Disconnect the cable from the negative terminal of the battery. Block the rear wheels, set the parking brake, raise the front of the vehicle, and support it securely on jackstands. Disconnect the downstream oxygen sensor connectors. Remove the engine lower splash shield. Unbolt the exhaust pipes at the exhaust manifolds. Lower the vehicle and, working in the engine compartment, disconnect the oxygen sensor's electrical connector. If equipped, remove the exhaust manifold heat shield mounting bolts and take off the heat shield. Remove the mounting bolts and detach the manifold from the
Cylinder Head, ensuring to spray penetrating lubricant onto the bolts and threads before attempting removal. Clean the mating surfaces to eliminate all traces of old gasket material, then inspect the manifold for distortion and cracks, checking for warpage with a precision straightedge. If a feeler gauge thicker than 0.030-inch can be inserted between the straightedge and flange surface, take the manifold to an automotive machine shop for resurfacing. Place the exhaust manifold in position with a new gasket and install the mounting bolts finger tight, ensuring to identify the exhaust manifold gaskets by the correct cylinder designation and the position of the exhaust ports on the gasket. Starting in the middle and working out toward the ends, tighten the mounting bolts in several increments to the specified torque. Install the remaining components in the reverse order of removal. Start the engine and check for exhaust leaks between the manifold and cylinder head and between the manifold and exhaust pipe.