The engine crankcase consists of two parts: the upper and lower. The upper part of the crankcase is cast integrally with the cylinder block. Crankshaft, camshaft and other units and parts of engine are installing into the upper part of crankcase.
The lower half of the crankcase protects the parts of the crank mechanism and valve mechanism from contamination, and is also used as a reservoir for engine oil. Therefore, the lower half of the crankcase is often called oil pan.
Oil pan Construction
1 – Oil pan; 2 – flange; 3 – gasket; 4 – partitions; 5 – copper asbestos gasket; 6 – drain plug.
Oil pan closes the cylinder block from the road. There are horizontal and vertical partitions 4 are installed inside the oil pan 1, which delay the movement of oil waves and protect the crankcase seals from oil shocks. There is a drain hole closed by a stopper 6 in the oil pan.
For a tight connection between the cylinder block and the pan flange, a gasket is installed. The cylinder block connector plane may extend along the axis of the crankshaft. However, in most engines it is shifted down to increase the rigidity of the upper half of the crankcase.