Intake Manifold Replacement - GMC G Service Manual

INTAKE MANIFOLD REPLACEMENT

H Remove or Disconnect
1. Battery negative cable.
2. Engine cover (G-models).
3. Air cleaner.
• Drain the cooling system.
4. AIR crossover hose (G-models with TBI engines).
5. Heater hose and upper radiator hose at the intake
manifold.
6. Generator bracket at the manifold.
7. Vacuum hoses at the manifold, carburetor or TBI unit,
and EGR valve.
8. Electrical connections at the manifold and carburetor
or TBI unit.
9. Fuel line(s) at the carburetor or TBI unit.
10. Accelerator, cruise control, and TVS cables (as
equipped).
11. Distributor. Refer to ENGINE ELECTRICAL
(SEC. 6D).
12. Air conditioning compressor and bracket; lay aside (if
equipped) (except G-models with TBI engines).
13. Brake booster vacuum pipe.
14. Components as follows on TBI engines:
• Coil wires.
• Emission control sensors and bracket on right
side.
• Cruise control transducer and bracket (if
equipped).
• Fuel line bracket at rear of manifold. Move the
fuel lines aside.
• Bracket at rear of belt idler (G-models).
15. Carburetor or TBI unit (if necessary).
16. Intake manifold bolts.
17. Intake manifold.
18. Gaskets.
Clean
• Old gasket and RTV from the block, heads, and
intake manifold. Remove all RTV that is loose or will
cause interference at assembly.
• Excessive carbon deposits from the exhaust and
EGR passages.
• Excessive scale and deposits from the coolant
passages.
| P I Inspect
• Manifold for cracks and gasket surface damage.
SMALL BLOCK 6A4-9
H Install or Connect (Figures 8 and 9)
1. Gaskets to the cylinder head.
2. RTV to the front and rear sealing surfaces on the
block (figure 8). Apply a 5 mm (3/16-inch) bead of
RTV to the front and rear of the block as shown.
Extend the bead 13 mm (1/2-inch) up each cylinder
head to seal and retain the gaskets.
3. Intake manifold to the engine.
4. Intake manifold bolts.
Tighten
• Intake manifold bolts to 48 N*m (35 ft. lbs.). Use
the tightening sequence shown in figure 9.
5. Carburetor or TBI unit (if removed).
6. Components as follows on TBI engines:
• Bracket at rear of belt idler (G-models).
• Fuel line bracket at rear of manifold.
• Cruise control transducer and bracket (if
equipped).
• Emission control sensors and bracket on right
side.
• Coil wires.
7. Brake booster vacuum pipe.
8. Air conditioning compressor and bracket (if removed).
Refer to AIR CONDITIONING (SEC. 1B).
9. Distributor. Refer to ENGINE ELECTRICAL
(SEC. 6D).
10. Accelerator, cruise control, and TVS cables (as
equipped).
11. Fuel line(s) at the TBI unit or carburetor.
12. Electrical connections at the intake manifold and car­
buretor or TBI unit.
13. Vacuum hoses at the manifold, carburetor or TBI unit,
and EGR valve.
14. Generator bracket at the manifold.
15. Heater hose and upper radiator hose at the manifold.
16. AIR crossover hose (G-models with TBI engines).
17. Air cleaner.
18. Engine cover (G-models).
19. Battery negative cable.
• Fill the cooling system with the proper quantity and
grade of coolant. Refer to MAINTENANCE AND
LUBRICATION (SEC. OB).
• Evacuate and charge the air conditioning system.
Refer to AIR CONDITIONING (SEC. 1B).