Q: How to remove and install the Intake Manifold in 3.8L V6 engine on 1996 Pontiac Grand Prix?
A: To get to the manifold, first, pull off the fuel system pressure, and unbuckle the negative terminal battery; in case of a Theftlock audio system, there should be a lockout button. First, disconnect the air intake duct, the mass airflow sensor, and the throttle body from the vehicle Next, pull out the power steering pump-to-manifold brace, and the acoustic cover in the 1995 and other later models. Take off the fuel rail and injectors, also, remove the upper plenum if it is a 1995 and later model. Open the upper/top panel and unclasp the tabs of the control cables and pull to disconnect them from the brackets, eliminate the drivebelt, and disengage the alternator and brackets. remove the coolant from the vehicle, remove the coolant tubes and hoses from the manifold, and remove the ignition module/coil assembly, there is EGR tube from the lower manifold on 1995 and later engines if it is installed. Detaching the vacuum and electrical connectors at the intake manifold can be done now together with the removal of the manifold mounting bolt and nut and the separation of the manifold as well from the engine part; this should however be done very carefully to avoid prying between gasket surfaces since this may damage the gasket. Installation should see to it that the mating surface of the cylinder head, block, manifold are clean, utilizing acetone or gasket removal solution if needed. As for opening the aluminum heads, it is useful to eliminate old gasket material with a gasket scraper without harming the aluminum-then cleaning the spaces with a paper moistened in lacquer thinner or acetone. The threads in the bolt holes should be chased with a tap and one should use the compressed air to remove the debris while putting on safety glasses. If using steel manifold gaskets, coat both sides of the gasket with contact cement or spray adhesive and install the gaskets; use RTV sealant on the new manifold-to-block seals. Place the manifold with as much control as possible, apply the thread lock compound to the male threads of the bolts and install the bolts loosely. Also, as recommended torque the bolts in two steps followed by reinstallation of the rest of the hardware in the reverse order noting if a new plenum to lower intake gasket is used. Last but not least, top up the oil and filter, and the coolants, crank the engine and look out for oil and vacua leaks.