A special valve spring compressor from most aftermarket specialty tool manufacturers is required for this procedure, as the only alternative involves major disassembly of the engine and surrounding components by removing the timing chains and camshafts. This engine is a non-freewheeling (interference) engine, necessitating that the pistons be down in the cylinder bore before compressing the valve and spring assembly to allow for rocker arm removal. Before starting, ensure the transmission is in Park, the parking brake is applied, or the rear wheels are blocked, and remove the ignition coils and spark plugs. Remove the valve cover(s) and label and store the rocker arms and lash adjusters for reinstallation on the same valves. Rotate the engine clockwise by the crankshaft pulley/vibration damper bolt until the pistons are positioned correctly for rocker arm removal, starting from TDC number 1 on the compression stroke. For the 3.7L V6 engine, remove rocker arms from cylinders No. 2 and 6 with the No. 1 piston at TDC, then rotate the crankshaft another 180 degrees to remove the rocker arm from cylinder No. 1, followed by cylinders No. 3 and 5, and finally cylinder No. 4. For the 4.7L V8 engine, follow a similar process, removing rocker arms from cylinders No. 2 and 8, then No. 3 and 5, followed by No. 4 and 6, and finally No. 1 and 7. Use the valve spring compressor to relieve tension on the rocker arm for removal, and if only a few rocker arms or lash adjusters are being replaced, locate the corresponding cylinder number and rotate the crankshaft accordingly. After removing the rocker arms, pull out the lash adjusters and store them with their corresponding rocker arms. Inspect each rocker arm for wear, cracks, and damage, ensuring the rollers turn freely, and check the lash adjuster contact surfaces for wear or damage, confirming they move freely without excessive play. Installation is the reverse of removal, ensuring lash adjusters are installed first and are at least partially full of oil to minimize plunger travel.
