GM 90537261 Camshaft Asm,Intake

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This is a difficult procedure that requires special tools. Disconnect the cable from the negative battery terminal. Remove the valve cover. Set the engine to TDC for cylinder number one, then turn the crankshaft counterclockwise until the engine is set at 60-degrees before TDC. Remove the upper timing chain guide. Install a special tool to secure the camshaft sprockets in position. Remove the camshaft sprocket bolts and slide the camshaft sprockets forward. Remove the intake camshaft by loosening each bearing cap nut and lifting the camshaft parallel to the surface of the cylinder head. Remove the rocker arms and hydraulic lash adjusters from the intake camshaft. Mark the exhaust bearing caps and remove them from the cylinder head. Remove the rocker arms and hydraulic lash adjusters from the exhaust camshaft. Inspect the hydraulic lash adjusters for wear and measure their outside diameter. Inspect the rocker arms for wear or damage. Examine the camshaft lobes for wear, scoring, pitting, galling, and evidence of overheating. Measure the lobe height of each cam lobe and compare the measurements for excessive variation. Inspect the camshaft bearing journals and cylinder head bearing surfaces for wear or damage. Check the bearing journal oil clearance using Plastigage. Measure the camshaft endplay using a dial indicator. Lubricate the rocker arms and hydraulic lash adjusters and install them in their original positions. Lubricate the camshafts and install them in their correct locations. 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. Install the front and rear camshaft caps and tighten them to the specified torque. Install the upper timing chain guide. Rotate the engine by hand to check for any resistance. Complete the remaining installation steps and reconnect the battery.

Remove the valve cover(s) and the timing belt.

The first step is to disconnect the cable from the negative battery terminal.

To remove the camshafts, start by disconnecting the cable from the negative battery terminal and setting the engine to 60-degrees before TDC. Remove the valve cover(s) and timing belt. Use a wrench on the hex drive on the camshaft to prevent it from turning, and remove the camshaft sprockets, making sure to mark their original positions. Remove the bearing caps from the cylinder head, making note of their original locations. Lift the camshafts from the cylinder head, along with the camshaft seals. Place each lash adjuster in numbered containers to prevent mixing them up. Repeat this process for the rear cylinder head camshafts. Once the camshafts and lash adjusters are removed, inspect them for wear and roundness. Measure the outside diameter of each lash adjuster and compare the measurements. Check the camshaft lobes for wear and overheating. Measure the lobe height of each cam lobe and compare the measurements. Examine the camshaft bearing journals and cylinder head bearing surfaces for wear or pitting. Measure the diameter of each journal and check for excessive wear. To check the bearing journal running clearance, clean the bearing surfaces and install the camshafts and bearing caps with Plastigage. Measure the width of the compressed strands to determine the journal oil clearance. Check the camshaft endplay using a dial indicator. Tap the camshaft towards and away from the gauge and note the readings. Once the inspection is complete, position the engine at 60-degrees before TDC. Oil the cylinder head lash adjuster bores and lash adjusters, and install the lash adjusters in their original bores. Install new camshaft oil seals. Oil the camshaft bearings and lobes. Install the camshafts, ensuring they are in their original locations and aligning the pins correctly. Apply anaerobic sealant between the camshaft cap and cylinder head on the front caps. Apply camshaft installation lube to the journals and lobes. Install the camshaft bearing caps in their original positions and tighten them down in the proper sequence. Install the camshaft sprockets and complete the reassembly process, including replacing the timing belt and setting the valve timing. Finally, reconnect the battery.