The crankshaft or the camshafts cannot be rotated at any one time once the timing chain(s) have been removed as this will lead to serious damages to the valves and or the piston; there are special tools used to immobilize the camshafts during the removal of timing chains and it is always advisable to read through the entire procedure and ensure that all the required tools have been acquired. Due to it being an interference engine design, when a chain breaks, valves or pistons will be damaged and the cylinder head will have to be taken off. The timing system is quite intricate and mistakes made are can lead to heavey losses to the engine thus only professionals should attempt this process and all the work done should be cross--checked before starting the engine. It is done by pulling out the negative cable of the battery, setting the number one cylinder to TDC and then, the spark plugs are pulled out. Secondly, the valve covers, as well as the timing chain cover should be detached, and attention should be paid to the fact that there are two lengthy timing chains between the crankshaft and the camshafts. Crankshaft position sensor toothed-wheel must be unclamped and then retrieved gently to avoid damage otherwise when replacing the spur, it must be ensured that it is placed in the correct orientation. Fit in the camshaft and crankshaft retaining tools such that the camshafts cannot move as a result of pressures from the valve springs. When positioning the engine at TDC, lock the keyways on the camshaft sprockets to be at right angles with the valve cover mounting surface. For specific engine types camshaft retaining tools must be fitted and the camshaft(s) must only be retained at exactly TDC as any error can lead to severe engine damage. Rotate the crankshaft groove to 12:00 for 5.4L 3V engines and also there is a valve spring depressor tool been used to take off the rocker arms into their corresponding camshaft lobe positions. The tensioners should be removed and the chains lifted off the camshaft sprockets with the timing marks observed with the intention of being realigned in the correct manner. Remove crankshaft sprockets at both ends, and if necessary, lock crankshaft in position before removal; also both chain guides should be unbolted and removed if required too. Check sprocket teeth, chain and guide for wears and tears and replace them with new ones if they are badly worn. Early-style tensioners should be tested for operation and the presence of the oil feed hole should be ascertained, whereas later-style tensioners should have their seals intact and the plungers should move freely. In installation perform a manual rotation of the crankshaft up to two full turns to evaluate the resistance in the crankshaft which is suggestive of a problem. Place fixed chain guides, crankshaft sprockets and timing chains: the bright faces of the links engaged with the marks on the sprockets. To individual types of engines, it is necessary to complete such procedures as the installation of camshaft sprockets, timing chains, and tensioners with attention to the relative positioning of the timing marks. Last of all, take out any retaining tool, replace rocker arm if any before fully engaging the crankshaft to ensure the right assembly so as to end the process of the installation.
