GM 12596994 Seal,Valve Stem Oil

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Valve springs and valve stem seals can be thereby changed without removing the cylinder head, these two components need two special tools and a compressed air supply. Start with the spark plugs and the valve covers, turn the crankshaft until the #1 piston is on the top in the compression stroke. Take off the rocker arms of the number 1 piston, screw an adapter in the spark plug hole and attach an airline from the source of compressed air. Put compressed air to the cylinder to close the valves and then use the shop rags to block the cylinder head holes around the valves to avoid dropping of the parts and tools in the engine. They should be tapped lightly with the palm of your hand to break the seal and then they require the use of valve spring compressor to compress the spring while the keepers can be removed by using small needle-nose pliers or by use of magnet. Take out the valve spring and retainer using strictly the pressure of air to keep the valve shut in order to prevent damaging it. Take out the old valve stem seals - take note that the intake and exhaust seals differ, secure a rubber band or tape around the top of the valve stem to prevent it from falling into the combustion chamber when you release the air pressure. Although this valve is relatively simple, there are several things you have to look at the valve stem, which should not bind in the guide. Reduce air pressure to hold the valve closed, then install the new valve stem seals up to the specified thickness, without clamping them up against their topped guide. Place the spring and retainer on the valve, press the assembly just enough to fit the keepers into place and drop a small quantity of grease if one is needed to hold the keepers into place. Pull the air hose off and remove the adapter from the spark plug hole and then follow the same procedure for all the rest of the cylinders, always sticking to the firing order and basically going through all of the puffs while bringing each of the pistons to the TDC on the compression stroke. Last, bolt on the rocker arm assemblies and the valve covers and crank the engine, inspecting for mainative oil leakage and other odd noises and should let the engine run for at least five minutes at idle and then bring up to its high end rpms.

Install the new valve stem seals to the specified depth without forcing them against the top of the guide.

Repeat the procedure on the remaining cylinders, following the firing order sequence and bringing each piston to Top Dead Center on the compression stroke.