GMC 2000 Sierra - Manual (Page 279)

yellow blue
5-12
Cooling System
When you decide it’s safe to lift the hood, here’s what
you’ll see:
A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine Fan
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.