How to Add Coolant to the Coolant Surge Tank for Gasoline Engines

If the vehicle has a diesel engine, see “Cooling System” in the Duramax Diesel Supplement for the proper coolant fill procedure.

WARNING
You can be burned if you spill coolant on hot engine parts.

Coolant contains ethylene glycol and it will burn if the engine parts are hot enough. Do not spill coolant on a hot engine.

Notice: This vehicle has a specific coolant fill procedure.

Failure to follow this procedure could cause the engine to overheat and be severely damaged.

WARNING
An electric engine cooling fan under the hood can start up even when the engine is not running and can cause injury. Keep hands, clothing, and tools away from any underhood electric fan.

WARNING
Steam and scalding liquids from a hot cooling system can blow out and burn you badly. They are under pressure, and if you turn the coolant surge tank pressure cap—even a little—they can come out at high speed. Never turn the cap when the cooling system, including the coolant surge tank pressure cap, is hot.

Wait for the cooling system and coolant surge tank pressure cap to cool if you ever have to turn the pressure cap.

If no coolant is visible in the surge tank, add coolant as follows:

1. Remove the coolant surge tank pressure cap when the cooling system, including the coolant surge tank pressure cap and upper radiator hose, is no longer hot.

1. Remove the coolant surge tank pressure cap when the cooling system, including the coolant surge tank pressure cap and upper radiator hose, is no longer hot.

Turn the pressure cap slowly counterclockwise about one full turn. If a hiss is heard, wait for that to stop. A hiss means there is still some pressure left.

2. Keep turning the pressure cap slowly, and remove it.

3. Fill the coolant surge tank with the proper mixture to the FULL COLD mark.

3. Fill the coolant surge tank with the proper mixture to the FULL COLD mark.

4. With the coolant surge tank pressure cap off, start the engine and let it run until the engine coolant temperature gauge indicates approximately 90°C (195°F).

By this time, the coolant level inside the coolant surge tank may be lower. If the level is lower, add more of the proper mixture to the coolant surge tank until the level reaches the FULL COLD mark.

5. Replace the pressure cap. Be sure the pressure cap is hand-tight and fully seated.

6. Verify coolant level after the engine is shut off and the coolant is cold. If necessary, repeat coolant fill procedure Steps 1 through 6.

Notice: If the pressure cap is not tightly installed, coolant loss and possible engine damage may occur. Be sure the cap is properly and tightly secured.

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