GM Service Manual Online
For 1990-2009 cars only

The engine coolant surge tank is located in the rear of the engine compartment. See Engine Compartment Overview for more information on location.

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 surge tank is boiling, do not do anything else until it cools down. The vehicle should be parked on a level surface. Make sure that the air conditioning is turned off.

The coolant level should be between the MIN and MAX marks on the coolant surge tank when the engine is cool. 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: Engine damage from running the engine without coolant is not covered by the warranty.

How to Add Coolant to the Coolant Surge 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 surge tank. If coolant is visible but the coolant level is not between the MIN and MAX marks, add a 50/50 mixture of clean, drinkable water and proper coolant at the coolant surge tank, but be sure the cooling system, including the coolant surge tank pressure cap, is cool before you do it. See Engine Coolant for more information.

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

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 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.

Caution: Adding only plain water to your cooling system can be dangerous. Plain water, or some other liquid such as alcohol, can boil before the proper coolant mixture will. Your vehicle's coolant warning system is set for the proper coolant mixture. With plain water or the wrong mixture, your engine could get too hot but you would not get the overheat warning. Your engine could catch fire and you or others could be burned. Use a 50/50 mixture of clean, drinkable water and a proper 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.

  1. You can 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 two or two and one-half turns.
  2. If you hear a hiss, wait for that to stop. This will allow any pressure still left to be vented out the discharge hose.


    Object Number: 1325878  Size: A3
  3. Then keep turning the pressure cap slowly, and remove it.

  4. Object Number: 1325880  Size: B3
  5. Fill the coolant surge tank with the proper mixture to the MAX mark on the coolant surge tank. Wait about five minutes, then check to see if the level is below the MAX mark. If the level is below the MIN mark, add additional coolant to bring the level up to the MAX mark. Repeat this procedure until the level remains constant at the MAX mark for at least five minutes.
  6. With the coolant surge tank pressure cap off, start the engine and let it run until you can feel the upper radiator hose getting hot. Watch out for the engine cooling fan.
  7. By this time, the coolant level inside the coolant surge tank may be lower. If the level is lower than the MAX mark, add more of the proper mixture to the coolant surge tank until the level reaches the MAX mark.

  8. Then replace the pressure cap. Be sure the pressure cap is hand-tight and fully seated.
  9. See your dealer, if necessary.