GM 12623064 Camshaft Asm

Disconnect the cable from the negative battery terminal, then rotate the engine until the #1 cylinder is at Top Dead Center (TDC) on the compression stroke. Remove the valve cover(s) and the timing belt. Rotate the crankshaft 60 degrees counterclockwise to prevent the valves from possibly hitting the pistons, then remove the camshaft sprocket bolts and sprockets. Each camshaft bearing cap has a double-digit identifying number etched on it, with specific numbering for the exhaust and intake camshaft bearing caps on both sides of the engine. Loosen the camshaft bearing cap bolts progressively by half a turn at a time to gradually release the pressure of the valve springs. Withdraw the caps, noting their markings and the presence of locating dowels, then remove the camshafts and front oil seals, identifying the intake and exhaust camshafts by their respective stamps. Use twelve small, clean containers to store each Lash Adjuster, ensuring they are not interchanged. With the camshafts and Lash Adjusters removed, check for signs of wear and measure the outside diameter of each Lash Adjuster at multiple points. Visually examine the camshaft lobes and bearing journals for wear or pitting, and measure the diameter of each journal. To check the bearing journal running clearance, clean all bearing surfaces, install the camshafts and bearing caps with Plastigage across each journal, then measure the width of the compressed strands. If any bearing is worn beyond specified limits, install a new camshaft and repeat the check. For camshaft endplay, clean the bearing surfaces, install the camshafts and bearing caps, then measure the endplay using a dial indicator. If the endplay exceeds specified limits, install a new camshaft. Confirm the crankshaft is positioned at 60 degrees BTDC, then oil the cylinder head Lash Adjuster bores and install the Lash Adjusters in their original positions. Oil the camshaft bearing surfaces and install the camshafts in their original locations, ensuring the pins are positioned correctly. Apply silicone sealer to the forward edge of the front bearing caps and check that all mating surfaces are clean. Oil the camshaft journals and lobes, then install each camshaft bearing cap, ensuring the numbered side faces outwards. Tighten the camshaft bearing cap bolts in sequence until each cap touches the cylinder head, then to the specified torque. Coat the lip of the camshaft seal with clean engine oil, press it into the end of the bearing cap, and use a seal driver to ensure it is flush and square. Finally, install the camshaft sprockets to the correct camshafts, ensuring the camshaft pin is in the same numbered slot on the sprocket it was removed from, and tighten the new camshaft sprocket bolt to the specified torque.

The camshaft bearing caps are numbered consecutively starting with the front of the engine; lettered either 'I' for intake or 'E' for exhaust; and bear an indentation pointing forward. For this procedure, special timing chain holding tools EN 48383-2 and EN 48383-3 are required; otherwise the timing chain cover has to be disconnected to keep the chains on the lower sprockets. First of all, you shall have to remove the negative cable of the battery, the valve cover or covers, the power steering fluid register, the lower intake, the CMP sensor and the camshaft position actuator solenoids. If for some reason it is necessary to remove the left-side camshafts, then it is necessary to pull out the high-pressure fuel pump. Tilt the engine in way that the camshaft flats are on the top, and in line with the plane of the cylinder head, then measure the endplay with the help of the dial gauge. Using an open-end wrench, hold the camshafts and use a socket wrench to remove the camshaft position actuator bolts. In place the special tool that clamps the timing chain and sprockets and mark match points on the actuators and the chain. Take out the bolts for the camshaft actuator and the actuators themselves, and put the bearing caps in a box named for later replacement. Camshaft bearing cap bolts 022 082: slacken and remove in reverse order to the torque sequence 134 Nm, and check the camshafts for wear or damage by measuring the journal diameters and the lobe heights. It is advised to remove the camshaft for cleaning and afterwards check the bearing journals for any sign of wear, pitting or seizure of the camshaft Journal and the bearing while the shaft and bearings are replaceable if damaged. Bearing journals and camshaft lobes; the wear should be gauged with Micrometrical measurements tools and appear as dark and glossy due to heat. The inside diameter of each bearing should be measured in order to check the oil clearance and if found to be very high, new bearings are required. In camshaft bearing replacement, precision and specialty tools coupled with technical know how is needed and hence, the block should be taken to an automotive machine shop. Some of the checks to be made are that sealing rings are fitted, and camshaft bearing journals together with lobes need to be lubricated. Position the camshafts back to the bearing journals low tension area before applying engine oil on the bearing caps before finally reinstalling them back in their respective positions while their arrow face the center of the cylinder head. Torque the bearing cap bolts to 200 lb-in in the sequence mentioned above and do the same thing for the left side cylinder head camshafts. The rest of the procedure is the reverse of the above order and, before engaging the engine, the oil should be changed and a new oil filter fitted.

Complete the installation by reversing the removal steps, and before starting the engine, change the oil and install a new oil filter.

Store bearing caps and lifters in a labeled box for proper reinstallation.

Before removing the lifters, store them in a clearly labeled box to ensure they are installed in their original locations.