GMC Sierra Owners Manual
Engine CoolantVehicle Care / Vehicle Checks / Engine Coolant
The cooling system in the vehicle is filled with DEX-COOL® engine coolant. This coolant is designed to remain in the vehicle for 5 years or 240 000 km (150,000 mi), whichever occurs first.
The following explains the cooling system and how to check and add coolant when it is low. If there is a problem with engine overheating, see Engine Overheating on page 10‑23.
What to Use
WARNING
Adding only plain water or some other liquid to the cooling system can be dangerous. Plain water and other liquids, can boil before the proper coolant mixture will.
The coolant warning system is set for the proper coolant mixture.
With plain water or the wrong mixture, the engine could get too hot but you would not get the overheat warning. The engine could catch fire and you or others could be burned. Use a 50/50 mixture of clean, drinkable water and DEX-COOL coolant.
Use a 50/50 mixture of clean, drinkable water and DEX-COOL coolant. If using this mixture, nothing else needs to be added.
This mixture:
• Gives freezing protection down to −37°C (−34°F), outside temperature
• Gives boiling protection up to 129°C (265°F), engine temperature
• Protects against rust and corrosion
• Will not damage aluminum parts
• Helps keep the proper engine temperature
Notice: If an improper coolant mixture is used, the engine could overheat and be badly damaged.
The repair cost would not be covered by the vehicle warranty.
Too much water in the mixture can freeze and crack the engine, radiator, heater core, and other parts.
Notice: If extra inhibitors and/or additives are used in the vehicle cooling system, the vehicle could be damaged. Use only the proper mixture of the engine coolant listed in this manual for the cooling system. See Recommended Fluids and Lubricants on page 11‑12 for more information.
Never dispose of engine coolant by putting it in the trash, pouring it on the ground, or into sewers, streams, or bodies of water. Have the coolant changed by an authorized service center, familiar with legal requirements regarding used coolant disposal. This will help protect the environment and your health.
Checking Coolant
The coolant surge tank is located in the engine compartment on the passenger side of the vehicle. See Engine Compartment Overview on page 10‑6 for more information on location.
The vehicle must be on a level surface when checking the coolant level.
Check to see if coolant is visible in the coolant surge tank. If the coolant inside the coolant surge tank is boiling, do not do anything else until it cools down. If coolant is visible but the coolant level is not at or above the FULL COLD mark, add a 50/50 mixture of clean, drinkable water and DEX-COOL coolant at the coolant surge tank, but be sure the cooling system is cool before this is done.
The coolant level should be at or above the FULL COLD mark. If it is not, there may be a leak in the cooling system.
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.
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.
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.
