GM 91177444 Cylinder Head Assembly (On Esn)

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New and rebuilt cylinder heads are usually available for most engines at dealerships and auto parts stores. Because some specialized tools are needed to disassemble and inspect the cylinder head, and because some parts may not be available, It might be more practical and economical to buy a replacement head instead of disassembling, inspecting and reconditioning the old head. For SOHC engines, remove the rocker arms and shafts from the cylinder head. Label the parts or store them separately so they can be reinstalled in their original locations. Remove the distributor case from the cylinder head. On 8 valve engines, gently guide the camshaft out of the cylinder head. Before the valves are removed, arrange to label and store them, along with their related components, so they can be kept separate and reinstalled in the same valve guides they are removed from. Compress the springs on the first valve with a spring compressor and remove the keepers. Carefully release the valve spring compressor and remove the retainer, the spring and the spring seat. Pull the valve out of the head, then remove the oil seal from the guide. Repeat the procedure for the remaining valves. Once the valves and related components have been removed and stored in an organized manner, the head should be thoroughly cleaned and inspected. If a complete engine overhaul is being done, finish the engine disassembly procedures before beginning the cylinder head cleaning and inspection process. For DOHC engines, remove the camshafts and lifters. The remainder of disassembly is similar to the disassembly procedure for SOHC engines except that you'll need a different kind of valve spring compressor. Be very careful not to nick or otherwise damage the lifter bores when compressing the valve springs. There are two valve springs per valve on DOHC engines. Be sure to keep each valve spring pair together. Also, note that each spring has a "top" and "bottom." The largepitch end is the top of the spring; the smallpitch end is the bottom.

Disconnect various electrical harnesses and connectors, including those for the EGR valve, IAC valve, TP sensor, EVAP canister purge valve, oxygen sensor, CMP sensor, ECT sensor, fuel injector wire harness, ignition coil connectors, ground wires, and any wiring harness brackets, clamps, and clips.

The cylinder head bolts should be tightened in several stages following the proper sequence to the specified torque.

Install new seals on each of the valve guides.

To effectively clean a cylinder head and associated components during an engine overhaul, follow these steps:Remove old gasket material and sealant from head gasket, intake manifold, and exhaust manifold surfaces.Clear accumulated scale from coolant passages.Eliminate deposits from holes using a stiff wire brush.Clean threaded holes with an appropriate-sized tap.Use compressed air to remove debris.Clean rocker arm shaft oil holes.Utilize solvent to clean and dry the cylinder head and components.Consider using caustic decarbonizing chemicals with caution.