Chevrolet Blazer/Jimmy 1969-1982 Repair Guide

Intake Manifold

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REMOVAL & INSTALLATION



Six Cylinder Engines
1969-76 MODELS

The intake and exhaust manifolds are removed as an assembly.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Disconnect the throttle rods at the bellcrank and remove the throttle return spring.
  6.  
  7. Disconnect the fuel and vacuum lines at the carburetor. Plug the fuel line.
  8.  
  9. Disconnect the crankcase ventilation hose at the rocker arm cover.
  10.  
  11. Disconnect the fuel vapor hose at the canister, if so equipped.
  12.  
  13. Disconnect the exhaust pipe at the manifold flange and discard the packing.
  14.  
  15. Disconnect the EGR valve hose (if equipped).
  16.  
  17. Remove the manifold attaching bolts and clamps and remove the manifold assembly. Discard the gaskets.
  18.  
  19. The manifold assembly can be separated by removing 1 bolt and 2 nuts at the center. Don't tighten these to their final torque until the manifold assembly is installed on the engine.
  20.  
  21. Check the manifold for straightness along the exhaust port faces. If it is distorted more than 0.015 inch it should be replaced. Clean all mounting faces.
  22.  
  23. Installation is the reverse of removal. Use all new gaskets. Bolt torques are given in the Torque Specifications Chart.
  24.  

1975-82 MODELS

These engines use an intake manifold integral with the cylinder head.

V8 Gasoline Engines


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Fig. Fig. 1 Exploded view of the intake manifold mounting and the areas where sealant should be applied during installation



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Fig. Fig. 2 Intake manifold bolt tightening sequence-V8 gasoline engines



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Fig. Fig. 3 To remove the intake manifold, lift the air cleaner housing from the carburetor



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Fig. Fig. 4 Loosen the upper radiator hose clamp ...



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Fig. Fig. 5 ... then disconnect the hose from the thermostat housing



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Fig. Fig. 6 Loosen the fuel line clamp retaining bolt ...



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Fig. Fig. 7 ... then disconnect the fuel line from the carburetor and move it out of the way



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Fig. Fig. 8 After all the lines and linkages have been removed, loosen the manifold bolts ...



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Fig. Fig. 9 ... then remove the manifold assembly from the engine

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Drain the radiator.
  6.  
  7. Remove the alternator lower mounting bolts and position the unit aside.
  8.  
  9. Disconnect:
  10.  
    1. Upper radiator and heater hoses at the manifold.
    2.  
    3. Crankcase ventilation hoses as required.
    4.  
    5. Fuel line at the carburetor.
    6.  
    7. Accelerator linkage at the pedal lever.
    8.  
    9. Vacuum hose at the distributor.
    10.  
    11. Power brake hose at the carburetor base or manifold.
    12.  
    13. Ignition coil (without HEI) and temperature sending switch wires.
    14.  

  11. Remove the distributor cap and mark the rotor position relative to the distributor body and the distributor body relative to the block.
  12.  
  13. Remove the distributor.
  14.  
  15. As required, remove the air cleaner bracket and accelerator bellcrank.
  16.  
  17. Unfasten the manifold-to-head attaching bolts then remove the manifold and carburetor as an assembly.
  18.  

To install:

  1. If the manifold is to be replaced, transfer the carburetor (and mounting studs), water outlet and thermostat (use a new gasket) heater hose adapter, EGR valve (use new gasket) and, if applicable, the choke coil. 1975 and later engines use a carburetor heat choke tube which must be transferred to a new manifold, using a new gasket.
  2.  
  3. Before installing the manifold, thoroughly clean the gasket and seal surfaces of the cylinder heads and manifold.
  4.  
  5. Install the manifold end seals, and the manifold/head gaskets, using a sealing compound around the water passages and where seals butt to gaskets.
  6.  

1974 and later 350 V8 engines require a new intake manifold side gasket. The new gasket has restricted cross-over ports. The 350 2-bbl carbureted engine uses a restricted cross-over gasket on the right-hand side and an open gasket on the left. The 350 4-bbl carbureted engine uses restricted cross-over gaskets on both sides.

  1. When installing the manifold, care should be taken not to dislocate the end seals. It is helpful to use a pilot in the distributor opening. Tighten the manifold bolts to the proper specification in the sequence illustrated.
  2.  
  3. Install the ignition coil.
  4.  
  5. Install the distributor with the rotor in its original location as indicated by the scribe line. If the engine has been disturbed, refer to distributor removal and installation procedure in this section.
  6.  
  7. If applicable, install the alternator upper bracket and adjust the belt tension.
  8.  
  9. Connect all components disconnected in Step 5.
  10.  
  11. Filling the cooling system, start the engine, check for leaks and adjust the ignition timing and carburetor idle speed and mixture.
  12.  

Diesel Engine


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Fig. Fig. 10 Intake manifold bolt tightening sequence-V8 diesel engines

  1. Disconnect the batteries and remove the air cleaner.
  2.  
  3. Remove the crankcase ventilator tubes.
  4.  
  5. Disconnect the fuel lines and remove the secondary fuel filter.
  6.  
  7. Loosen the vacuum pump hold-down clamp and then rotate the pump in order to gain access to the manifold bolt.
  8.  
  9. Remove the intake manifold bolts. The injection line clips are retained by the same bolts.
  10.  
  11. Remove the intake manifold.
  12.  
  13. If any further operations are to be performed while the manifold is off, install screened covers or tape over the holes.
  14.  

To install:

  1. Remove the tape or screened cover if installed.
  2.  
  3. Make sure that the gasket surfaces are clean and install a new gasket.
  4.  

The gasket has an opening for the EGR on light duty applications. On heavy duty applications it has an insert covering the opening.

  1. Install the intake manifold and tighten the bolts to the proper specification in the sequence shown.
  2.  
  3. Install the secondary fuel filter.
  4.  
  5. Install the fuel lines.
  6.  
  7. Installation of the remaining components is in the reverse order.
  8.  

 
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