The valve train is made up of several parts which work together to open and close the intake and exhaust valves in the cylinder head. The hydraulic lifter plays a crucial part in this system, essentially functioning to enable the camshaft to manage the poppet valves. The hydraulic lifter is a self adjusting part, which uses the hydraulic pressure of engine oil to open and close the engine valves situated on the cylinders.

Located in the engine between the camshaft and each engine valve, and powered by the camshaft, the hydraulic lifter is a steel bullet-like cylindrical rod/tube comprising of a piston inside, loaded with a spring mechanism.

The <Model> hydraulic lifter is filled with oil which is pressurised inside the body of the lifter. As it rotates, the lobes on the camshaft make contact with the hydraulic lifter, which opens the engine valves and as the lobes spin away from the hydraulic lifter the engine valves shut again. The hydraulic lifter basically applies the rotational motion of the camshaft to the engine valve, usually via a pushrod which either opens or closes the valve with the aid of a rocker shaft. When the engine valve is closed, the hydraulic lifter is refilled with oil through an oil channel in the body of the hydraulic lifter. The hydraulic lifter reduces engine noise and improves the performance of the engine by reducing the slack, or space between the components, in the valve train. This helps to reduce wear and tear on engine components, enabling the engine to work as efficiently as possible, while increasing the working life of the engine. 

Valves can get clogged up and stick which will cause this part to stop working properly. A tell tale sign of a faulty hydraulic lifter is a distinctive tapping noise in the engine. Regular oil changes will prevent this part from getting dirty inside and ensure it lasts longer. Using the wrong grade oil in the engine can also damage the hydraulic lifter. The tapping sound that usually indicates a fault with the hydraulic lifter, is caused by a loss of internal oil pressure. If a faulty hydraulic lifter is left ignored this can lead to a damaged rocker arm, valve tip and push rod so it's a good idea to replace a malfunctioning hydraulic lifter as soon as possible. The hydraulic lifter, specifically designed for the make and model of your car, is the ideal replacement part.