Wet Sump

The oil sump, or oil reservoir, is the part at the bottom of the engine, at the lowest part of the engine, and is responsible for supplying oil to the engine. It consists of a drain plug with a magnet, a gasket, a trough and screws. They are available in different sizes for a specific car and usually depend on the displacement and power of the car.

Purpose of the wet (oil) sump

The design and purpose of the sump depends on the type of lubrication system. The sump is part of a four-stroke engine with a typical wet sump lubrication system. The crankcase contains the oil needed to lubricate the engine, which is distributed by a lubrication pump to all friction points of the engine. This ensures smooth and efficient operation. In a passenger car, the sump normally holds between 2 and 8 litres. During operation, the crankcase also acts as an oil cooler, which is why some crankcases are fitted with cooling fins.

The crankcase may be made of aluminium or solid steel. The advantage of steel is its strength, so it tends to withstand the impact of pebbles, the disadvantage is that it tends to corrode. Aluminium is not rustproof, but it is less robust and rather soft, so pebbles and various bruises cause dents in the aluminium crankcase.

Wet sump faults

This is normally a long-lasting and reliable part that does not need to be replaced regularly. The main reason for replacing a sump is mechanical damage. This is influenced by the position of the sump in the car, as it is quite low, so there is a high risk of damage to the sump when the car is low and off-roading. The crankcase must be replaced in the event of mechanical damage, corrosion and severe deformation of the part, which may have been caused by the engine overheating. 

The most common failure of the crankcase is puncture. It can be punctured quite easily by running over a stone or hitting a pothole, which are the most common factors in off-road driving on poor roads. A punctured sump is immediately indicated by an oil pressure light on the dashboard. There is also a shock and a clear oil leak. If the crankcase is damaged, the engine must be stopped as soon as possible and the engine must be stopped. Oil usually drains quite quickly after damage, and an engine running without oil can "seize" in a matter of minutes. 

Less commonly, however, crankcase failures can also be caused by corrosion, which leads to holes. Also, tightening the drain screw too tightly can damage the threads, leading to oil leaks. Also the gasket, through which leakage can occur. In some cases, it is not necessary to replace the entire sump, but only certain parts of the sump need to be replaced. Oil leakage also endangers the performance of the engine and other parts, and is dangerous for the environment. 

Should I repair or replace the oil sump?

If the damage to the sump is extremely serious, it must be replaced. In some cases, threads and gaskets can be replaced without having to replace the entire sump. Some drivers simply glue the holes in the crankcase, but this does not prevent the crankcase from leaking oil and re-piercing, so repairing the damage will not help.