Avalanche, Express, Savana 2006-2007

Removal & Installation

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CAUTION
Never open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Also, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

4.3L Engine



  1. Drain the radiator until the coolant is below the thermostat level (below the level of the intake manifold).
  2.  
  3. Remove the water outlet elbow assembly from the engine. Remove the thermostat from the engine.
  4.  

To install:

  1. Clean the gasket surfaces on the water outlet elbow and the intake manifold. Use a new gasket when installing the elbow to the manifold.
  2.  
  3. Install the new thermostat making sure the spring side is inserted into the engine. Tighten the thermostat housing bolts to 21 ft. lbs. (28 Nm).
  4.  
  5. Refill the cooling system. Start the engine and check for leaks.

    Click image to see an enlarged view

    Fig. Remove the thermostat housing bolts-4.3L engines



    Click image to see an enlarged view

    Fig. Remove the thermostat housing from the engine-4.3L engines



    Click image to see an enlarged view

    Fig. Remove the thermostat from the housing-4.3L engines



    Click image to see an enlarged view

    Fig. Thermostat housing-4.3L engines

  6.  

4.8L, 5.3L & 6.0L Engines



  1. Remove the air inlet duct.
  2.  
  3. Drain the cooling system.
  4.  
  5. Remove the radiator outlet hose.
  6.  
  7. Remove the thermostat housing bolts.
  8.  
  9. Remove the thermostat from the water pump housing.
    NOTE
    The O-ring seal is integral to the thermostat housing



    Click image to see an enlarged view

    Fig. Thermostat housing-4.8L, 5.3L and 6.0L engines

  10.  

To install:

  1. Install the thermostat to the water pump housing making sure the spring side is inserted into the engine.
  2.  
  3. Install the bolts.
    1. Tighten the bolts to 11 ft. lbs. (15 Nm).
    2.  

  4.  
  5. Install the radiator outlet hose.
  6.  
  7. Fill the cooling system.
  8.  
  9. Install the air inlet duct.
  10.  
  11. Test the system for leaks.
  12.  

6.6L Engine



Thermostat
  1. Drain the engine coolant.
  2.  
  3. Remove the water outlet tube.
  4.  
  5. Remove the bolt for the fuel line bracket.
  6.  
  7. Remove the 4 bolts retaining the thermostat housing cover.
  8.  
  9. Remove the 2 thermostats with the seals.

    Click image to see an enlarged view

    Fig. Exploded view thermostat housing assembly-6.6L engines

  10.  

To install:

  1. Install the 2 thermostats with the seals to the thermostat housing. The rear thermostat (4) has 2 vent valves. Install with the vent valves toward the rear of engine.

    Click image to see an enlarged view

    Fig. View of thermostats in thermostat housing-6.6L engines

  2.  
  3. Install the thermostat housing cover.
    1. Tighten the thermostat housing cover bolts to 15 ft. lbs. (21 Nm).
    2.  

  4.  
  5. Install the fuel line bracket bolt.
    1. Tighten the fuel line bracket and bolt to 15 ft. lbs. (21 Nm).
    2.  

  6.  
  7. Install the water outlet tube.
  8.  
  9. Fill the engine coolant.
  10.  
  11. With the engine idling, add coolant to the radiator until the coolant level reaches the bottom of the filler neck.
  12.  
  13. Install the radiator cap to the radiator.
  14.  
  15. Inspect the coolant system for leaks.
  16.  

Water Outlet Tube
  1. Remove the upper intake manifold sight shield using the following procedure:
    1. Remove the retaining bolt in the front of the shield.
    2.  
    3. Lift-up on the front of the shield.
    4.  
    5. Lift the shield off the rear bracket.
    6.  

  2.  
  3. Drain the engine coolant.
  4.  
  5. Remove the radiator inlet hose from the water outlet tube.
  6.  
  7. Remove the bolt and wiring harness bracket at the thermostat housing.
  8.  
  9. Disconnect the turbocharger coolant hose from the turbocharger bypass valve.
  10.  
  11. Remove the turbocharger bypass valve and sealing washer from the water outlet tube.

    Click image to see an enlarged view

    Fig. Turbocharger bypass valve and sealing washer-6.6L engines

  12.  
  13. Remove the 2 bolts retaining the water outlet tube to the left valve rocker arm cover.
  14.  
  15. Remove the bolt retaining the water outlet tube to the thermostat housing.
  16.  
  17. Remove the water outlet tube.

    Click image to see an enlarged view

    Fig. Water outlet tube-6.6L engines

  18.  
  19. Remove and discard the O-ring seal.
  20.  

To install:

  1. Install a new O-ring seal on the water outlet tube.
  2.  
  3. Lightly lubricate the O-ring seal with coolant.
  4.  
  5. Install the water outlet tube.
  6.  
  7. Install the bolt retaining the water outlet tube to the thermostat housing.
    1. Tighten the water outlet tube to thermostat housing bolt to 15 ft. lbs. (21 Nm).
    2.  

  8.  
  9. Install the 2 bolts retaining the water outlet tube to the valve rocker arm cover.
    1. Tighten the water outlet tube to valve rocker arm cover bolts to 15 ft. lbs. (21 Nm).
    2.  

  10.  
  11. Install the turbocharger bypass valve and sealing washer to the water outlet tube.
    1. Tighten the turbocharger bypass valve to 44 ft. lbs. (60 Nm).
    2.  

  12.  
  13. Connect the turbocharger coolant hose to the turbocharger bypass valve.
  14.  
  15. Install the bolt and wiring harness bracket to the thermostat housing.
    1. Tighten the wiring harness bracket bolt to 71 inch lbs. (8 Nm).
    2.  

  16.  
  17. Install the radiator inlet hose to the water outlet tube.
  18.  
  19. Fill the engine coolant.
  20.  
  21. Install the upper intake manifold sight shield.
    1. Tighten the upper intake manifold shield bolt to 80 inch lbs. (9 Nm).
    2.  

  22.  
  23. With the engine idling, add coolant to the radiator until the coolant level reaches the bottom of the filler neck.
  24.  
  25. Install the radiator cap to the radiator.
  26.  
  27. Inspect the coolant system for leaks.
  28.  

8.1L Engine



  1. Drain the cooling system.
  2.  
  3. Reposition the inlet hose clamp at the water outlet.
  4.  
  5. Remove the inlet hose from the water outlet.
  6.  
  7. Remove the water outlet bolts (2).
  8.  
  9. Remove the water outlet (1).
  10.  
  11. Remove the thermostat (3).
  12.  

To install:

Click image to see an enlarged view

Fig. Thermostat assembly-8.1L engines

  1. Install the thermostat (3).
  2.  
  3. Install the water outlet (1).
  4.  
  5. Install the water outlet bolts (2).
    1. Tighten the bolts to 22 ft. lbs. (30 Nm).
    2.  

  6.  
  7. Install the inlet hose to the water outlet.
  8.  
  9. Position the inlet hose clamp at the water outlet.
  10.  
  11. Fill the cooling system.
  12.  
  13. With the engine idling, add coolant to the radiator until the coolant level reaches the bottom of the filler neck.
  14.  
  15. Install the radiator cap to the radiator.
  16.  
  17. Inspect the coolant system for leaks.
  18.  

 
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