2001 GMC Sierra 1500 Pickup Owner's Manual - Page 318

If the coolant inside the coolant surge tank is boiling, don't do anything else until it cools down. When the engine is cold, the coolant level should be at or above the FILL COLD mark. If it isn't, you may have a leak 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. Don't touch them. If you do, you can be burned. Don't 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. NOTICE: Engine damage from running your engine without coolant isn't covered by your warranty. See "Overheated Engine Protection Operating Mode" in the Index. 5-12