How Do Car Engine Lifters Work?

The lifters actuate the intake and exhaust valves. The cam has lobes that are egg-shaped, allowing the lifters to move up and down. The heel of the cam is the short, wide end of the lobe. When the cam turns, it pushes the lifters up and down, and in turn, the lifters move the valves into an open or closed position. In the case of non-overhead cam engines, the lifters move a push rod up and down, which in turn moves the rocker up and down. The front of the rocker moves the valve.

Solid lifters do not compress, as hydraulic lifters do. If your vehicle has solid lifters (normally found in racing applications), you must adjust the lifters periodically in order to maintain the proper tolerances (these are different, depending on the year, make and model of the vehicle).

Hydraulic lifters do not need adjustments. They are "pumped up" with oil prior to installation in the vehicle. Hydraulic lifters contain more separate pieces than a solid lifters. They have a plunger and a spring that is contained within the lifter body. The plunger has an oil reservoir, which is kept full through a check valve. If oil pressure becomes low, the lifters may not get enough oil and will become noisy or cease working.

Roller lifters are another kind of lifter. These are hydraulic lifters with a roller on one end. On both overhead- and non-overhead cam engines, the roller rides directly on the camshaft. This allows for less resistance, which in turn allows for more horsepower.