GM 12552325 Engine Exhaust Manifold Assembly

To gain better access to the sides of the engine, it may be easier to remove the front wheel and work through the wheel well in some situations. Begin by disconnecting the negative battery cable from the battery and removing the engine cover. Raise the vehicle and support it securely on jackstands. While working under the vehicle, apply penetrating oil to the exhaust pipe-to-manifold studs and nuts, which are usually rusty, and then remove the nuts holding the exhaust pipe(s) to the manifold(s). For the right side manifold on carbureted and TBI models, remove the air filter assembly and heat stove pipe, release the hose clamp, and separate the hose from the AIR system check valve. Detach the spark plug wires from the plugs and brackets and position them out of the way. For the left side manifold on 1986 through 1995 models, follow the oxygen sensor wiring harness to the connector and disconnect it. Detach the spark plug wires from the spark plugs and routing brackets, and position them out of the way. On 1985 through 1990 models, unscrew the AIR pipe fitting at the manifold, release the clamp, and disconnect the hose from the AIR system check valve, then unbolt the AIR pipe bracket from the manifold. For 1996 through 2002 models, unscrew the EGR pipe fittings at the intake and exhaust manifolds, remove the clamp bolt securing it to the intake manifold, and remove the EGR tube from the engine, applying penetrating oil to the pipe fittings to ease removal. Bend the lock tabs back, then remove the mounting bolts and separate the manifold from the head, allowing the heat shields to come off after the bolts are removed. Check the manifold for cracks and ensure the bolt threads are clean and undamaged, making sure the mating surfaces are clean before reinstalling the manifolds using a gasket scraper to remove all carbon deposits. Before installing the exhaust manifold, apply anti-seize compound to the threads of all fasteners, position the manifold, tab washers, and heat shields on the head, and install the mounting bolts. When tightening the mounting bolts, work from the center to the ends using a torque wrench, tightening the bolts in three equal steps until the specified torque is reached. The remaining installation steps are the reverse of removal, and finally, start the engine and check for exhaust leaks.

First, disconnect the cable from the negative battery terminal and on the models with audio system there is an anti-theft feature that should be turned off before disconnecting the battery. Next, unload the engine cover and, at the exhaust manifold, undo the heat stove pipe. Lift the vehicle and then support it with jackstands then remove the oxygen sensor. Label and remove the 4 wires of spark plug, tied up clear of the engine. Remove the nut/bolt that connects the exhaust pipe to the exhaust manifold using a breaker bar/extension bar and apply penetrating oil if there is rust on threads and then drag the exhaust pipe down and use wire and hang it on the frame . Bolt covers and shrouds at the rear, then take off the rear air conditioning compressor bracket before removing the bolts on the exhaust manifold end and the manifold center bolts to isolate manifold from the engine. Remove the exhaust manifold gasket, and check the gasket joining surfaces on the cylinder head and manifold for cleanliness and absence of all existing gasket materials, and carbon deposits on it and also check whether the joining bolt threads of manifold are in good condition. A new exhaust manifold gasket should be applied to the cylinder head and the manifold well seated before the mounting bolts are tightened with fingers just enough to hold the manifold in place. Loosen the bolts gradually in the correct sequence until the reach the torque you want to be at. Join the exhaust pipe back and the air conditioning compressor bracket back and then lower the car. Last of all, put back the remaining pieces in a reverse order of their removal, crank the engine, and look for exhaust loss at the junction between the manifold and cylinder head and between the manifold and the exhaust pipe.

The first step is to disconnect the negative cable from the battery.

Bend the lock tabs back if equipped, then remove the mounting bolts and separate the exhaust manifold from the cylinder head, followed by removing the heat shields.

Disconnect the electrical connector for the oxygen sensor.

The first step is to disconnect the negative cable from the battery.