The following are the steps that should be followed to remove both cylinder heads while the notes given below apply to cases whereby one cylinder head alone will need to be removed. Again for the rear cylinder head the
Timing Chain, camshafts and the rocker arms can only be taken off while the front head can be left in place. On the other hand, if front head has to be removed then the rear timing has to be brought out so as to remove the front chain; this will enable camshaft and the rocker arm of rear to remain in position. First, depresurize the fuel system and remove the negative terminal from the battery next drain the cooling system and remove upper and lower intake manifolds. Suction out the engine oil and see that the oil pan and the engine front cover are removed. Go on and take off the timing chains, camshafts, rocker arms, and lash adjusters inasmuch as needed, exhaust manifold(s), and water pump with its housing. For models from 2009 and further, you have to take away the upper radiator support brackets, and for all versions, you have to do the same with the oil dipstick and its tube. Exhaust the EGA valve pipe and take out the hoses and connectors attached to the coolant bypass tube and also extract the fasteners holding the tube to prevent it from lodging elsewhere. The cylinder head bolts should now be slackened in the reverse order that was used when tightening, they should then be removed and discarded and replaced with new Torque-to-yield bolts. It is recommended that the cylinder head is withdrawn from the engine block with great precaution so as to avoid scratching the mating surfaces of the head and the block; the old gasket should then be thrown away. When you are about to fit in the new cylinder head make sure that the mating surface is clean and also check for signs of damage. If needed, use shop towel and solvent required to clean the surface areas and make sure that locating dowels are installed, and there are no deposits or rather contamination of bolt holes. Place new gaskets over the dowels and using the previous torque settings fit the cylinder heads in their corresponding places and fit new bolts just enough that they do not go fully tight. Torque level is to be set by leveraging a torque wrench along with an angle gauge and the old bolts are to be discarded because it is a type of torque-to-yield bolt. As for the remaining parts return to the sequence by which they were removed tightening the fasteners to the torque specifications, add fresh oil in the engine and coolant in the cooling system. Connect the battery, turn the engine and bay watch for some time for any signs of leaks, and this way giving the Powertrain Control Module an opportunity to relearn its idle and fuel trim for better performance.