GM 90537677 Engine Exhaust Manifold Assembly

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Disconnect the cable from the negative battery terminal. Raise the vehicle and support it securely on jackstands. Remove the splash shield from below the engine compartment. Working under the vehicle, apply penetrating oil to the exhaust pipe-to-manifold studs and nuts. Drain the coolant. Remove the oxygen sensor from the exhaust manifold. Install an engine support fixture and remove the transaxle mount through-bolt. Raise the engine slightly to access the coolant extension housing. Remove the oil dipstick and dipstick tube. Remove the coolant extension housing. Remove the power steering pipe bracket. Remove the front exhaust pipe assembly. Remove the oil filter housing assembly. Remove the mounting nuts from the exhaust manifold, then detach the manifold from the cylinder head. Disconnect the EGR pipe from the exhaust manifold. Remove the oxygen sensor from the exhaust manifold. Remove the rear exhaust pipe assembly from the vehicle. Remove the mounting nuts from the exhaust manifold, then detach the manifold from the cylinder head. Check the exhaust manifolds for cracks. Make sure the bolt threads are clean and undamaged. The exhaust manifold and cylinder head mating surfaces must be clean before the exhaust manifolds are reinstalled- use a gasket scraper to remove all carbon deposits. Position a new gasket in place and slip the exhaust manifold over the studs on the cylinder head. Install the mounting nuts. When tightening the mounting nuts, work from the center outwards, alternating between top and bottom rows. Tighten the bolts to the specific torque. The remaining installation steps are the reverse of removal. When reconnecting the EGR tube to the exhaust manifold, use a slight amount of anti-seize compound on the threads. If the front exhaust manifold was removed, refill the cooling system. Reconnect the battery. Start the engine and check for leaks.

Disconnect the cable from the negative battery terminal. If equipped, remove the AIR valve bracket nut, then remove the bolts and disconnect the AIR pipe from the exhaust manifold. Note: It isn't necessary to detach the hose from the AIR valve. Remove the exhaust manifold heat shield. Raise the vehicle and support it on jackstands. Detach the exhaust pipe from the manifold. Follow the lead from the oxygen sensor up to its electrical connector, then unplug the connector. Also detach the lead from its retaining clip. Remove the exhaust manifold mounting nuts and detach the manifold from the cylinder head. Using a scraper, thoroughly clean the mating surfaces on the cylinder head, manifold and exhaust pipe. Remove the residue with a solvent such as acetone or lacquer thinner. Check that the mating surfaces are perfectly flat and not damaged in any way. A warped or damaged manifold may require machining or, if severe enough, replacement. Install the new gasket to the cylinder head studs and place the manifold on the cylinder head. Tighten the nuts evenly, working from the center outwards, to the specific torque. Connect the exhaust pipe to the manifold and tighten the nuts evenly to the specific torque. The remainder of installation is the reverse of the removal steps.

Remove the oil dipstick and dipstick tube, the coolant extension housing, power steering pipe bracket, front exhaust pipe assembly, and the oil filter housing assembly.

Disconnect the cable from the negative battery terminal.