Hydraulic valve lifters maintain a constant adjustment in the moving parts of a valve train. During engine operation, this clearance is required to prevent the valves from being held open and damaged due to thermal expansion. During operation, the lifter's internal check ball is constantly working with the weak actuator spring to maintain a zero clearance in the valves. Adjusting a hydraulic valve lifter is a simple process that is usually done only once during the life of the engine.
Remove the valve covers and the spark plugs. Number the spark plug wires to ensure they are put back in the correct location later. Removing the spark plugs makes it easier to turn the engine by hand and prevents the motor from drifting due to residual cylinder pressures.
Rotate the engine by hand in the direction of normal operation until the number one cylinder exhaust valve rocker arm begins to move from the closed position to open. Locate the number one cylinder intake valve rocker arm.
Loosen the number one intake rocker arm adjustment lock-nut and turn the rocker arm adjuster screw until clearance can be felt between the rocker arm and the push rod. Tighten the rocker arm adjuster screw slowly until the adjuster just seats on the push rod. Tighten the rocker arm adjuster screw 3/4 of a turn and fasten into place with the lock-nut.
Rotate the engine until the number one cylinder intake valve opens and just starts to close. Repeat Step 3 to adjust the number one exhaust valve.
Repeat Steps 2 to 4 for each cylinder. Be sure to adjust each cylinder sequentially so that no valve is missed. You can follow the firing order, the cylinder numberings, or engine sides. A paint mark may be used to identify the lifters that have already been adjusted.
Replace the valve covers using new gaskets. Replace the spark plugs, spark plug wires and any other components removed to gain access to the valve lifters. Start the engine and listen for noise in the valve train. Properly adjusted hydraulic valve lifters should be silent.
