Intake Manifold: Service and Repair

Fig. 14:

UPPER INTAKE REMOVAL


Removal Remove or Disconnect
(Figure 14)


1. Plastic cover.
2. Wire harnesses, including:
^ Throttle position sensor (TPS).
^ Idle air control (IAC) motor.
^ Manifold absp~ lute pressure (MAP) sensor.
^ Communicator valve.

3. Throttle and TV linkage from upper intake manifold.
4. Ignition coil.
5. PCV hose at rear of upper intake manifold.
6. Vacuum hoses at front and rear of upper intake manifold.
7. Upper intake manifold bolts and studs.
^ Mark the location of all studs for proper reassembly.

8. Upper intake manifold.



LOWER INTAKE REMOVAL

Removal Remove or Disconnect
(Figure 14)

1. Distributor wiring and distributor.
^ Mark the relationship of the distributor housin and rotor for proper reassembly.

2. Upper radiator hose at thermostat housing.
3. Heater hose at lower intake manifold.
4. Fuel supply and return lines at rear of lower intake manifold.
5. Pencil brace (A/C compressor bracket to lower intake manifold).
6. Wire harnesses, including;
^ Fuel injector.
^ Exhaust gas recirculation (EGR) valve.
^ Coolant temperature sensor.

7. Lower intake manifold bolts.
8. Lower intake manifold.


Clean
^ Old pieces of gasket from the gasket surfaces.
^ Excessive carbon build-up in the exhaust passages.
^ Scale and deposits from the coolant passages.
^ EGR passage of excessive carbon deposits.


Inspect
^ Manifold for cracks, broken flanges, and gasket surface damage.


LOWER INTAKE INSTALLATION

Fig. 15:

Install or Connect
(Figures 14 and 15)

1. Gaskets to the cylinder head with the port blocking plates facing the rear of the engine and "this side up" stamping facing up.

2. RTV to the front and rear sealing surfaces on the block.
- Apply a 5 mm (3/16-inch) bead of RTV (GM part number 1052366 or equivalent) to the front and rear of the block.
- Extend the bead 13 mm (1/2-inch) up each cylinder head to seal and retain the gaskets.

3. Lower intake manifold to engine.
^ Apply sealer, GM part number 1052080 or equivalent, to the lower intake manifold bolts.

4. Lower intake manifold bolts.
- Tighten Bolts to 48 N.m (35 ft. lbs.) using the tightening sequence shown in figure 15.

5. Wire harnesses, including;
^ Fuel injector.
^ Exhaust gas recirculation (EGR) valve.
^ Coolant temperature sensor.

6. Pencil brace (NC compressor bracket to lower intake manifold).
7. Fuel supply and return lines to rear of lower intake manifold.
8. Heater hose to lower intake manifold.
9. Upper radiator hose to thermostat housing.
10. Distributor wiring and distributor.
^ Note the relationship of the distributor housing and rotor made at disassembly.



UPPER INTAKE INSTALLATION

Fig. 16:

Install or Connect
(Figures 14 and 16)

1. Upper intake manifold gasket with green sealing lines facing up.
2. Upper intake manifold.
- Use care not to pinch the injector wires between the upper and lower intake manifolds.

3. Upper intake manifold bolts.
- Note the marks made at disassembly for proper stud location.
- Tighten bolts to 14 N.m (124 in. lbs.) using the sequence shown in figure 16.

4. PCV hose to rear of upper intake manifold.
5. Vacuum hoses to front and rear of upper intake manifold.
6. Throttle and TV linkage to upper intake manifold.
7. Ignition coil.
8. Wire harnesses, including:
^ Throttle position sensor (TPS).
^ Idle air control (IAC) motor.
^ Manifold absolute pressure (MAP) sensor.
^ Communicator valve.

9. Plastic cover.