GMC 11588728 Bolt, Heavy Hx Acorn Flange Head

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Remove the spark plugs and the valve covers, camshafts and rocker arms. Thread an adapter into the spark plug hole and connect an air hose from a compressed air source to it. Most auto parts stores can supply the air hose adapter. Apply compressed air to the cylinder. The valves should be held in place by the air pressure. Using a socket and a hammer, gently tap on the top of each valve spring retainer several times, then use a valve-spring compressor to compress the spring. Remove the keepers with small needle-nose pliers or a magnet. Remove the valve spring and retainer. Remove the old Valve Stem Oil Seals, noting differences between the intake and exhaust seals. Wrap a rubber band or tape around the top of the valve stem so the valve won't fall into the combustion chamber, then release the air pressure. Inspect the valve stem for damage. Rotate the valve in the guide and check the end for eccentric movement. Move the valve up-and-down in the guide and make sure it does not bind. Reapply air pressure to the cylinder to retain the valve in the closed position, then remove the tape or rubber band from the valve stem. If you're working on an exhaust valve, fit the new exhaust Valve Stem Oil Seal on the valve stem and press it down over the valve guide. If you're working on an intake valve, install a new intake Valve Stem Oil Seal over the valve stem and press it down over the valve guide. Install the spring and retainer in position over the valve. Compress the valve spring assembly only enough to install the keepers in the valve stem. Position the keepers in the valve stem groove. Apply a small dab of grease to the inside of each keeper to hold it in place if necessary. Remove the pressure from the spring tool and make sure the keepers are seated. Disconnect the air hose and remove the adapter from the spark plug hole. Repeat the above procedure on the remaining cylinders. Install the rocker arm assemblies, camshafts, timing chains and the valve covers. Start the engine, then check for oil leaks and unusual sounds coming from the valve cover area. Allow the engine to idle for at least five minutes before revving the engine.

Finally, reinstall the rocker arms, support bars, and pushrods, followed by the valve cover(s), spark plug(s), and wires.

To remove the spark plugs, valve covers, and rocker arms, start by rotating the crankshaft until the number one piston is at Top Dead Center on the compression stroke. Then, thread an adapter into the spark plug hole and connect an air hose from a compressed air source to it. Apply compressed air to the cylinder to hold the valves in place. Stuff shop rags into the cylinder head holes around the valves to prevent any parts or tools from falling into the engine. Gently tap on the top of each valve spring retainer with a socket and hammer to break the seal between the valve keeper and the spring retainer. Use a valve-spring compressor to compress the spring and remove the keepers with small needle-nose pliers or a magnet. Remove the valve spring and retainer, as well as the old valve stem seals. Inspect the valve stem for damage and check for any eccentric movement or binding. If necessary, remove the head for repair. To install new valve stem seals, press them down over the valve guide to the specified depth. Install the spring and retainer, compress the valve spring assembly, and position the keepers in the valve stem groove. Apply a small dab of grease to hold the keepers in place if needed. Repeat this process for the remaining cylinders, following the firing order sequence. Finally, reinstall the rocker arm assemblies and valve covers, start the engine, and check for any oil leaks or unusual sounds. Allow the engine to idle for at least five minutes before revving.

For Valve Stem Oil Seal replacement, first remove the valve cover(s) from the cylinder head(s), and if replacing all seals, remove all spark plugs as well. Identify the cylinder with the defective component or start with cylinder number 1 when replacing all seals, following the firing order sequence (1-6-5-4-3-2) with each cylinder 120 degrees clockwise apart. Rotate the crankshaft to position the piston in the chosen cylinder at Top Dead Center on the compression stroke. Remove all rocker arms, pushrods, and support bars from the targeted cylinder head. Thread an adapter into the spark plug hole and connect it to a compressed air source, applying 90 to 100 psi of pressure to secure the valves in place. Prevent foreign objects from entering the engine by placing shop rags in the cylinder head holes. Utilize a valve spring compressor to compress the valve spring and retainer, allowing the removal of the keepers. Take out the spring retainer or rotator, as well as the valve spring assembly, and extract the old Valve Stem Oil Seal from the valve guide. To avoid valve dropping, secure the valve stem with a rubber band or tape, then release the air pressure. For installation, inspect the valve stem for damage and ensure it moves freely without binding in the guide. Reapply air pressure to keep the valve closed, then remove the tape or rubber band. Lubricate the valve stems with engine oil and install the new Valve Stem Oil Seals, tapping them gently into place using a seal installation tool or deep socket, taking care not to twist or cock the seals. Confirm the garter spring is properly positioned around the top of each seal. Proceed to install the valve spring and damper if equipped, with the closely-wound spring coils facing the cylinder head, and secure the valve spring retainer or rotator. 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.