Chevrolet 2009 Cobalt Owner's Manual page 288

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.
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 surge tank
pressure cap — even a little — they can come out
at high speed. Never turn the cap when the
cooling system, including the surge tank pressure
cap, is hot. Wait for the cooling system and surge
tank pressure cap to cool if you ever have to turn
the pressure cap.
5-30
If coolant is needed, add the proper DEX-COOL
coolant mixture at the coolant surge tank.
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. If you hear a hiss, wait for
that to stop. This will allow any pressure still left
to be vented out the discharge hose.
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2. Then keep turning the
pressure cap slowly,
and remove it.