Camshafts should always be checked very well before being fitted while endplay of the camshaft should be checked before the removal of the same. Start with the procedure of removing the cable of negative terminal of the battery and engine setting at TDC for No: 1 cylinder. If it is GDI models, first, you have to deal with the engine remove the high pressure fuel pump next, after that, you will have to take off the valve cover. With the TDC marks aligned, put the large wrench on the camshaft and then remove the bolts of the camshaft phaser sprocket but do not take them off completely. Take out the bolt of the service hole in the timing chain cover and it is imperative for one to clean any Loc-tight sealer that may have stuck to the threads if any. For MPI models, there is a special tool to engage with the timing chain tensioner and unlock it, for GDI models the tensioner ratchet should be unlocked using a screwdriver. Remove the front bearing cap, and raise the chain off the sprocket and onto the camshafts; then, unscrew the bolts of the front bearing cap and the upper bearing. Undo the remaining camshaft cap bolts gradually beginning from the outer ones and take off the camshafts from the cylinder head and retain the caps for re-fittingting. Take out the lifters; also ensure that these are in order too. If it is necessary, take off the camshaft phaser sprocket and check all the elements for signs of wear. Previous to the removing of the camshafts, fit the camshaft with a dial indicator to check the end play and observe the condition of the bearing witnesses also. Check the OD of each camshaft bearing journal and the ID of the matching bearings to determine the oil clearance and replace any of them that are beyond the established standards. Take height of the camshaft lobe and also measure the run out on the lobes by using a dial indicator. Scuff each of the lifters in turn. Coating these with the fresh engine oil before reinstalling them in their intended positions ought to be the area where the exhaust camshaft lower bearing will be fitted and the camshaft phaser sprockets. Put on some lubricant for the camshaft lobes and the journals, the camshaft has to be installed with the T.D.C marks in firm sight of each other old camshaft has to go back to where it was. Then put in the upper bearing and the bearing caps and use the right torque to tighten it with a sequence. Position the timing chain over the camshaft sprockets so that it lines up with the phaser sprocket, and fasten the phaser sprocket bolts. For MPI models take out the special tool and check the timing marks; for GDI models take off the tensioner link. Place and fasten a new service hole bolt. For adjustment, you should have the valve cover off and the number one cylinder at TDC on the compression stroke and then using a feeler gauge, check the clearance between the camshaft lobes and the lifters. Turn the engine again and do the same for the other valves; replace the lifters with improper clearances with new ones. Check the thickness of the lifter head then find the right thickness for the replacement. If new lifters and camshafts have been installed, verify clearances, apply installation lubricant to each lash adjuster and replace the lash adjusters to the position they were previously in. Position each camshaft back to their original position and align the timing marks and then install each bearing caps in a sequential manner and then tightening the bolts to the wished torque.
