How to Replace the Intake Manifold in a Lincoln Navigator

by Editorial TeamUpdated November 07, 2017

Items you will need

  • Mechanic's tool set

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How to Replace the Intake Manifold in a Lincoln Navigator. The Lincoln Navigator is the first full-size luxury SUV offered by a domestic auto maker. Because of its size and flash, it was regarded for its first few years as a status symbol. The process of removing and installing the intake manifold is the same on the 4.6L, 5.4L and 6.8L engines, with the exception of the 5.4L DOHC and the 5.4L Lightning.

Remove the Intake Manifold

Pull the negative battery cable from the terminal. Drain the coolant from the cooling system and relieve the pressure in the fuel system.

Disconnect the upper radiator hose from the manifold. Disconnect the air cleaner outlet tube and the accelerator cable to the throttle body cam. Pull all vacuum hoses, fuel lines and wires from the throttle body and the manifold.

Remove the bracket for the brake booster hose and the EGR valve tube. Disconnect the fuel injector electrical connectors.

Label each spark plug wire and remove it. Remove the alternator, the accessory drive belt and the power steering oil reservoir bracket. Pull the heater water hose from the manifold.

Loosen and remove the intake manifold bolts. Lift the manifold from the engine and disconnect the IM Tuning Valve (IMTV) connector. Pull the upper intake gaskets and discard them.

Use a ratchet to remove the upper-to-lower manifold bolts then separate the two units. Remove the gasket and discard it.

Install the Intake Manifold

Set the upper manifold onto the lower manifold. Put the bolts into position and but do not tighten them. Follow the tightening sequence to make two passes over the bolts to tighten them. Apply 18 inch pounds on the first pass and 6 to 8 foot pounds on the second (see Tips).

Place the two gaskets for the upper intake manifold on the cylinder heads. Put the upper intake manifold on the engine and set the bolts loosely in place. Reconnect the IMTV.

Make sure the thermostat housing is correctly positioned, then install the thermostat. Tighten the bolts in sequence. Use 18 inch pounds on the first pass and 15 to 22 inch ft lbs on the second.

Reconnect the heater water hose. Put the power steering bracket in place and install the pump bracket bolts to 71 to 107 inch foot. Attach all the fuel lines, vacuum hoses, electrical connections and coolant hoses to the manifold and throttle body assembly.

Install the accessory drive belt, the alternator, spark plug wire, EGR manifold tube. Tighten the fittings to 26 to 33 foot pounds.

Connect the accelerator cable to the throttle body, then connect the engine air clearer outlet tube and the heater water hose. Fill the cooling system with the appropriate amount and type of coolant.

Connect the negative battery cable. Start the engine and allow it to run for a few minutes. Check for leaks of fuel, coolant or vacuum.


Tighten the intake manifold bolts in sequence. Start with the middle bolt on the side of the manifold farthest from the front of the vehicle. Then move to the bolt opposite it closest to the front of the vehicle. Then tighten the bolt to the left and then to the right of the first bolt. Continue alternating sides in a criss-cross pattern.


Be aware that dogs and cats are attracted to and will drink coolant left in open containers or puddled on the floor. Ingestion is often fatal. Drain coolant into a container that can be sealed. Reuse the coolant unless it is contaminated or several years old.

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