How to Add Coolant to the Coolant Surge Tank
If the vehicle has a diesel engine, see “Cooling System” in the Duramax diesel supplement for the proper coolant fill procedure.
Warning: Spilling coolant on hot engine parts can burn you. Coolant contains ethylene glycol and it will burn if the engine parts are hot enough.
Warning: Plain water or other liquids such as alcohol can boil before the proper coolant mixture will. With plain water or the wrong mixture, the engine could overheat and catch fire.
Warning: Steam and scalding liquids from a hot cooling system are under pressure. Never turn the pressure cap when hot; wait for it to cool.
Caution: Failure to follow the specific coolant fill procedure could cause engine overheating or system damage.
Coolant Fill Procedure
- Remove the coolant surge tank pressure cap when the cooling system is cool. Turn slowly counterclockwise about one full turn. If hissing occurs, wait for it to stop.
- Continue turning and remove the cap.
- Fill the coolant surge tank with the proper mixture to the full cold mark.
- With cap off, start the engine and let it run until coolant temperature reaches ~90 °C (195 °F). If level drops, add more coolant to reach the mark.
- Replace the pressure cap tightly.
- Verify coolant level after engine is off and cold. Repeat steps 1–6 if necessary.
Caution: Ensure the pressure cap is tightly installed. Otherwise, coolant loss and engine damage may occur.
Engine Overheating
Caution: Do not run the engine if there is a leak in the cooling system; it can cause coolant loss and damage.
The vehicle has a coolant temperature gauge and warning light. Messages include ENGINE OVERHEATED STOP ENGINE, ENGINE OVERHEATED IDLE ENGINE, and ENGINE POWER IS REDUCED.
If you choose to lift the hood, park on level ground, check cooling fans, and follow safe procedures.
If Steam is Coming from the Engine Compartment
Warning: Steam and scalding liquids from a hot cooling system are under pressure. Never remove cap when hot.
If
