GM Service Manual Online
For 1990-2009 cars only

Coolant Bypass Valve Replacement 4.3L, 4.8L, 5.3L, 6.0L

Tools Required

J 38185 Hose Clamp Pliers

Removal Procedure

  1. Remove the upper fan shroud. Refer to Engine Coolant Fan Upper Shroud Replacement .

  2. Object Number: 834256  Size: SH
  3. Drain the engine coolant. Refer to Cooling System Draining and Filling .
  4. If equipped with 4.8L, 5.3L or 6.0L; remove the engine cover. Refer to Engine Cover Replacement
  5. Remove cowl water drain nuts.
  6. Remove cowl water drain.
  7. Remove the heater inlet hose clamp and the heater outlet hose clamp from the heater core.
  8. Remove the upper heater inlet hose and the upper heater outlet hose from the heater core.
  9. Remove the lower heater inlet hose clamp and the lower heater outlet hose clamp from the outlet of the coolant bypass valve (4) using the J 38185 .
  10. Remove the lower heater inlet hose and the lower heater inlet hose from the inlet of the coolant bypass valve.
  11. Remove the vacuum hose from the coolant bypass valve.

Installation Procedure


    Object Number: 834256  Size: SH
  1. Install the coolant bypass valve (4).
  2. Install the vacuum hose to the coolant bypass valve.
  3. Install the lower heater inlet hose (5) and the lower heater outlet hose (6) to the inlet of the coolant bypass valve (4).
  4. Install the lower heater inlet hose clamp and the lower heater outlet hose clamp to the inlet of the coolant bypass valve using the J 38185 .
  5. Install the upper heater inlet hose and the upper heater outlet hose from the heater core.
  6. Install the heater inlet hose clamp and the heater outlet hose clamp from the heater core.
  7. Install cowl water drain.
  8. Install cowl water drain nuts.
  9. If equipped with 4.8L, 5.3L or 6.0L; install the engine cover. Refer to Engine Cover Replacement
  10. Fill the cooling system. Refer to Cooling System Draining and Filling .
  11. Install the upper fan shroud. Refer to Engine Coolant Fan Upper Shroud Replacement .

Coolant Bypass Valve Replacement 6.6L

Tools Required

J 38185 Hose Clamp Pliers

Removal Procedure

  1. Remove the air cleaner assembly. Refer to Air Cleaner Assembly Replacement .
  2. Remove the upper fan shroud. Refer to Engine Coolant Fan Upper Shroud Replacement .
  3. Remove the accumulator. Refer to Air Conditioning Accumulator Replacement .
  4. Remove the vacuum hose from the coolant bypass valve.

  5. Object Number: 1654002  Size: SH
  6. Drain the engine coolant. Refer to Cooling System Draining and Filling .
  7. Reposition the heater inlet hose clamp and the heater outlet hose clamp from the coolant bypass valve using the J 38185 .
  8. Remove the heater inlet hose and the heater outlet hose from the coolant bypass valve.

  9. Object Number: 1654011  Size: SH
  10. Reposition the heater inlet hose clamp and the heater outlet hose clamp from the heater core using the J 38185 .
  11. Remove the heater inlet hose and the heater outlet hose from the heater core.
  12. Remove the coolant bypass valve assembly from the vehicle.

Installation Procedure


    Object Number: 1654011  Size: SH
  1. Install the coolant bypass valve assembly to the vehicle.
  2. Install the heater inlet hose and the heater outlet hose to the heater core.
  3. Reposition the heater inlet hose clamp and the heater outlet hose clamp to the heater core using the J 38185 .

  4. Object Number: 1654002  Size: SH
  5. Install the heater inlet hose and the heater outlet hose to the coolant bypass valve.
  6. Reposition the heater inlet hose clamp and the heater outlet hose clamp to the coolant bypass valve using the J 38185 .
  7. Install the vacuum hose to the coolant bypass valve.
  8. Install the accumulator. Refer to Air Conditioning Accumulator Replacement .
  9. Fill the cooling system. Refer to Cooling System Draining and Filling .
  10. Install the upper fan shroud. Refer to Engine Coolant Fan Upper Shroud Replacement .
  11. Install the air cleaner. Refer to Air Cleaner Assembly Replacement .