Cleaning/Flushing the Cooling System

Cleaning/Flushing the Cooling System - Ops

Collect the used coolant, cleaning solutions, and washing liquids and dispose of them in an environmentally responsible manner.

Degrease as follows:

Warning: HOT COOLANT

To avoid scalding from the expulsion of hot coolant, never remove the cooling system pressure cap while the engine is at operating temperature. Wear adequate protective clothing (face shield, rubber gloves, apron, and boots). Remove the cap slowly to relieve pressure.

  1. First remove debris (such as dust, insects) from the fins of the radiator grille.

    2. Warning: EYE INJURY

    To avoid injury from flying debris when using compressed air, wear adequate eye protection (face shield or safety goggles) and do not exceed 276 kPa (40 psi) air pressure.

    Notice: Clean at moderate air pressures only to avoid damaging the radiator grille fins.
  2. Remove the debris by blowing them through with compressed air or spraying them out with water. Work from the rear of the radiator (in the opposite direction of the normal cooling air flow).
  3. Drain the coolant when the engine is cold. Cooling System Drain Procedure. For detailed procedures, see the vehicle/chassis maintenance manual. For types of coolant,Coolant Selections and Maintenance for the listing of required intervals using the recommended coolants.
  4. If the HVAC unit is connected to the cooling system, open the regulating valves all the way.
  5. Fill the cooling system with a 5% solution (1.6 ounces per quart [50 grams per liter] of water) of a mildly alkaline cleaning agent. Coolant Selections and Maintenance.
  6. Run the engine at moderate speed until the thermostat starts to open. The thermostat starts to open at 88°C (190°F) and is fully open at 95°C (203°F). Then run it for about five minutes longer. Shut down the engine and allow it to cool to approximately 50°C (112°F).
  7. Drain all the cleaning solution.
  8. Flush the cleaning solution from the cooling system.
    1. Immediately after draining the cleaning solution, flush the system with clean water.
    2. Once the clean water has drained, fill the system again with clean water.
    3. Run the engine at moderate speed until the thermostat starts to open. The thermostat starts to open at 88°C (190°F) and is fully open at 95°C (203°F). Then run it for about five minutes longer. Shut down the engine and allow it to cool to approximately 50°C (112°F).
    4. Drain the hot water.
  9. Fill the cooling system with new coolant. For detailed procedures, see the vehicle/chassis maintenance manual. For types of coolant,Coolant Selections and Maintenance for the listing of required intervals using the recommended coolants.
Note:
Parent topic: How to Procedures
Document Number: 0000022458
Manual Publication Date: 2024-01-05
Topic Publication Date: 2023-12-10