankcase ventilation (PVC) valve. Ventilations re-circulate the gases before being removed through the exhaust tailpipe. This method is called closed-loop CVS and it significantly reduces emissions. On the flips side, open loop CVS release blow-by gases to the atmospheres directly via a filter.
Read more about your car’s emission system: