GM Service Manual Online
For 1990-2009 cars only

When you decide it is safe to lift the hood, here is what you will see:


Object Number: 1504967  Size: B3
  1. Radiator Pressure Cap (Out of View)

  2. Electric Engine Cooling Fan

  3. Engine Coolant Overflow Reservoir

Caution: 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.

If you can hear the coolant inside the coolant overflow reservoir bubbling or boiling, do not do anything else until it cools down. The vehicle should be parked on a level surface.

The coolant level should be at or above the bottom arrow on the dipstick. If it is not, you may have a leak at the pressure cap or in the radiator hoses, heater hoses, radiator, water pump, or somewhere else in the cooling system.

Caution: Heater and radiator hoses, and other engine parts, can be very hot. Do not touch them. If you do, you can be burned.

Do not run the engine if there is a leak. If you run the engine, it could lose all coolant. That could cause an engine fire, and you could be burned. Get any leak fixed before you drive the vehicle.

If there seems to be no leak, with the engine on, check to see if the electric engine cooling fan is running. If the engine is overheating, the fan should be running. If it is not, your vehicle needs service.

Notice: If you operate the engine without coolant or fail to maintain the cooling system properly, you could damage the engine. The repairs would not be covered by your warranty. Always follow the maintenance schedule in this manual for maintaining your cooling system. See Cooling System for more information.

Notice: Using coolant other than DEX-COOL® can cause premature engine, heater core, or radiator corrosion. In addition, the engine coolant could require changing sooner, at 30,000 miles (50 000 km) or 24 months, whichever occurs first. Any repairs would not be covered by the vehicle warranty. Always use DEX-COOL® (silicate-free) coolant in the vehicle.

How to Add Coolant to the Coolant Overflow Reservoir

Caution: Adding only plain water to the cooling system can be dangerous. Plain water, or some other liquid such as alcohol, can boil before the proper coolant mixture will. The vehicle's 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.

If you have not found a problem yet, check the coolant level on the coolant overflow reservoir dipstick. If the coolant level is not at or above the bottom arrow on the dipstick, add a 50/50 mixture of clean, drinkable water and DEX-COOL® coolant at the coolant overflow reservoir. See Engine Coolant for more information.

Notice: In cold weather, water can freeze and crack the engine, radiator, heater core and other parts. Use the recommended coolant and the proper coolant mixture.

Caution: 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.

To add coolant to the overflow reservoir, do the following:

  1. Remove the coolant overflow reservoir cap when the cooling system is no longer hot.

  2. Object Number: 1504984  Size: B3
  3. Fill the coolant overflow reservoir with the proper mixture, until it reaches the bottom arrow on the dipstick.
  4. Replace the dipstick, then press down on the coolant reservoir cap while turning it clockwise until it stops, to lock it into position.

If there is still no coolant visible on the dipstick, there is one more thing you can try. You can add the proper coolant mixture directly to the radiator, but be sure the system is cool before you do it.

Caution: 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 surge tank pressure cap -- even a little -- they can come out at high speed. Never turn the cap when the cooling system, including the surge tank pressure cap, is hot. Wait for the cooling system and surge tank pressure cap to cool if you ever have to turn the pressure cap.

How to Add Coolant to the Radiator

Notice: Your engine has a specific radiator fill procedure. Failure to follow this procedure could cause your engine to overheat and be severely damaged.

  1. You can remove the radiator pressure cap when the cooling system, including the radiator pressure cap and upper radiator hose, is no longer hot. See Engine Compartment Overview for more information on the location of the radiator pressure cap.
  2. Remove the cap cover. Turn the pressure cap slowly counterclockwise until it first stops. Do not press down while turning the pressure cap. If you hear a hiss, wait for that to stop. A hiss means there is still some pressure left.

  3. Then keep turning the pressure cap, but now push down as you turn it. Remove the pressure cap.
  4. Fill the radiator with the proper DEX-COOL® coolant mixture, up to the base of the filler neck. See Engine Coolant for more information about the proper coolant mixture.
  5. Rinse or wipe any spilled coolant from the engine and the compartment.
  6. Then fill the coolant overflow reservoir to the bottom arrow on the dipstick.
  7. Put the cap back on the coolant overflow reservoir, but leave the radiator pressure cap off.
  8. Start the engine and let it run until you can feel the upper radiator hose getting hot. Watch out for the engine cooling fan.
  9. By this time, the coolant level inside the radiator fill neck may be lower. If the level is lower, add more of the proper DEX-COOL® coolant mixture through the filler neck until the level reaches the base of the filler neck.
  10. Then replace the radiator pressure cap. At any time during this procedure, if coolant begins to flow out of the filler neck, reinstall the pressure cap. Be sure the pressure cap is hand-tight and fully seated. Replace the cap cover.
  11. Check the coolant in the overflow reservoir. The level should be at the bottom arrow on the dipstick when the engine is cold.
  12. See your dealer, if necessary.