Envoy, Rainer, Trailblazer 2006-2007

Removal & Installation

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4.2L Engine



  1. Remove the necessary coolant from the radiator.
  2.  
  3. Remove the alternator, as outlined in the Engine Electrical Section.
  4.  
  5. Loosen the outlet hose clamp at the thermostat housing. Remove the outlet hose from the thermostat housing.
  6.  
  7. Remove the thermostat housing bolts.
  8.  
  9. Remove the thermostat housing from the engine block.
  10.  
  11. Clean all of the surfaces of the thermostat housing.
  12.  
  13. Clean the sealing surface of the engine block.
  14.  

To install:

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Fig. Thermostat mounting-4.2L engine

  1. Install the thermostat housing to the engine block.
  2.  
  3. Install the thermostat housing bolts and tighten to 89 inch lbs. (10 Nm).
  4.  
  5. Lubricate the inner diameter of the radiator hose with engine coolant.
  6.  
  7. Install the outlet hose to the thermostat housing. Secure the hose with the clamp.
  8.  
  9. Install the alternator.
  10.  
  11. Fill the cooling system with specified coolant and concentration.
  12.  
  13. Inspect all sealing surfaces for leaks after starting the engine.
  14.  

5.3L & 6.0L Engines




NOTE
The thermostat is not serviceable separately. The water pump inlet and thermostat must be replaced as an assembly.

  1. Drain the cooling system to a level below the thermostat.
  2.  
  3. Remove the radiator outlet hose.
  4.  
  5. Remove the water pump inlet bolts.
  6.  
  7. Remove the water pump inlet and thermostat from the water pump.
  8.  

To install:

  1. Install the thermostat and thermostat housing to the water pump.
  2.  
  3. Install the thermostat housing bolts. Tighten the bolts to 11 ft. lbs. (15 Nm).
  4.  
  5. Install the radiator outlet hose.
  6.  
  7. Properly fill the engine cooling system and check for leaks.
  8.  

 
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