Buick 12629058 Head Assembly, Cyl (W/ Valve)

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To remove cylinder heads, start by disconnecting the battery cable and draining the cooling system, ensuring fuel system pressure is relieved. Remove the intake manifold, coolant pipe, exhaust manifold(s), valve cover(s), rocker arms, pushrods, and coolant air bleed pipe. For the left cylinder head, remove the alternator and its bracket, and disconnect the ground strap at the back of the cylinder head. For the right cylinder head, remove the dipstick tube and disconnect ground cables from the front of the cylinder head. Loosen the head bolts incrementally in reverse order of the tightening sequence until they can be removed by hand. Lift the head(s) from the engine, using care to prevent damage to mating surfaces. Store the heads on blocks of wood. For installation, ensure the cylinder heads and block mating surfaces are clean and free of debris. Use a gasket scraper and brake system cleaner to clean surfaces, and check for any damage that may require machining. Chase thread holes in the block with a tap or brake cleaner and compressed air, then replace all head bolts with new ones. Position new gaskets on the dowels in the block, place the heads on the block without disturbing the gaskets, and tighten the head bolts to specified torque in the recommended sequence. Install the coolant pipe with new gaskets, then proceed with the reverse of the removal steps. Add coolant, change the oil and filter, start the engine, and check for proper operation and leaks.

To remove the right cylinder head, start by draining the cooling system and removing the intake manifold, valve covers, pushrods, and exhaust manifold(s). Then, remove the alternator bracket and its mounting stud, followed by the spark plugs and spark plug wire support brackets. Loosen the cylinder head bolts in a specific pattern and lift the cylinder head(s) off the engine using a block of wood and a hammer. Store the cylinder heads on wood blocks to prevent damage. For the left cylinder head removal, follow a similar process, but also remove the electrical junction block bracket, power steering pump bracket, ground wire, coolant temperature sensor, and additional spark plug wire support brackets. When installing the cylinder heads, ensure the mating surfaces are clean and free of debris. Check for any damage and use a tap to chase the threads in the bolt holes. Position new gaskets over the dowel pins and carefully place the cylinder heads on the block. Coat the threads of new cylinder head bolts with a non-hardening sealant and tighten them according to the recommended sequence, torque, and angle of rotation specifications. Finally, change the engine oil and filter, and check for any leaks after starting the engine.