Cadillac 2008 STS, Owner'S Manual, Page: 350 / 500

Cooling System
When you decide it is safe to lift the hood, this is what
you will see:
A. Engine Cooling Fans
B. Coolant Surge Tank and Pressure Cap
Some vehicles may have an engine driven fan, as well
as the electric pusher fans which are located behind
the vehicle’s grille.
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CAUTION:
An electric engine cooling fan under the hood
can start up even when the engine is not
running and can injure you. 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.
When the engine is cold, the coolant level should be at
or slightly above the FULL COLD/FROID line on the
side of the coolant surge tank. 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.
3.6L V6 Engine shown, 4.6L V8 and 4.4L V8 STS-V
Engines similar
5-32