GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Chevy C Cab/Chassis HD (GMT 400) 🢒 Engine 🢒 Engine Cooling 🢒 Thermostat Housing Crossover Replacement

Removal Procedure

    Object Number: 358421 Size: SH
  1. Drain the coolant from the radiator. Refer to Cooling System Draining and Filling .
  2. Remove the upper intake manifold cover.

    3. Object Number: 26963 Size: SH
  3. Disconnect the engine coolant temperature (ECT) sensor electrical connector.

    4. Object Number: 26943 Size: SH
  4. If replacing the thermostat housing crossover remove the ECT sensor.

    5. Object Number: 332048 Size: SH
  5. Disconnect the bypass hose from the thermostat housing crossover.

    6. Object Number: 729060 Size: SH
  6. Disconnect the radiator inlet hose from the thermostat housing water outlet.

    7. Object Number: 257112 Size: SH
  7. Disconnect the heater hose (1) from the thermostat housing crossover.

    8. Object Number: 66572 Size: SH
  8. Remove the fuel bleed valve and stud/nut.
  9. Remove the thermostat housing crossover studs and the bolts.
  10. Remove the coolant crossover housing assembly from the vehicle.
  11. Clean the crossover housing sealing surfaces.
  12. If thermostats require replacing refer to Engine Coolant Thermostat Replacement .

Installation Procedure

    Object Number: 66572 Size: SH
  1. Install the new gaskets.
  2. Install the thermostat housing crossover.

    3. 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.

  3. Install the studs and the bolts.

    4. Tighten
    Tighten the studs and the bolts to 42 N·m (31 lb ft).

  4. Instal the fuel bleed valve and stud/nut.

    5. Tighten
    Tighten the stud/nut to 42 N·m (31 lb ft).


    Object Number: 332048 Size: SH
  5. Connect the bypass hose to the thermostat housing crossover.

    6. Object Number: 257112 Size: SH
  6. Connect the heater hose (1) to the thermostat housing crossover.

    7. Object Number: 729060 Size: SH
  7. Connect the radiator inlet hose to the thermostat housing water outlet.

    8. Object Number: 26943 Size: SH
  8. If removed, install the ECT sensor.

    9. Tighten
    Tighten the ECT sensor to 25 N·m (18 lb ft).


    Object Number: 26963 Size: SH
  9. Connect the engine coolant temperature (ECT) sensor electrical connector.

    10. Object Number: 358421 Size: SH
  10. Fill the cooling system with coolant. Refer to Cooling System Draining and Filling .
  11. Attach the surge tank cap to the surge tank. Make sure that the cap arrows line up with the overflow tube.
  12. Inspect the cooling system for leaks.
  13. Install the upper intake manifold cover.