GM 96065427 Engine Cylinder Head

Allow the engine to cool completely before following this procedure. Position the number one piston at Top Dead Center, then disconnect the negative cable from the battery. Drain the cooling system and remove the spark plugs. Remove the intake manifold, followed by the exhaust manifold. Remove the distributor and unbolt the distributor case from the cylinder head. For carbureted models, remove the fuel pump and pushrod. Next, remove the timing belt and the valve cover. Loosen the cylinder head bolts, 1/4-turn at a time, in the recommended sequence until they can be removed by hand. Carefully detach the cylinder head from the block and place it on wooden blocks to prevent damage to the sealing surfaces. If the head sticks to the engine block, dislodge it by prying against a protrusion on the head casting, avoiding prying between the gasket surfaces. Inspect the camshaft and have the head checked for warpage and cracks, even if just replacing the gasket. The mating surfaces of the cylinder head and block must be perfectly clean when the head is installed; use a gasket scraper to remove all traces of carbon and old gasket material, then clean the surfaces with lacquer thinner or acetone. If there's oil on the mating surfaces when the head is installed, the gasket may not seal correctly and leaks may develop. Stuff the cylinders with clean shop rags to keep out debris and use a vacuum cleaner to remove material that falls into the cylinders. Check the block and head mating surfaces for nicks, deep scratches, and other damage; slight damage can be removed with a file, while excessive damage may require machining. Use a tap of the correct size to chase the threads in the head bolt holes, and mount each bolt in a vise to run a die down the threads to remove corrosion and restore them. Place a new gasket on the block with the side marked TOP facing up, ensuring the openings in the gasket and block are aligned, then set the cylinder head in position. Tighten the cylinder head bolts in three equal steps following the proper sequence until they're all at the torque. Reinstall the timing belt and the remaining parts in the reverse order of removal. Be sure to refill the cooling system and check all fluid levels. Rotate the crankshaft clockwise slowly by hand through two complete revolutions and recheck the camshaft timing marks. Start the engine and set the ignition timing. Run the engine until normal operating temperature is reached, checking for leaks and proper operation. Shut off the engine, remove the valve cover, and retorque the cylinder head bolts unless the gasket manufacturer states otherwise, then recheck the valve adjustment.

The disassembly process involves removing the camshaft, intake and exhaust valves, and related components, with careful labeling or separate storage to ensure proper reinstallation.

Remove all built-up scale from the coolant passages and use a stiff wire brush to clear deposits from various holes.

If the head was serviced, the valves and related components will already be in place.