GM 12587985 Camshaft,Intake (Machining)

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To undertake the challenging procedure of camshaft removal and inspection, prepare the necessary special tools and acquire new camshaft sprocket bolts beforehand. Begin by relieving the fuel system pressure on 2.0L supercharged models and disconnecting the negative battery terminal. Remove the valve cover and set the engine to TDC for cylinder number one, followed by rotating the crankshaft counterclockwise to position the engine at 60-degrees before TDC with the diamond-shaped hole on the intake camshaft at 12 o'clock. Proceed cautiously, ensuring not to remove the camshafts with the engine at TDC number 1 to prevent damage to the valves and pistons. For 2.0L supercharged and 2.2L engines, remove the upper timing chain guide and use a special tool to secure the camshaft sprockets in place. Purchase a camshaft locking tool to accomplish this task. Remove the camshaft sprocket bolts and slide the camshaft sprockets forward, securing them with wingnuts. If working on 2009 and later models, remove the camshaft position actuators; for 2008 and earlier models, remove the timing chain tensioner. Next, disassemble the camshafts, keeping camshaft caps marked for location and direction, and remove the rocker arms and hydraulic lash adjusters. Organize the rocker arms for reinstallation in their original positions and store the lash adjusters with their corresponding rocker arms. Repeat a similar process for the exhaust camshaft, marking the positions of rocker arms, removing them, and lifting the hydraulic lash adjusters. For 2.0L turbocharged and 2.4L engines, special tools secure the chain and camshaft actuators, allowing their removal after loosening the actuator bolts while holding the camshaft with a wrench on the camshaft hex. Ensure the timing chain is supported by the locking tools. If removing camshafts, carefully inspection on all engines, checking hydraulic lash adjusters, rocker arms, camshaft lobes, bearing journals, and bearing journal oil clearance. Replace components as needed. Lubricate the rocker arms and hydraulic lash adjusters before reinstalling them, then lubricate and install the camshafts with proper alignment. Secure the camshaft bearing caps, slide the camshaft sprockets and timing chain, align the slots with sprocket projections, and tighten the camshaft sprockets with new bolts to the specified torque. For 2.0L, 2.4L, and 2009 and later 2.2L engines, reinstall the camshaft actuators aligned with the marked positions and secure them with new bolts, tightening while holding each camshaft. Remove the camshaft locking tool and install the front and rear camshaft caps, torquing them to specifications. Install the upper timing chain guide and reset and install the timing chain tensioner. Perform two manual engine revolutions, checking for resistance. Complete the remaining installation steps, reconnect the battery, and proceed with engine operation.