This procedure applies to both the front and rear exhaust manifold/catalytic converter assemblies. Begin by disconnecting the cable from the negative terminal of the battery. Raise the front of the vehicle and support it securely on jack stands, then remove the engine lower splash shield. If removing the exhaust manifold/catalytic converter from the front cylinder head, drain the coolant, remove the coolant reservoir, and take out the radiator fan shroud and fan motor assembly, followed by the air conditioning compressor. For the rear cylinder head, remove the upper intake manifold, alternator, and right drive axle assembly. Disconnect the upstream oxygen sensor electrical connector and remove the upstream sensor from the manifold. Remove the heat shield fasteners and the heat shield from the exhaust manifold. Spray penetrating oil on all upper and lower exhaust manifold fasteners and allow it to soak in. Remove the front exhaust pipe fasteners. Disconnect the downstream oxygen sensor electrical connector and remove the downstream sensor from the manifold. Unbolt the exhaust manifold(s) from the cylinder head(s), working from the ends toward the middle, and slip the manifold(s) off the mounting studs. Carefully inspect the manifold(s) for cracks and damage. Use a scraper to remove all traces of old gasket material and carbon deposits from the manifold and cylinder head mating surfaces. If the gasket was leaking, check the manifold for warpage on the cylinder head mounting surface by placing a straightedge over the surface and trying to insert a feeler gauge; if the clearance exceeds the limit, have the manifold resurfaced at an automotive machine shop. Position a new gasket over the cylinder head studs, install the manifold(s), and thread the mounting nuts into place. Working from the center out, tighten the exhaust manifold nuts to the specified torque. Reinstall the remaining parts in the reverse order of removal, using new gaskets when connecting the front exhaust pipe. Finally, run the engine and check for exhaust leaks.
