Radiator Pressure-Flushing and Coolant Change

cen mm 20.02.000

Note: For additional instructions on cleaning and flushing the engine's cooling system, see the applicable engine manufacturer's maintenance and operation manual.

  1. Park the vehicle, apply the parking brakes. Tilt the hood or cab. For instructions on tilting the cab, see of the Century Class Trucks Workshop Manual.
  2. Place a suitable container under the elbow of the radiator outlet pipe and under the radiator. The container should hold at least 60 quarts (58.6 liters) of fluid for single radiator applications, or 80 quarts (76 liters) for Argosy's with auxiliary radiators.

    3. Warning: Do not remove or loosen the surge tank cap until the engine and cooling system have completely cooled. Use extreme care when removing the cap. A sudden release of pressure from removing the cap prior to the system cooling can result in a surge of scalding coolant that could cause serious personal injury.

  3. Remove the surge tank cap.
  4. On Argosy's with auxiliary radiators, open the remote bleed valve. See Fig..

    Note: The main radiator drain plug is not shown.

    1. Surge Tank

    2. Remote Bleed Valve

    3. Main Radiator

    4. Auxiliary Radiator

    5. Auxiliary Radiator Temperature Sensor

    6. Fan Power Harness

    7. Auxiliary Radiator Drain Plug

    8. Cold Coolant Hose

    9. Hot Coolant Hose

    Fig. 1, Coolant System, Argosy, with Auxiliary Radiator

    5. Warning: Do not attempt to drain the cooling system until the coolant and engine are cool. Draining the cooling system prior to the system cooling could cause severe personal injury due to scalding.

  5. Remove the drain plugs from the radiator side tank, the lower tank on auxiliary radiators, and at the lower radiator outlet pipe elbow, if equipped. See Fig.. Allow the coolant to drain.

    Note: Cummins M11 engine shown.

    1. Coolant Drain Plug

    Fig. 2, Coolant Drain Plug Location

  6. Install and tighten the drain plug(s) and the radiator outlet pipe drain plug after the radiator has been drained. Do not overtighten the plugs.
  7. Flush the radiator(s) as follows.
    1. Disconnect the radiator upper and lower hoses.
    2. Attach the flushing gun nozzle to the radiator at the lower radiator hose opening. Run the water until the radiator is full.

      Notice: When flushing the radiator, do not apply more than 15 psi (100 kPa) air pressure. Excessive pressure can damage the radiator.
      1. Gradually, apply air pressure to help dislodge sediment built up in the radiator core. Do not apply more than 15 psi (103 kPa) air pressure to the radiator. Pressures exceeding 15 psi (103 kPa) could damage the radiator core.
      2. Shut off the air at the pressure gun nozzle and allow the radiator to refill with water.
      3. Repeat the previous two steps until clean water flows from the radiator.
      4. Remove the radiator side tank drain plug and allow the radiator to drain.
    3. Connect the hoses. The hose clamps on the main radiator can be either T-bolt clamps (see Fig.) or Breeze Constant-Torque clamps (see Fig.).
      When working with T-bolt hose clamps, tighten the clamps 55 lbf·in (620 N·cm). These clamps are now standard on hoses with an inside diameter greater than 2 inches (51 mm).
      When installing Breeze Constant-Torque hose clamps, the clamps must be tightened to the correct torque. The screw tip of the clamp must extend about 1/4 inch (6 mm) from the clamp housing, and the Belleville washer stacks must be collapsed almost flat. Use a torque wrench to install these hose clamps correctly. The correct installation torque is as follows:
      For Breeze Constant-Torque clamps with a 5/16-inch tightening screw hex: 55 lbf·in (620 N·cm).
      For Breeze Constant-Torque clamps with a 3/8-inch tightening screw hex: 90 lbf·in (1020 N·cm).

      Fig. 3, T-Bolt Type Hose Clamp

      • The screw tip must extend about 1/4 inch (6 mm).

      • Belleville washer stacks must be collapsed almost flat.

      1. Tightening Screw Hex

      Fig. 4, Breeze Constant-Torque Hose Clamp Installation

      4. Note: All hose clamps will lose torque after installation due to "compression set." However, when correctly installed, Breeze Constant-Torque clamps will hold enough torque to automatically adjust and keep consistent sealing pressure. During vehicle operation and shutdown, the screw tip may adjust according to temperature and pressure changes. The torque may need to be adjusted for individual applications.

    4. Place a pan under the coolant filter to catch engine coolant.
    5. Remove the coolant filter with a strap or chain wrench. Install a new coolant filter and tighten.

      6. Important: On vehicles with EPA07 compliant engines, the coolant capacity varies depending on the engine and accessory installation. After servicing the cooling system, always verify that the coolant level is between the MIN and MAX lines on the surge tank.

    6. Fill the cooling system with new coolant. Refer to the engine manufacturer's service literature for specific coolant information.
    7. On single radiator applications, add coolant as follows.
      1. Fill the cooling system at the surge tank.
      2. Install the surge tank cap.
      3. Return the hood or cab to the operating position. See of the Century Class Trucks Workshop Manual for cab tilt instructions.
      4. Start the engine and turn on the cab heater. Allow the engine to warm up to normal operating temperature. Check the radiator and hoses for leaks. Repair if necessary.
      5. Shut off the engine, then check the coolant level in the surge tank. Add coolant if the level is not between the MIN and MAX lines on the surge tank.
    8. On Argosy's with auxiliary radiators, bleed the system while adding coolant as follows.
      1. Open the remote bleed valve on the left side of the frontwall.
      2. Fill the cooling system at the surge tank; continue adding coolant until a non-aerated coolant stream comes out of the remote bleed valve. This allows air to be expelled from the auxiliary system.
      3. Close the remote bleed valve.
      4. Continue filling until the coolant reaches the high level mark on the surge tank.
      5. Run the engine for 5 minutes to allow the system to de-aerate.
      6. Check the coolant level again; add coolant to the high level mark.
    Note:
    Parent topic: Engine Cooling/Radiator
    Document Number: 0000121903
    Manual Publication Date: 2025-02-11
    Topic Publication Date: 2024-06-04