Pontiac G3 2009 Owner's Manual page 229

The engine coolant surge tank is located in the rear
of the engine compartment on the driver side of
the vehicle. See Engine Compartment Overview
on page 5-12 for more information on location.
{
CAUTION:
Turning the surge tank pressure cap when the
engine and radiator are hot can allow steam and
scalding liquids to blow out and burn you badly.
Never turn the surge tank pressure cap — even
a little — when the engine and radiator are hot.
When the engine is cold, the coolant level should
be between the Maximum (A) and Minimum (B) marks
on the coolant surge tank. The level rises at engine
operation temperature and drops again when the
engine cools down.
The coolant should be between the Maximum (A) and
Minimum (B) marks, when the engine is cold. If it is not,
there could be a leak in the cooling system.
5-25