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 .