Although air intake manifolds have no moving parts, you may need to remove your Maxima's manifold in order to access another part. High mileage vehicles may experience buildup in the air intake manifold, preventing a proper mixture of gas and air for the combustion process. Air intake manifold configurations differ slightly by engine model, but the process described here applies to single overhead cam (SOHC) engines.
Remove the negative battery cable from your Nissan Maxima. Wait at least 10 minutes in order to prevent the engine cooling fan from causing any potential harm while your hands are near it. Additionally, the engine must be completely cool in order to safely remove the air intake manifold.
Use a screwdriver to remove the hose clamps around the air intake duct. Gently pull the duct from the rest of the manifold.
Disconnect the accelerator cable, cruise control cable, hoses and electrical connections from the throttle body. Coolant may be lost through some of the hoses, which can be prevented by utilizing hose clamps or plugs. Be prepared with a catch pan underneath the hoses to collect any major spills.
Disconnect the spark plug wires from both the spark plugs and the retainers on the plenum. Unbolt the distributor cap. Use a pen and tape to label each wire with its location so that you can easily return each wire to its exact location once the air intake manifold has been put back in place.
Disconnect the ground strap, which is attached to the upper plenum of the air intake manifold and use a socket wrench to loosen the bolts. There are 11 bolts on the upper intake plenum.
Remove the upper plenum, which should still be attached to the throttle body. While the upper plenum of the Maxima's intake manifold is removed, it is a good idea to clean the mounting surfaces as well as the inside of the manifold with a stiff wire and brake cleaner. Use lint-free mechanics' rags to wipe away carbon buildup.
Drain the cooling system by inserting a catch pan beneath the radiator's drain bolt. Unscrew the drain bolt and hold up a 3/8 hose with a funnel on the end of it to direct the coolant to the catch pan. Open the drain fitting with a pair of pliers and remove the radiator cap.
Remove the radiator hose from the thermostat housing and disconnect the electrical connections from the coolant temperature switch and the coolant temperature sensor. Label these connections with tape and pen as described above for the upper plenum hoses and wires.
Remove the bolts to disconnect the coolant pipes at the transmission's end of the intake manifold.
Loosen the bolts on the lower manifold by turning them in 1/4-turn increments until they can be removed by hand. The manifold may need some gentle nudging to be released from the cylinder heads, but do not pry it loose -- doing so can cause damage to the sealing surfaces, leading to vacuum leaks.
Use a scraper to remove any gasket material and sealant from the outer parts of the manifold and cylinder heads. Clean the mating surfaces with lacquer thinner or acetone so that a new gasket can be applied to the lower manifold.
