Radiator Pressure Flush and Coolant Change

sb mm 20.03.001

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

Warning: Drain the coolant only when the coolant and engine are cool. Draining it when these are hot could cause severe personal injury due to scalding.

  1. Drain the radiator.
    1. Remove the surge tank cap.
    2. Remove the plug from the bottom of the radiator on the left side of the tank to drain the engine coolant. See Fig..

      Note: Front radiator shown; other models will be similar.

      1. Bumper

      2. Radiator Drain Plug

      3. Engine

      Fig. 1, Radiator Drain Plug

  2. Disconnect the radiator inlet and outlet hose connections.
  3. Flush the radiator.
    1. Attach a flushing gun nozzle to the radiator outlet.
    2. Run water in until the radiator is full
    3. Apply no more than 20 psi (138 kPa) air pressure intermittently to help dislodge sediment buildup in the core.

      Caution: When flushing the radiator, do not apply more than 20 psi (138 kPa) air pressure. Excessive pressure can damage the radiator or heater core.
    4. Drain the radiator. Then, flush the radiator until clean water flows from it. Remove the flushing gun.
    5. Install the plug in the bottom of the radiator.
    6. Connect the hoses. When you install 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. See Fig.. Use a torque wrench to install these hose clamps. The correct installation torque for Breeze Constant-Torque hose clamps is as follows:
      For hose clamps with a 5/16-inch tightening screw hex: 40 lbf·in (460 N·cm).
      For hose clamps with a 3/8-inch tightening screw hex: 90 lbf·in (1020 N·cm).

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

      • The belleville washer stacks must be collapsed almost flat.

      1. Tightening Screw Hex

      Fig. 2, Breeze Constant-Torque Hose Clamp

      7. Important: 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.

      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.

    7. Fill the cooling system.
      1. Slowly add a 50/50 mixture of antifreeze and water to the surge tank, no more than 3.0 gallons per minute (gpm). Fill to the top of the surge tank. For approved coolants, refer to the coolant label on the vehicle or the engine manufacturer's service literature. Coolant used must be compatible with the engine manufacturer’s coolant specifications. For Cummins engine service literature, refer to the Cummins Online website at https://www.cummins.com/support/manuals or scan the QR code. See Fig.. For Detroit™ engine service literature, refer to the Detroit Diesel link on the DTNA TechLit website https://www.dtnatechlit.com/portal-public or scan the QR code. See Fig..

        Fig. 3, Cummins QR Code

        Fig. 4, TechLit QR Code

      2. With the radiator cap removed, start the engine and run it at low idle for 1 minute; then at high idle for 1 minute. Return to low idle for 1 minute.
      3. Turn the engine off. Fill the surge tank to the COLD MAX line. Install the radiator cap.
    Note:
    Parent topic: Engine Cooling/Radiator
    Document Number: 0000120256
    Manual Publication Date: 2025-01-08
    Topic Publication Date: 2024-11-18