GMC 476525 Push Rod

Valve mechanism components must be reinstalled to their original positions, and all removed components should be placed in a compartmented box for identification. Begin by removing the rocker arm cover. If only the pushrod is being replaced, loosen the rocker nut/bolts enough to rotate the rocker arm away from the pushrod. For replacing the rocker arm or valve spring, remove the rocker arm nut and ball, then lift off the rocker arm. Pull the pushrod out of its hole, and if the valve spring is to be removed, take out the spark plug from the cylinder being serviced. To keep the valve in place while removing the valve spring, use compressed air by attaching an air hose adapter to the spark plug hole, or if compressed air is unavailable, bring the piston to approximately 45-degrees before top dead center and feed a long piece of 1/4-inch nylon cord into the combustion chamber, leaving the end hanging out for easy removal. On early models, thread the rocker arm nut onto the rocker arm stud, position a valve spring compressor tool over the spring, and apply downward pressure to compress it. On later L4 models, install the rocker arm bolt and use a lever-type tool for compression. Compress the spring just enough to remove the valve spring retaining cups, then release the pressure. Remove the valve spring retainer, cup shield, valve spring, and valve stem oil seal, which must always be replaced when the spring locks are disturbed. Installation follows the reverse of removal, ensuring to coat the bearing surfaces of the rocker arms and balls with 'Molykote' or an equivalent before installing the rocker arms. The L4 engine valve mechanisms do not require special lash adjustment, while V6 engines necessitate lash adjustment.