GM 12604896 Camshaft Assembly, Exhaust

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Before undertaking the tedious process of removing and inspecting camshafts, you should gather your special tools and get some new bolts for camshaft sprockets. On a 2.0L supercharged model, start by releasing the fuel system pressure; then disconnect the negative battery terminal. Remove the valve cover and set the engine to TDC for cylinder number one, then rotate the crankshaft anti-clockwise until the engine is at 60 degrees before TDC with a diamond-shaped hole on an intake camshaft at 12 o'clock. One thing to remember is never remove camshafts with the engine at TDC number 1 or else valves will collide with pistons and cause damage to both parts. For these engines (2.0L Supercharged & 2.2L), remove upper timing chain guide & secure camshaft sprockets by special tool. To facilitate this process, buy a camshaft locking tool.Remove and put wingnuts on side holding forwardly moved tape-worm wheels.Possibly remove the Camshaft Position Actuators if working on vehicles built during or after 2009; otherwise remove Timing Chain Tensioner if working on vehicles built before 2008.Then disassemble cams while keeping caps marked as to location and direction in which they were removed.All rocker arms must be returned to their original position while all hydraulic lash adjusters should be placed along with corresponding rocker arms.The same procedure should also be used to lift up hydraulic lash adjusters after removing rocker arms from exhaust camshafts in order.Specially made tools hold chain tight & release actuator after loosening actuator bolts while holding wrench onto hexagon of camshaft.Ensure that timing chain remains propped up by locking devices.If removing cams check all engines for proper lubrication between hydraulic lash adjusters, rocker bearings lobes of cams, bearing journals and bearing journal oil clearance.Correct any deficiencies encountered by replacing the parts which are faulty.Prior to reinstallation of rocker arms, ensure they are well oiled together with hydraulic lash adjusters, camshaft must be lubricated and installed correctly.Slide the camshaft sprockets down, tighten new bolts to the required torque and align the slots with sprocket projections before securing the camshaft bearing caps.Adjust the bolts on parts that have been mispositioned during installation.Make sure that you remove Camshaft Locking Tool then install front and rear Camshaft Caps as guided by manufacturers' specifications.Replace upper timing chain guide and also install timing chain tensioner back.Reset&install tensioner & fit upper timing chain guide for it.Once it has gone through at least two complete revolutions check for any kind of resistance involved in making those revolutions.Go ahead to reconnect your battery in order to proceed with engine operation.

For these engines, remove the upper timing chain guide and use a special tool to secure the camshaft sprockets in place. 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.