GM 91177443 Cylinder Head Assembly (On Esn)

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Disconnect various hoses, including the brake booster hose, vacuum hoses, canister purge hoses, coolant hose, fuel supply hose, return hose, heater hose, and radiator inlet hose.

To effectively evaluate the condition of cylinder head(s) and associated valve train components during an engine overhaul, meticulous cleaning and thorough inspection are essential. Begin by assessing potential cylinder head warping, especially if the engine experienced severe overheating. Cleaning steps involve scrupulously removing old gasket material and sealant from head gasket, intake manifold, and exhaust manifold surfaces, ensuring no damage to the cylinder head. Utilize specialized gasket removal solvents if necessary and clear accumulated scale from coolant passages. Employ a stiff wire brush to eliminate deposits from holes and clean threaded holes with an appropriate-sized tap while using compressed air to remove debris. Clean rocker arm shaft oil holes and use solvent to clean and dry the cylinder head and components, expediting the process with compressed air. Consider using caustic decarbonizing chemicals with caution. For inspection, check the cylinder head for cracks, coolant leakage, and damage, seeking guidance from an automotive machine shop if cracks are present. Evaluate the head gasket mating surface for warpage using a straightedge and feeler gauge, ensuring compliance with specified limits. Inspect valve seats in the combustion chambers for pitting, cracks, or burning. Measure valve stem-to-guide clearance with a dial indicator, involving a machine shop check if needed. Examine valve faces for wear, deformation, cracks, and other issues, ensuring valve stem, neck, and overall condition meet standards. Measure valve margin width and replace valves with narrower margins. Scrutinize valve springs for wear, pits, and sagging, measuring free length and confirming tension with a machine shop check. Assess spring retainers, keepers, and rocker arm components for wear, cracks, and damage, replacing questionable parts. In the case of SOHC engines, review rocker arm faces, pivot contact areas, shafts, and adjusters for damage, wear, and squareness. If components are in poor condition or excessively worn, reassemble valves in the cylinder head. Inspect camshaft journals, rocker arms, and lobes for damage, wear, and overheating evidence. Measure cam lobe height, journal diameter, and housing bore to assess wear and roundness. In DOHC engines, inspect lifter contact and sliding surfaces for wear, damage, and scratches, ensuring lifter movement in its bore. Measure lifter and lifter bore diameters to determine clearance and replace components or cylinder head as necessary.

Do not shim the springs to the point where the installed height is less than specified.

New and rebuilt cylinder heads are usually available at dealerships and auto parts stores.

The first step is to allow the engine to cool completely.