GMC 12565763 Spring, Valve

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To replace the Valve Stem Oil Seals, start by removing the valve cover(s) from the cylinder head(s), and if replacing all seals, remove all spark plugs too. If replacing all seals, go according to firing order (1-6-5-4-3-2) and begin with cylinder number 1 i.e. skip 120 degrees clockwise for each cylinder. Position the piston in that selected cylinder at Top Dead Center on the compression stroke by rotating the crankshaft. For that target cylinder head, remove all rocker arms, pushrods, and support bars. Screw an adapter into the spark plug hole and attach a compressed air source which applies approximately 90 to 100 psi of pressure to retain valves position. Shop rags should be inserted into the holes on top of the cylinder heads to prevent foreign objects from entering into the engine. A removal tool such as a valve spring compressor can help compress retainers together with valve springs thus allowing keepers' elimination. Old Valve Stem Oil Seal is then taken out after getting rid of spring retainer or rotator together with its assembly. Keep the rubber band or tape on hand for holding down the valve stem so that it does not fall out when releasing air pressure later on. While installing, ensure there is no damage on valve stem but it moves freely in guide without sticking inside it. Air pressure should be reapplied to hold down the valve while taking off tape or rubber bands. After applying some engine oil for lubrication purposes around the stem ends of valves install new seals after tapping them gently with a deep socket or tool used for installation of a seal into place, care being taken not to twist or cock these seals in any way at this point also check if garter spring is properly positioned around the top of each seal before proceeding further with the installation process of valve spring and damper if applicable closely-wound spring coils facing towards cylinder head while securing either rotator or retainer for valve spring. Disconnect the air hose, remove the adapter from the spark plug hole, and repeat the process for the remaining cylinders, aligning each piston with TDC on the compression stroke. Finally, reinstall the rocker arms, support bars, and pushrods, followed by the valve cover(s), spark plug(s), and wires, and start and run the engine, checking for any oil leaks or unusual noises from the valve cover area.

Start and run the engine, checking for any oil leaks or unusual noises from the valve cover area.

A valve-spring compressor should be used.

Install the spring and retainer, compress the valve spring assembly, and position the keepers in the valve stem groove.