Chevrolet 12611639 Engine Exhaust Manifold Assembly

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To remove the exhaust manifold, first disconnect the cable from the negative battery terminal, then raise the vehicle and support it securely on jackstands. Apply penetrating oil to the exhaust pipe-to-manifold studs and nuts, and disconnect the electrical connector for the oxygen sensor. Remove the nuts and bolts retaining the exhaust pipe(s) to the manifold(s), followed by the engine covers. Next, remove the ignition coils, spark plug wires, and spark plugs from the side being worked on; if both manifolds are being removed, take out all ignition coils, wires, and plugs. For the right-side manifold, remove the oil dipstick and its tube, while for the left-side manifold, disconnect the steering shaft from the steering gear and set it aside. Remove the mounting bolts to separate the exhaust manifold from the cylinder head, and take off the heat shields afterward. For installation, check the manifold for cracks and ensure the bolt threads are clean and undamaged, making sure the mating surfaces are clean as well. Install the heat shields, bolts, and gaskets onto the manifold, ensuring the retaining tabs hold the assembly together. Apply a small amount of medium strength thread locking compound starting at the fourth thread, avoiding the first three threads. Place the manifold on the cylinder head and install the mounting bolts finger tight, then tighten them from the center to the ends using a torque wrench in two steps. If necessary, bend the exposed end of the exhaust manifold gasket back against the cylinder head. Finally, the remainder of the installation follows the reverse order of removal, and after starting the engine, check for exhaust leaks.

Install the inner heat shields, bolts, and gaskets, ensuring the retaining tabs hold the assembly together during installation.