GM 12638172 Camshaft,Intake

You can Select Your Vehicle to check if 12638172 fits your vehicle.

The camshaft bearing caps are marked with numbers and letters, with a raised arrow indicating the front of the engine. This procedure requires special tools, such as timing chain holding tools (EN 48383-2 and EN 48383-3), to be used; otherwise, you have to remove the timing chain cover in order to properly attach the chain to the lower sprockets. Disconnect battery cable first. Then remove valve covers, power steering fluid reservoir, lower intake manifold for 2008 and earlier models, Camshaft Position (CMP) sensors, camshaft position actuator solenoid valves, and high pressure fuel pump for 2009 and later models if working on left side camshafts. Rotate the engine until flats on camshafts face up. Loosen actuator bolts while holding camshafts with wrench checking end play of the camshaft. Securely install timing chain holding tool (EN 48313) at appropriate points so that it securely holds the timing gears in place then remove camshaft actuator bolts and separate actuators from them. Put these caps into a named box and unscrew their bolts gradually but in reverse sequence following tightening pattern. Inspect all camshafts for wear and measure all bearing journals and lobes. Clean and inspect block's bearings for the cams. Lubricate camshaft properly while positioning it correctly during installation and tightening cap bolts in proper sequence is necessary as well. Do this same thing with other cylinder head cams. Finally, do everything listed above backwards only now changing oil; install new oil filter before starting engine.

The removal of it turns out to be complicated and special tools are needed, new camshaft sprocket bolts, which you should probably buy every time. There are three special implements required to hold the timing chain relative to the cylinder head on the intake and the exhaust side. Then the pressure of the fuel system must be released and the negative terminal of the battery must be disconnected whereas the air filter housing, the ignition coils, the spark plugs, and the valve cover should be unbolted. The timing chain tensioner is then removed, the crankshaft is turned in order to place the special tool that will loosen the camshaft actuator bolts in place. All actuators are tagged for the re assembly and the upper chain guide is also taken off. Other tools are used to secure the timing chain before the removal of camshaft actuators and camshaft solenoids. Camshaft cap is identified by its location and orientation; the camshafts are lifted off the cylinder head but all the related accessories have to remain neat. The hydraulic lash adjusters are located on the heads or issuces of their respective rockers and properly storrage with the rockers. Lash adjusters, for example, are checked for wear or damage, and the measurements of the rocker arms as well as camshaft lobes are gone through to meet a specified gauge. Any elements, which are recognized as worn beyond their acceptable limit, have to be replaced. There is also the lubrication of the rocker arms and the lash adjusters, correct setting of the camshafts and the final tightening of the bearing caps as per a set sequence. Camshaft sprocket actuators and timing chain are put in position and screwed then timing chain tensioner is reprogrammed. Last of all, the upper timing chain guide is bolted and tightened and the battery connection is restored and the process is then done.

The camshaft bearing caps are marked with numbers and letters, with a raised arrow indicating the front of the engine. This procedure requires special tools, such as timing chain holding tools (EN 48383-2 and EN 48383-3), to be used; otherwise, you have to remove the timing chain cover in order to properly attach the chain to the lower sprockets. Disconnect battery cable first. Then remove valve covers, power steering fluid reservoir, lower intake manifold for 2008 and earlier models, Camshaft Position (CMP) sensors, camshaft position actuator solenoid valves, and high pressure fuel pump for 2009 and later models if working on left side camshafts. Rotate the engine until flats on camshafts face up. Loosen actuator bolts while holding camshafts with wrench checking end play of the camshaft. Securely install timing chain holding tool (EN 48313) at appropriate points so that it securely holds the timing gears in place then remove camshaft actuator bolts and separate actuators from them. Put these caps into a named box and unscrew their bolts gradually but in reverse sequence following tightening pattern. Inspect all camshafts for wear and measure all bearing journals and lobes. Clean and inspect block's bearings for the cams. Lubricate camshaft properly while positioning it correctly during installation and tightening cap bolts in proper sequence is necessary as well. Do this same thing with other cylinder head cams. Finally, do everything listed above backwards only now changing oil; install new oil filter before starting engine.

For installation, ensure sealing rings are in place and lubricate the bearing journals and cam lobes with assembly lube.

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.

Always install new lifters as well, as old lifters should not be used with a new camshaft.

Begin by removing the intake manifold or supercharger, valve covers, rocker arms, pushrods, timing chain, timing chain tensioner, cylinder heads, oil pan, oil pump, oil deflector, radiator, air conditioning condenser, and the Camshaft Position sensors.

After removal, clean the camshaft and inspect the bearing journals for wear, pitting, or seizure, replacing both the shaft and bearings if damaged. Measure the bearing journals and camshaft lobes for excessive wear, checking for heat discoloration and other damage.

The removal procedure is complex and requires special tools, including new camshaft sprocket bolts that should be purchased beforehand.

Take out the bolts securing the camshaft thrust plate to the block and remove the thrust plate.

Store the bearing caps in a labeled box, then remove the camshaft bearing cap bolts in reverse order of tightening, and inspect the camshafts for wear and damage using a micrometer.

Store the bearing caps in a labeled box, then remove the camshaft bearing cap bolts in reverse order of tightening, and inspect the camshafts for wear and damage using a micrometer.

Begin by disconnecting the battery cable, removing the valve covers, power steering fluid reservoir, lower intake manifold (for 2008 and earlier models), Camshaft Position (CMP) sensors, camshaft position actuator solenoid valves, and, for 2009 and later models, the high-pressure fuel pump (if working on the left side camshafts).

Check the camshaft bearings in the block for wear and damage, looking for galling or pitting, and inspect the housing journals for any necessary replacements.