Relieve the fuel system pressure, then disconnect the cable from the negative battery terminal. Drain the cooling system and remove the intake manifold(s), followed by the
Exhaust Manifold. Next, remove the valve covers, camshafts, and tappets, and take off the drivebelt and the drivebelt tensioner. Remove the two Camshaft Position (CMP) sensors at the rear of each cylinder head, disconnect any other electrical connectors from the cylinder head, and mark them with tape for correct reassembly. Loosen the cylinder head bolts in 1/4-turn increments until they can be removed by hand, working from bolt-to-bolt in a reverse pattern of the tightening sequence, and discard the bolts as new ones must be used for reinstallation. Lift the cylinder head(s) off the engine, taking care not to pry between the cylinder head and engine block to avoid damage; use a wood block and hammer if resistance is felt, and store the cylinder heads on blocks of wood to protect the gasket sealing surfaces. Disassembly and inspection of the cylinder heads should be conducted by a qualified automotive machine shop, ensuring that the mating surfaces of the cylinder heads and engine block are perfectly clean upon installation. Avoid using scrapers or abrasive discs on aluminum components, and cover all openings with shop rags to prevent debris from entering the engine, using a vacuum cleaner to remove any fallen debris. Check the engine block and cylinder head mating surfaces for nicks, deep scratches, and other damage; slight damage can be addressed with a file, while excessive damage may require machining. Use a tap of the correct size to clean the threads in the block head bolt holes, as dirt, corrosion, sealant, and damaged threads can affect torque readings. Position the new gasket(s) over the dowel pins in the engine block, ensuring proper orientation, and if replacing the cylinder head, a new secondary timing chain tensioner will be necessary. Carefully place the cylinder head(s) on the engine block without disturbing the gasket(s), lightly oil the threads of the new cylinder head bolts before installation, and tighten them finger tight. Follow the recommended sequence to tighten the bolts to the specified torque. The remaining installation steps are the reverse of removal, and after completing the installation, change the engine oil and filter, refill the cooling system, start the engine, and check for oil and coolant leaks.