GM 14091886 Manifold

Disconnect the negative battery cable from the battery. Caution: On models equipped with the Delco Loc II audio system, make sure the lockout feature is turned off before performing any procedure that requires disconnecting the battery. Unplug the oxygen sensor. Remove the manifold heat shields. Raise the vehicle and securely support it on jackstands, then remove the exhaust pipe-to-manifold nuts. The nuts are usually rusted in place, so penetrating oil should be applied to the stud threads before attempting to remove them. Loosen them a little at a time, working from side to side to prevent the flange from jamming. Remove the exhaust manifold brace. Separate the exhaust pipe flange from the manifold studs, then pull the pipe down slightly to break the seal at the manifold joint. Loosen the exhaust manifold mounting nuts 1/4-turn at a time, working from the inside out, until they can be removed by hand. Separate the manifold from the head and remove it. The manifold and cylinder head mating surfaces must be clean when the manifold is reinstalled. Use a gasket scraper to remove all traces of old gasket material and carbon deposits. Using a new gasket, install the manifold and hand tighten the fasteners. Working from the center out following the recommended sequence, tighten the bolts/nuts. The remaining installation steps are the reverse of removal.