GM 91173879
Camshaft

To remove the Camshaft, disconnect the negative Battery Cable and remove the valve rocker arm cover and the Timing Belt. Next, pull off the Camshaft Timing Belt pulley as well as the Camshaft sensor from its house. Lay a shop rag in the area where the Camshaft housing will be removed to catch any oil that hates. Then take off three Camshaft sensor housing bolts and the Camshaft housing itself from the Cylinder Head. Loosen all valve adjusting screw lock nuts and adjust screws back to permit free motion of the rocker arms. Remove the twelve Camshaft housing bolts gradually in the specified order and get the Camshaft housings and the Camshaft out of the Cylinder Head. For installation pour clean engine oil on the cams, journals, and the oil seal and install the Camshaft into the Cylinder Head. After applying engine oil to the housing bolts, they should then be tightened in a specified sequence to 11 nm (97 inch lbs.). Install the Camshaft oil seal beyond being flush with housing surface and then the Camshaft timing sprocket. Make sure that the pin from the Camshaft goes into the slot formed by the sprocket, and secure it with the Camshaft timing sprocket bolt with 60 nm (43 ft. Lbs.). Change the Timing Belt and adjust the valve lash by positioning the number one cylinder at the top dead center and the Camshaft in the right phase and adjust the valves as 1,2,8 and 6 and turn the Crankshaft for one revolution (360°) to adjust the valve as 3,4,7 and 5. Finally, mount the Camshaft sensor housing to the Cylinder Head using 11 nm (97 ft. Lbs.), the cam sensor to the housing, installation of the valve rocker arm cover and connecting back the negative battery lead.

A replacement will start with disconnecting the battery negative terminal followed by removing the valve rocker arm cover along with the Distributor and Distributor housing. Lift the vehicle to position it properly then take out the Timing Belt. A proper holding device maintains the Camshaft gear stationary during bolt removal before removing the Camshaft timing gear. Before removing any parts from the cylinder head ensure the Crankshaft maintains its correct position. Next remove six bolts and three Camshaft housings (1, 2, 3) from the cylinder head followed by the Camshaft and six hydraulic valve lash (HVL) adjusters. Soak the extracted hvl adjusters in fresh engine oil while they await installation before placing them in contact with any other surfaces. Examine the Camshaft using the outside micrometer (J 26900-20) to check lobe height before replacing the Camshaft when the minimum heights are reached. Engine oil needs to flow through the Camshaft journal holes during installation while hvl adjuster bores should drain oil when installed. Add engine oil around hvl adjusters followed by installation of the adjusters to the cylinder head. Begin by applying engine oil to the Camshaft journal and individual cams. Once complete, place the Camshaft into position with the timing gear pin hole located in the lower position. Apply engine oil along the sliding surface of each Camshaft journal against the housing then distribute gm p/n 12346240 equivalent between the mating surfaces on housing numbers 1 and 3. The installation sequence for the Camshaft housing starts with no. 1 and ends with no. 3 then fasten all housings together using bolts torqued to 11 nm (97 inch lbs.). After applying engine oil to the oil seal lip of the Camshaft users should press-fit the oil seal until it is fully flush with the housing surface. Insert the dowel pin through the Camshaft timing gear pin hole then mount the timing gear with a holding tool to prevent rotation while you tighten the bolt to 60 nm (44 ft. Lbs.). Guard the front cylinder head drain opening by checking that silicone sealant does not block it. Use gm p/n 12346240 or equivalent to seal the corners of the cylinder head gasket before installing the new cylinder head cover gasket and new seal washers and cover nuts tightened to 5 nm (44 inch lbs.). After installing the Distributor case and Distributor remove the Timing Belt and reconnect the negative Battery Cable. A half-hour of no engine operation is needed after installing the hvl adjusters and Camshaft to stop valve and piston collisions. During the engine start the vehicle should reach a slightly higher idle speed to remove air from the hvl adjusters. Check for defects on the hvl adjusters when the noise does not go away.