A valve lifter is a component located deep inside your engine that serves to transfer the motion of the camshaft through the valve system (the “valvetrain”) to an intake valve or exhaust valve. Each valve has a corresponding lifter, and there are anywhere from eight to thirty two valves in an engine. The lifter also serves to take up slack in the valve train.
Depending on the configuration of your specific engine, the valve lifters might roll directly on the camshaft lobes, or they may be mounted in the cylinder head and simply provide a fulcrum on which the rocker arms that actuate the valves can pivot. Modern hydraulic valve lifters are pressurized with engine oil when the engine is running, creating a hydraulic “cushion” for the other parts of the valvetrain. This serves to adjust for changes in engine temperature. Tolerances in the valvetrain must be maintained correctly to eliminate excessive wear and noise, and to ensure correct valve geometry.
A valve lifter is an essential part of valve timing in your engine. The camshaft(s) rotates in relationship with the engine’s camshaft and acts as the conductor for the symphony of activity in the valves. Asymmetrical lobes placed at specific locations on the camshaft allow the intake valves and exhaust valves to open and close in concert with the movement of the pistons during the combustion process. If any of the components in the valvetrain - the valves, pushrods, rocker arms, or the lifters - are unable to perform their parts, engine performance will suffer.
Signs that the lifters are going bad include: