Global Machinery Company Sierra 1999 - Manual (Page 272)

yellow blue
5-12
Cooling System (Gasoline Engine)
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.
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.