Intake Manifold Replacement

Fig. 1 Intake and Exhaust Manifolds:

WARNING: Release fuel system pressure before servicing fuel system components. Service vehicles in well ventilated areas and avoid ignition sources. NEVER smoke while servicing the vehicle.

INTAKE MANIFOLD SERVICE
The intake system has a large air intake plenum of aluminum alloy and a cross type intake manifold Fig. 1.

The exhaust manifolds are made of ductile cast iron with the front bank and rear bank independent of each other. The exhaust from the front bank exhaust manifold is fed through a exhaust crossover pipe to be combined with the rear bank exhaust at the exhaust outlet to the exhaust pipe.

Fig. 2 Auxiliary Jumper Terminal:

INTAKE PLENUM / MANIFOLD - REMOVAL
1. Disconnect negative cable from auxiliary jumper terminal Fig. 2.
2. Release fuel system pressure. Refer to Fuel System Pressure Release procedure.

WARNING: Wrap shop towels around hose to catch any gasoline spillage.

3. Disconnect fuel supply tube from rail.

Fig. 4 Intake Manifold Sensors And Left Manifold Support Bolt:

4. Unplug connectors from MAP and intake air temperature sensors.
5. Remove plenum support bracket bolt located rearward of MAP sensor.

Fig. 3 Air Inlet Resonator:

6. Remove bolt holding air inlet resonator to intake manifold.
7. Loosen throttle body air inlet hose clamp.
8. Release snaps holding air cleaner housing cover to housing.
9. Remove air cleaner cover and inlet hoses from engine.

Fig. 5 Throttle Position Sensor:

Fig. 6 Idle Air Control Monitor:

10. Unplug TPS and idle air control motor connectors (Figs. 5 and 6).

Fig. 7 Throttle Cable Attachment:

11. Squeeze retainer tab on throttle cable and slide cable out of bracket.
12. Slide Speed control cable out of bracket, if equipped.

Fig. 8 EGR Tube And Right Manifold Support Bolt:

13. Remove EGR tube from intake manifold -- Fig. 8.
14. Remove plenum support bracket bolt located rearward of EGR tube -- Fig. 8.
15. Remove 7 bolts holding upper intake plenum and remove plenum Fig. 1.
16. Disconnect electrical connectors from fuel injectors.

Fig. 9 Fuel Rail Attachment:

17. Remove 4 bolts holding fuel rail Fig. 9.

Fig. 10 Fuel Rail Spacers:

18. Lift fuel rail off engine. There are spacers under each fuel rail bolt Fig. 10.
19. Remove lower intake manifold attaching bolts. Remove intake manifold.

CLEANING AND INSPECTION
1. Discard gasket and clean all gasket surfaces of manifold to cylinder heads.
2. Check upper and lower manifold gasket surfaces for flatness with straight edge. Surface must be flat within 0.15 mm per 300 mm (0.006 in. per foot) of manifold length.
3. Inspect manifolds for cracks or distortion. Replace manifold if necessary.

Fig. 11 Intake Manifold Tightening Sequence:

INSTALLATION
1. Install intake manifold with new gaskets. Tighten in sequence shown in Fig. 11 to 28 Nm (250 in. lbs.).
2. Apply a light coating of clean engine oil to the 0-ring on the nozzle end of each injector.
3. Insert fuel injector nozzles into openings in intake manifold. Seat the injectors in place. Tighten fuel rail bolts to 12 Nm (8 ft. lbs.).
4. Attach electrical connectors to fuel injectors.
5. Connect fuel supply tube to fuel rail.
6. Install new gasket and position upper intake plenum. Tighten plenum bolts to 18 Nm (13 ft. lbs.) torque.
7. Install bolts at plenum support brackets. Tighten bolts to 18 Nm (13 ft. lbs.).
8. Install EGR tube to plenum. Tighten EGR tube to intake manifold plenum screws to 11 Nm (95 in. lbs.) torque.
9. Install throttle cables.
10. Attach electrical connectors to sensors.
11. Tighten air inlet tube clamps to 3 ± 1 Nm (25 ± 5 in. lbs.).
12. Connect negative terminal to auxiliary jumper terminal Fig. 2.