These are hard to service and some special tools are necessary. Any process that involves
Timing Chain,
Timing Belt should be handled with care because any mishandling would result in the engine being damaged. Timing is an intricate system and any error can be extremely harmful hence only very experienced people should take up such procedures and it is recommended that an expert be consulted in case there is any doubt. Check the valve clearances before the removal of the camshafts, and then remove the
Intake Manifold. In turbocharged models, de-pressurize the fuel system, and take out the high-pressure fuel pump and drive housing, then the brake vacuum pump. Then take off the timing belt or chain followed by the camshaft sprockets or the VCT units and label them to be fitted back. On certain models, loosen the variable camshaft timing solenoid fasteners and loosen the camshaft seals that you find on models. Unscrew the bolts on the front camshaft bearing cap and take it out and after installation, replace the O-ring. Apply heat on the sealant of some engines with the heat gun to prevent damage. Record the identification numbers of the bearing cap of camshafts and slack the bolts gradually to discharge pressure evenly. Take off the caps, and make a note of the labelings on the caps, then take off the camshafts and seals of the oil. Labelling of the valve shims to be installed should be carried out by placing them in labeled containers. Check the valve shims and camshafts in terms of wear as well as the diameters of the cam followers, and look at any evidence of damage. Where required, change worn out parts. Test the valve clearance and observe the condition of the lobes of the camshaft and bearing surfaces. Measuring the diameter of each journal and cross-checking the running clearance using Plastigage. In case one of the bearings has been damaged to an extent that it can no longer bear, change the camshaft and inspect the cylinder head. Checking camshaft endplay To measure camshaft endplay, use a dial indicator. Excessive one may replace the camshaft and even the cylinder head. Installation, adjusting check valves in case of installing new ones, rotation of the crankshaft to a certain position, attaching the cam followers and camshafts. Install bearing caps sequentially and clearance of the valves. Replaced with new camshaft oil seals, with the right way of the camshaft bearing caps to be turned on. Install the bolts to recommended torque levels, wipe up excess sealant and leave to cure. Once valve clearances have been checked, put the sprockets and phasers in place, screwing the bolts loosely. Proceed with reassembly of timing belt or chain, and valve clearance before placing valve cover. Lastly, re-connect the battery and leave the Powertrain Control Module to re-learn its idle and fuel trim strategy to achieve optimum performance.