GM 90537255 Camshaft Asm,Exhaust

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To remove the camshafts, begin by disconnecting the cable from the negative battery terminal and setting the engine to 60-degrees before TDC. Take off the valve cover(s) and timing belt. Use a wrench on the hex drive of the camshaft to prevent it from turning while removing camshaft sprockets, making sure to mark their original positions. Pick off bearing caps from the cylinder head and take note of their original locations. Remove camshafts from cylinder head along with camshaft seals. Put each lash adjuster in numbered containers to prevent mixing them up. This process has to be repeated for rear cylinder head only camshafts. Check if there is wear and roundness on all cams and lash adjusters after removing them. Compare measurements after measuring outside diameter for each lash adjuster. Inspect wear or overheating on lobe of every camshaft. Check measurements after measuring lobe height for each cam lobe. Inspect these parts for wear or pitting: - Camshaft bearing journals - Cylinder head bearing surfaces Measure each journal's diameter, checking for excessive wear too;… For this purpose, clean the bearing surfaces and install the Plastigage-carrying camshafts as well as bearing caps;… To be sure about journal oil clearance, measure compressed strand-width;… To tap towards and away from gauge let it measure endplay of a dial indicator checking in readings;…. After inspection is done, position engine at 60-degrees before TDC again (engine should be rotated by hand). Lubricate cylinder head roller bores (with oil) as well as roller followers and leave them in their original bores once you're done with that operation (again). Put new oil seals on both ends of both cams.… Apply anaerobic sealant between front caps' cylinder head; first caps must have anaerobic sealant applied between them.… Use lubrication for camshaft installation on both the journals and lobes.… Then, attach the camshaft bearing caps in their original positions, ensuring they are tightened down in the proper sequence. Finally, replace all remaining parts including timing belt and sprocket which will complete reassembly. Finally, connect the battery.

This is a hard process that requires special tools. Take the cable out of the negative terminal of the battery. Get rid of the valve cover. Bring engine to TDC for cylinder number one then turn the crankshaft anti-clockwise until it becomes 60 degrees before TDC. Take off the upper timing chain guide. Place a special tool that will hold camshaft sprockets in place. Remove camshaft sprocket bolts and move camshaft sprockets forward. Remove intake camshaft by loosening each bearing cap nut and lifting off camshaft parallel to surface of cylinder head. Remove rocker arms and hydraulic lash adjusters from the intake camshaft. Mark exhaust bearing caps and remove them from cylinder head-take off rocker arms and hydraulic lash adjusters from exhaust camshaft also. Examine hydraulic lash adjusters for wear, as well as measure their outside diameter-also Do not forget to inspect the rocker arms for wear or damage too. Look at the lobes of the camshafts for any sign of wear, scoring, pitting, galling, or heating up-measure each lobe height on each cam lobe and compare measurements for excessive variation too. Check wear or damage to these surfaces on which these journals are running between these bearing surfaces on cylinder heads-Take care of this Plastigage-bearing journal oil clearance measurement even though it's time-consuming so that you don't mess up anything while doing it, right? Determine if there is any movement between your fingers and this end play should be less than 0.2mm (0.008in). Lubricate all these components prior to re-installing them back into their respective positions including lubricating rockers and hydraulic lash adjusters-to reinstall back in proper places, lubricate cams first . Fit fastenings together with appropriate bolt torque specific for cam bore caps so that they won't fall out anymore after some time. Place the camshaft sprockets along with timing chain on guide pins and then tighten the camshaft sprockets. Place front and rear camshaft caps in their respective positions and tighten them up to specified torque requirements. Fit upper timing chain guide-remember to turn the engine by hand just to check if there is any resistance too. Complete remaining installation procedures as well as reconnecting battery too.

Install the camshaft bearing caps and tighten the bolts to the specified torque. Slide the camshaft sprockets and timing chain along the guide pins and tighten the camshaft sprockets.

Inspect them for wear and roundness.