GM 12645526 Cylinder Head Kit

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Loosen the head bolts in a specific sequence and remove them by hand. Take note of their lengths and positions.

To replace the cylinder heads, begin by disconnecting the negative battery cable and relieving the fuel system pressure. Drain the cooling system and remove the engine/transaxle assembly. Then, proceed to remove the intake manifold(s), valve covers, and upper timing chains. Disconnect the ground wires from the heads, along with various connectors and hoses depending on the head being removed. Loosen the head bolts in a specific sequence and remove them by hand, taking note of their lengths and positions. Carefully lift the heads off the engine block, avoiding prying and placing them on wooden blocks. For installation, ensure clean mating surfaces on both the cylinder heads and block, using gasket removal solvents if needed. Clean surfaces thoroughly to prevent oil-related sealing issues and remove debris from the cylinders. Inspect the mating surfaces for damage and address it as necessary. Chase the threads in the head bolt holes or clean them with brake cleaner to ensure proper torque readings. Position new gaskets over the dowels in the block and carefully place the heads without disturbing the gaskets. Coat the threads of the new 8 mm head bolt(s) with thread locking compound and install them finger-tight, followed by the new 11 mm head bolts, tightening them in a specified sequence to torque specifications and angle of rotation. Complete the installation by following the reverse of the removal process, including reinstalling the engine/transaxle assembly, changing the engine oil and filter, and refilling the cooling system. Finally, start the engine and check for proper operation and any coolant or oil leaks.

Chase the threads in the head bolt holes or clean them with brake cleaner to ensure proper torque readings during installation.