GM Service Manual Online
For 1990-2009 cars only

Heater Hoses Replacement - Auxiliary Suburban- Front

Removal Procedure

  1. Raise the vehicle.
  2. Support the vehicle with suitable safety stands. Refer to Lifting and Jacking the Vehicle in General Information.

  3. Drain the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
  4. Remove the right front wheelhouse. Refer to Front Fender Replacement in Body Front End.

  5. Object Number: 257123  Size: SH
  6. Remove the bolts in the engine compartment.
  7. Remove the hose (1,2) clamps in the engine compartment.

  8. Object Number: 257126  Size: MH
  9. Remove the bolts from the frame.
  10. Remove the hose clamps from the frame.

  11. Object Number: 257124  Size: SH
  12. Disconnect the heater inlet hose (1) from the tee fittings.
  13. Disconnect the heater outlet hose (2) at the tee fittings.

Installation Procedure


    Object Number: 257124  Size: SH
  1. Connect the heater outlet hose (2) to the tee fittings.
  2. Connect the heater inlet hose (1) to the tee fittings.

  3. Object Number: 257123  Size: SH

    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.

  4. Install the hose (1,2) clamp bolts in the engine compartment.
  5. Tighten
    Tighten the bolts to 17 N·m (13 lb ft).


    Object Number: 257126  Size: MH
  6. Install the hose clamp bolts on the frame.
  7. Tighten
    Tighten the bolts to 17 N·m (13 lb ft).

  8. Install the right front wheelhouse. Refer to Front Fender Replacement in Body Front End.
  9. Add the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
  10. Lower the vehicle.
  11. Inspect the system for leaks.

Heater Hoses Replacement - Auxiliary Suburban- Rear

Removal Procedure

Tools Required

J 38723 Heater Line Quick Connect Separator

  1. Raise the vehicle.
  2. Support the vehicle with suitable safety stands. Refer to Lifting and Jacking the Vehicle in General Information.

  3. Drain the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
  4. Remove the bolts.

  5. Object Number: 257128  Size: LH
  6. Perform the following steps in order to disconnect the rear hose assembly (2) from the front hose assembly.
  7. 4.1. Push the rear hose assembly (2) into the front hose assembly.
    4.2. Insert the J 38723 into the hose in order to release the locking tabs.
  8. Perform the following steps in order to disconnect the rear hose assembly from the auxiliary heater core (4).
  9. 5.1. Push the rear hose assembly into the auxiliary heater core.
    5.2. Insert the J 38723 into the hose in order to release the locking tabs.

Installation Procedure


    Object Number: 257128  Size: LH
  1. Push the rear hose assembly (2) into the front hose assembly until the retainer tabs lock in order to connect the hose assemblies.
  2. Push the rear hose assembly (2) into the auxiliary heater core (4) until the retainer tabs lock in order to connect the hoses with the heater core.
  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.

  4. Install the bolts.
  5. Tighten
    Tighten the bolts to 17 N·m (13 lb ft).

  6. Add the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
  7. Lower the vehicle.
  8. Inspect the system for leaks.

Heater Hoses Replacement - Auxiliary Diesel- Rear

Removal Procedure

  1. Raise the vehicle.
  2. Support the vehicle with suitable safety stands. Refer to Lifting and Jacking the Vehicle in General Information.

  3. Drain the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.

  4. Object Number: 309356  Size: SH
  5. Remove the right front wheelhouse. Refer to Front Fender Replacement in Body Front End.
  6. Remove the bolts in the engine compartment.
  7. Remove the hose clamps in the engine compartment.

  8. Object Number: 257126  Size: MH
  9. Remove the bolts from the frame.
  10. Remove the hose clamps from the frame.

  11. Object Number: 257124  Size: SH
  12. Disconnect the heater inlet (1) hose from the tee fittings.
  13. Disconnect the heater outlet (2) hose at the tee fittings.

Installation Procedure


    Object Number: 257124  Size: SH
  1. Connect the heater outlet (2) hose to the tee fittings.
  2. Connect the heater inlet (1) hose to the tee fittings.

  3. Object Number: 309356  Size: SH

    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.

  4. Install the hose clamp bolts in the engine compartment.
  5. Tighten
    Tighten the bolts to 17 N·m (13 lb ft).


    Object Number: 257126  Size: MH
  6. Install the hose clamp bolts on the frame.
  7. Tighten
    Tighten the bolts to 17 N·m (13 lb ft)

  8. Install the right front wheelhouse. Refer to Front Fender Replacement in Body Front End.
  9. Add the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
  10. Lower the vehicle.
  11. Inspect the system for leaks.