For models from 1985 through 1999, begin by detaching the rocker arm cover(s) from the cylinder head(s) and loosening the rocker arm stud nuts, storing them in marked containers for reinstallation. If only the pushrods are being removed, loosen the nuts enough to rotate the rocker arms aside. Lift off the rocker arms and pivot balls, storing them with the nuts, and remove the pushrods, keeping them separate to avoid mixing. Inspect each rocker arm for wear and damage, ensuring the pushrod end hole is clear, and check the pivot area for wear or cracks; replace any damaged components. Inspect the pushrods for cracks and bend by rolling them on a flat surface. Lubricate the lower end of each pushrod and reinstall them, ensuring they seat completely in the lifter. Apply grease to the valve stems and pushrod ends before positioning the rocker arms, then install the pivot balls and nuts, applying grease to prevent damage until oil pressure builds. For valve adjustment, bring the number one piston to top dead center on the compression stroke, tighten the rocker arm nut until all play is removed, then tighten an additional full turn. Adjust the valves for cylinders 1, 5, 6, and intake valves for cylinders 1, 2, and 3, then rotate the crankshaft to TDC for cylinder four and adjust the corresponding valves. Finally, install the rocker arm covers and start the engine, checking for unusual noises and oil leaks. For models from 2000 and later, detach the rocker arm cover(s) and loosen the rocker arm mounting bolts, removing the assemblies and storing them in marked containers. Remove the rocker arm support and pushrods, inspecting all components for wear and damage. Lubricate the pushrods and install them in their original locations, applying assembly oil to the rocker arm roller bearing pivots. Position the rocker arm support correctly and install the rocker arm assemblies, tightening the bolts finger-tight initially. Bring the number one piston to TDC on the compression stroke, tighten the rocker arm bolt until all play is removed, then tighten an additional full turn and to the specified torque. Adjust the valves for cylinders 1, 5, 6, and intake valves for cylinders 1, 2, and 3, then rotate the crankshaft to TDC for cylinder four and adjust the corresponding valves. Finally, install the rocker arm covers, start the engine, and check for unusual noises and oil leaks.
