Oil pump is needed to make sure the engine oil reaches all moving parts that require lubrication during an engine’s operation.Most modern engines have a wet sump (a reservoir of oil beneath the crank shaft), which is where the oil pump is installed.Oil is supplied to the pump via the oil filter, which catches any stray particles, such as swarf, which would damage the pump.From the pump, the oil travels around the engine via channels, grooves and holes to lubricate the cam bearings and crankshaft, while the crankshaft itself will send oil up to the base of the pistons and lubricate the piston rings.Oil is also needed at the top of the engine, to lubricate the lifters, rocker arms and valve stems and springs.

A vacuum pump, in general, is an added benefit to any engine that is high performance enough to create a significant amount of blow-by. A vacuum pump will, in general, add some horse power, increase engine life, keep oil cleaner for longer.A vacuum pump has the inlet hooked up to one or both valve covers, sometimes the valley pan. It SUCKS the air from the engine, thus reducing the air pressure build up created by blow due to combustion gases going past the piston rings into the pan. Vacuum pumps vary in the amount of air volume (CFM) they can suck so the potential VACUUM a pump can create is LIMITED by the amount of air it can flow (CFM). The exhaust from the vacuum pump is sent to a BREATHER tank with a filter on the top, which is intended to retain any fluids (moisture, unspent fuel, air born oil) sucked from the engine. Exhaust air goes to the atmosphere thru the air filter.

A tandem pump can be simply described as a low pressure fuel pump in a diesel engine which also includes a vacuum pump. They are used on engins with unit injectors and supply the fuel to the units.It is called a tandem pump because it has two functions: the first function is to act as the vacuum pump for the brake servo and the control circuits for the turbo and EGR, the second function is to supply fuel at approximately 8 to 8.5 bar to the galleries in the cylinder head and to the fuel injectors. The injectors are there to pressurise the fuel to very high pressure (2200 bar approx).

A water pump in a car is a component of the vehicle's cooling system that circulates coolant through the engine to help regulate its temperature. The water pump is near the block's front, and the engine’s belts typically drive it. The water pump plays a critical role in maintaining the engine's proper operating temperature; if it fails, the engine can become damaged or seized.

A starter ring gear is a part attached to an internal combustion engine that is part of the assembly which transfers the torque from the starter motor to the engine's crankshaft, in order to start the engine. Starter ring gears are attached to either the flywheel or the flexplate of an engine. The teeth of the ring gear are driven by the smaller gear (known as the pinion) of the starter motor. The pinion engages the starter ring only during starting and once the engine is running the pinion withdraws.