GM 14091886 Manifold

To start the front manifold removal, disconnect first the negative battery cable and remove air cleaner assembly, inlet hose and mass air flow sensor. Allow to cool engine off, drain cooling system, and if needed, disconnect coolant bypass tube. Remove cooling fan assembly and oil dipstick tube mounting bolt. For earlier models with tubular steel manifolds, disengage front manifold extension pipe near rear manifold. For later models with cast iron manifolds, unbolt crossover pipe from front manifold. Lift off the manifold heat shield and its attaching bolts then remove the manifold from cylinder head. Clean gasket surfaces; also visually inspect the manifold for warping or cracking; have it machined flat again at an automotive machine shop if required. Install the new gasket into position on the manifold; tighten down screw gradually right from middle as you go towards edges. Begin reassembling other components in a reverse order then check for leakages in exhaust system. When removing the rear manifold begin by disconnecting the negative battery cable and allowing time for engine to cool down. Disconnect EGR tube from exhaust manifold and remove throttle cables as well as TV brackets when necessary. Take out heat shield and undo crossover pipe (or front manifold extension pipe) from rear of engine block Unplug oxygen sensor wire then if replacing manifolds move sensors onto new ones Set parking brake, block rear wheels then raise vehicle's front side on jackstands With vehicle raised up slightly higher than normal working level beneath it- Use penetrating oil in case of difficulties while taking out two exhaust pipe-to-manifold bolts Loosen all nuts including those which hold down exhaust pipes to their flanges under car floor Remove exhaust manifolds Check mating surfaces for perfect alignment; check both for cracks by closely examining them; make machining flat at an auto-machine workshop possible Put new gasket onto place on top of these manifolds finger-tightening fasteners before reasonably tightening from inside out Begin reassembling other components in a reverse order then run engine to check for smoke.

Disconnect the negative 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 lead. Remove the drive belt and the alternator. Raise the front of the vehicle, support it securely on jackstands, and apply the parking brake. Block the rear wheels to prevent the vehicle from rolling off the jackstands. Unbolt the exhaust pipe from the manifold. Lower the vehicle. Remove the eight exhaust manifold-to-cylinder head nuts/bolts, pull the manifold off the engine, and lift it out of the exhaust pipe flange. Remove and discard the gasket. Scrape off all traces of gasket material from the exhaust manifold and cylinder head mating surfaces. Clean all bolt and stud threads before installation. Use a wire brush on the manifold mounting studs, and a tap works well for cleaning the cylinder head bolt holes. If installing a new manifold, transfer the oxygen sensor from the old manifold to the new one. Installation is the reverse of removal. Be sure to use a new gasket and tighten the nuts/bolts. Work in a spiral pattern from the center out.

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.