GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Tahoe - 2WD 🢒 Engine 🢒 Engine Cooling 🢒 Thermostat Housing Crossover Replacement

Removal Procedure

    Object Number: 658266 Size: SH
  1. Remove the upper intake manifold sight shield using the following procedure:
    2. 1.1. Remove the retaining bolt in the front of the shield.
    1.2. Lift-up on the front of the shield.
    1.3. Lift the shield off the rear bracket.
  2. Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  3. Drain the engine coolant. Refer to Cooling System Draining and Filling .
  4. Remove the upper fan shroud. Refer to Engine Coolant Fan Upper Shroud Replacement .
  5. Remove the drive belt. Refer to Drive Belt Replacement in Engine Mechanical - 6.6 L.

    6. Object Number: 652573 Size: SH
  6. Disconnect the A/C compressor clutch electrical connector.
  7. Disconnect the A/C cut out switch electrical connector.
  8. Remove the A/C compressor mounting bolts.
  9. Move the A/C compressor with the hoses attached to the right side of the engine compartment.

    10. Object Number: 666693 Size: SH
  10. Remove the nut retaining the generator positive cable to the generator.
  11. Remove the positive cable from the generator.
  12. Remove the clip holding the positive cable to the engine front cover.
  13. Remove the bolt retaining the battery positive cable junction block to the power steering pump.
  14. Move the generator positive cable and the junction block bracket aside.
  15. Disconnect the generator electrical connector.
  16. Disconnect the engine coolant temperature (ECT) sensor electrical connector.

    17. Object Number: 669241 Size: SH
  17. Remove the power steering pump mounting bracket and secure to the side.
    18. • Do not remove the power steering pump from the bracket.
    • The hoses and battery cables can remain on the power steering pump.

    Object Number: 698198 Size: SH
  18. Remove the bolts retaining the fuel bleed valve and PCV oil separator bracket from the generator mounting bracket.

    19. Object Number: 669244 Size: SH
  19. Remove the heater outlet hose bracket bolt from the generator bracket.
  20. Remove the ribbed idler pulley.
  21. Remove the generator mounting bracket and secure to the side.
    22. • The generator does not require removal.
    • The drive belt tensioner does not require removal.
  22. Remove the oil fill tube. Refer to Oil Filler Tube Replacement in Engine Mechanical - 6.6 L.
  23. Remove the water outlet tube. Refer to Water Outlet Tube Replacement .

    24. Object Number: 699325 Size: SH
  24. Remove the bolt retaining the heater pipe to the fuel filter assembly.
  25. Remove the bolt retaining the heater pipe to the thermostat housing crossover.
  26. Remove the heater pipe with O-ring seal from the crossover.

    27. Object Number: 699335 Size: SH
  27. Remove the hose and clamp from the turbocharger outlet coolant pipe to thermostat bypass pipe.
  28. Remove the fuel line bracket from the thermostat housing crossover.
  29. Remove the cooling fan pulley. Refer to Cooling Fan Pulley Replacement

    30. Object Number: 654526 Size: SH
  30. Remove the 2  thermostat housing crossover bolts and 2 nuts from the left cylinder head.
  31. Remove the 2 thermostat housing crossover bolts and 2 nuts from the right cylinder head.
  32. Remove the bypass pipe to water pump bolts.
  33. Remove the thermostat housing crossover with the bypass pipe.
  34. Remove the bypass pipe to water pump O-ring.

    35. Object Number: 660428 Size: SH
  35. Remove the bypass pipe from the thermostat housingcrossover.
  36. Remove the O-ring from the bypass pipe.

Inspection and Repair Procedure

    Object Number: 660424 Size: SH
  1. If required, remove the thermostat cover bolts.
  2. Remove the thermostat cover.
  3. Remove the thermostats with seals.
  4. Remove the thermostat seals.
  5. Remove the ECT sensor if replacing the thermostat housing crossover.

    6. Object Number: 663758 Size: SH
  6. Clean the water crossover.
  7. Clean the thermostat housing crossover mating surfaces.
  8. Inspect the thermostat housing crossover for cracks.
  9. Inspect the thermostat housing crossover mating surfaces for damage.
  10. Replace the thermostat housing crossover if any damage is found.

    11. Object Number: 660424 Size: SH
  11. Install the thermostats with the seals.

    12. The thermostat with the vent valves goes toward the rear of the engine. Install with the vent valves towards the rear of the engine.

  12. Install the thermostat cover and gasket.

    13. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  13. Install the thermostat cover bolts.

    14. Tighten
    Tighten the thermostat cover bolts to 21 N·m (15 lb ft).

  14. If removed, install the ECT sensor.

    15. Tighten
    Tighten the ECT sensor to 33 N·m (24 lb ft).

Installation Procedure

    Object Number: 660428 Size: SH
  1. Install a new O-ring to the bypass pipe. Lubricate the O-ring with coolant.
  2. Install the bypass pipe to the thermostat housing crossover.

    3. Object Number: 654526 Size: SH
  3. Install new thermostat crossover gaskets.
  4. Install a new O-ring for the bypass pipe to the water pump.
  5. Install the thermostat crossover with the bypass pipe.

    6. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  6. Install the bypass pipe to water pump bolts.

    7. Tighten
    Tighten the bypass pipe to water pump bolts to 21 N·m (15 lb ft).

  7. Install the thermostat crossover bolts and nuts.

    8. Tighten
    Tighten the thermostat crossover bolts and nuts to 21 N·m (15 lb ft).

  8. Install the fuel line bracket and bolt.

    9. Tighten
    Tighten the fuel line bracket bolt to 21 N·m (15 lb ft).


    Object Number: 699335 Size: SH
  9. Install the hose and clamp from the turbocharger outlet coolant pipe to thermostat bypass pipe.

    10. Object Number: 699325 Size: SH
  10. Install a new O-ring seal to the heater pipe.
  11. Install the heater pipe to the thermostat housing crossover.
  12. Install the bolt retaining the heater pipe to the thermostat housing crossover.

    13. Tighten
    Tighten the heater pipe bolt to 21 N·m (15 lb ft).

  13. Install the bolt retaining the heater pipe to the fuel filter assembly.

    14. Tighten
    Tighten the heater pipe bracket bolt to 21 N·m (15 lb ft).


    Object Number: 669244 Size: SH
  14. Install the generator mounting bracket and bolts.

    15. Tighten
    Tighten the generator mounting bracket bolts to 50 N·m (37 lb ft).

  15. Install the ribbed idler pulley and the bolt.

    16. Tighten
    Tighten the idler puller bolt to 43 N·m (32 lb ft).

  16. Install the heater outlet hose bracket bolt.

    17. Tighten
    Tighten the bracket bolt to 21 N·m (15 lb ft).


    Object Number: 698198 Size: SH
  17. Install the nuts retaining the fuel bleed valve and PCV oil separator bracket from the generator mounting bracket.

    18. Tighten
    Tighten the bracket nuts to 25 N·m (18 lb ft).


    Object Number: 669241 Size: SH
  18. Install the power steering pump mounting bracket and bolts.

    19. Tighten
    Tighten the power steering pump mounting bracket bolts to 46 N·m (34 lb ft).

  19. Install the water outlet tube. Refer to Water Outlet Tube Replacement .

    20. Object Number: 666693 Size: SH
  20. Position the generator positive cable.
  21. Install the generator positive cable in the clip on the engine front cover.
  22. Install the generator positive cable and the retaining nut to the generator.

    23. Tighten
    Tighten the generator positive cable nut to 9 N·m (80 lb in).

  23. Install the battery positive cable junction block bracket and bolt to the power steering pump.

    24. Tighten
    Tighten the junction block bracket bolt to 9 N·m (80 lb in).

  24. Connect the generator electrical connector.

    25. Object Number: 652573 Size: SH
  25. Position the A/C compressor.
  26. Install the A/C compressor mounting bolts.

    27. Tighten
    Tighten the A/C compressor mounting bolts to 50 N·m (37 lb ft).

  27. Connect the A/C cut out switch electrical connector.
  28. Connect the A/C clutch electrical connector.
  29. Install the drive belt. Refer to Drive Belt Replacement in Engine Mechanical - 6.6 L.
  30. Install the upper fan shroud. Refer to Engine Coolant Fan Upper Shroud Replacement .
  31. Fill the engine coolant. Refer to Cooling System Draining and Filling .
  32. Connect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.

    33. Object Number: 658266 Size: SH
  33. Install the upper intake manifold sight shield.

    34. Tighten
    Tighten the upper intake manifold shield bolt to 9 N·m (80 lb in).