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: 1834921  Size: B3
  1. Engine Coolant Reservoir

  2. Radiator Pressure Cap (covered)

  3. Engine Cooling Fans

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 the coolant inside the coolant recovery tank is boiling, do not do anything else until it cools down. The vehicle should be parked on a level surface.

When the engine is cold, the coolant level should be at least up to the FULL COLD mark. 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 fans are running. If the engine is overheating, both fans should be running. If they are not, your vehicle needs service.

Notice: Engine damage from running the engine without coolant is not covered by the warranty.

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 Recovery Tank

Notice: This vehicle has a specific coolant fill procedure. Failure to follow this procedure could cause the engine to overheat and be severely damaged.

If you have not found a problem yet, check to see if coolant is visible in the coolant recovery tank. 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 recovery tank, but be sure the cooling system, including the coolant recovery tank pressure cap, is cool before you do it. See Engine Coolant for more information.

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.

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.

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.

When the coolant in the coolant recovery tank is at the FULL COLD mark, start your vehicle. If the overheat warning continues, there is one more thing you can try. You can add the proper mixture directly to the radiator, but be sure the cooling system is cool before you do it.


    Object Number: 1837325  Size: B2
  1. To remove the panel that covers the radiator cap, detach fasteners and lift off panel.
  2. Remove the radiator pressure cap when the cooling system, including the upper radiator hose, is no longer hot. Turn the pressure cap slowly counterclockwise about one full turn. If you hear a hiss, wait for that to stop. A hiss means there is still some pressure left.

  3. Object Number: 809006  Size: A2
  4. Keep turning the pressure cap slowly, and remove it.
  5. 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.

  6. Object Number: 1852176  Size: B3
  7. Fill the coolant recovery tank to the FULL COLD mark.
  8. Reinstall the cap on the coolant recovery tank, but leave the radiator pressure cap off.

  9. Object Number: 1834923  Size: B3
  10. Start the engine and let it run until you can feel the upper radiator hose getting hot. Watch out for the engine cooling fan.
  11. By this time, the coolant level inside the radiator filler 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. Replace the pressure cap.

At any time during this procedure if coolant begins to flow out of the filler neck, reinstall the pressure cap. Be sure to secure it tightly.