GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1997 🢒 GMC P62 Commercial Chassis 🢒 Engine 🢒 Engine Cooling 🢒 Cooling System Draining and Filling

Draining
  1. Place a drain pan under the radiator drain cock.
  2. Install a tube on the drain cock.
  3. Place the end of the tube in the drain pan.
  4. When the cooling system is cool, remove the radiator cap.
  5. Open the drain cock completely.
  6. Let the cooling system drain until the flow stops.
  7. Place a drain pan under the engine.
  8. Remove the drain plug in the engine block.
  9. Let the engine block drain until the flow stops. There may be more drainage from the radiator at this time.
  10. Replace the engine block drain plug.
  11. Close the radiator drain cock.

Filling
  1. Check the radiator drain cock to be sure it is closed.
  2. Check the engine drain plug to be sure it is tight.
  3. Premix the anti-freeze with clear water in a 44/56 (50/50 in Canada) ratio.
    4. • If the old coolant is being used, check it for a 44/56 glycol/water mix (50/50 in Canada) and make sure it is clean.
    • There will be fewer problems with sediment and scale deposits if distilled water is used instead of tap water.
  4. Place a large top funnel in the radiator fill hole.
  5. Slowly pour in the coolant. The filling may be slowed because the thermostat is closed.
  6. After the cooling system is filled to 6.5 mm (1/2 in) below the fill hole, start the engine and let the cooling system warm up.

    7. When the thermostat opens, the coolant level may drop. If the level drops, add coolant until the level returns to the fill hole.

  7. Replace the radiator cap.
  8. Check the coolant level in the surge tank. Add coolant if necessary.