Replacement of the Coolant
At the intervals specified in the maintenance schedule, or whenever the coolant becomes dirty, flush and refill the cooling system.
Note: The coolant replacement interval is increased to 100,000 miles (161 000 km) or 60 months, whichever comes first. For this interval to apply, you must check and, if necessary, recharge the supplemental coolant additive (SCA) levels and the freeze point every 25,000 miles (40 000 km) or 6 months, whichever comes first. For Cummins engine service literature, refer to the Cummins Online website, see 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, see https://www.dtnatechlit.com/portal-public or scan the QR code. See Fig..
Fig. 1, Cummins QR Code
Fig. 2, TechLit QR Code
- Drain the cooling system, as follows.
- When the engine is cool, remove the radiator cap.Turn the cap slowly counterclockwise until it reaches a 'stop.' Do not press down while turning the cap. Wait until any remaining pressure (indicated by a hissing sound) is relieved, then press down on the cap and continue turning it counterclockwise.
- When the cap is removed, run the engine until the upper
radiator hose is hot—this shows that the thermostat is open
and the coolant is flowing through the system.
Warning: Use extreme care when draining coolant that is very warm. It may still be hot enough to cause serious personal injury by scalding.
- Stop the engine. Remove the lower radiator hose to drain the coolant. Drainage may be speeded by removing the plug in the bottom of the water inlet.
- When the engine is cool, remove the radiator cap.
- Flush the cooling system, as follows.
Notice: During filling, air must be vented from the engine coolant passages. Any air trapped in the system can cause severe engine damage.
- Connect the lower radiator hose and install the plug in the bottom of the water inlet.
- Open the engine venting petcock.
- Add water to the surge tank until the system is filled.
- Start the engine. Run it at low idle for 10 seconds, then at high idle for 1 minute. Return to low idle.
- Close the lower petcock when a steady stream of water is flowing from it. Don't let more than 1.5 quarts (1.4 L) of water escape.
- Close the upper petcock when a steady stream of water is flowing from it. Don't let more than 1.5 quarts (1.4 L) of water escape.
- Repeat several times until the drained liquid is nearly colorless.
- Completely drain the system, then close the radiator and block the drain valves.
- Disconnect all hoses from the surge tank. Remove the tank and pour out any fluid. Scrub and clean the inside of the surge tank with soap and water. Flush it with clean water, then drain it. Install the surge tank and hoses.
- Fill the cooling system.
- 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.
- 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.
- Turn the engine off. Fill the surge tank to the COLD MAX line. Install the radiator cap.
Warning: Do not remove or loosen the radiator 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.
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.