GMC T-Series 2007 Owner's Manual page 222

When the engine is cold, the coolant level
should be at the COLD FULL mark. 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.
CAUTION:
{
Heater and radiator hoses, and other
engine parts, can be very hot. Do not
touch them. If you do, you can be burned.
Do not run the engine if there is a leak.
If you run the engine, it could lose all
coolant. That could cause an engine fire,
and you could be burned. Get any leak
fixed before you drive the vehicle.
If there seems to be no leak, start the engine
again. The engine cooling fan speed should
increase when idle speed is doubled by pushing
the accelerator pedal down. If it does not,
your vehicle needs service. Turn off the engine.
222
Notice: Using coolant other than DEX-COOL
may cause premature engine, heater core,
or radiator corrosion. In addition, the engine
coolant could require changing sooner,
at 30,000 miles (50 000 km) or 24 months,
whichever occurs first. Any repairs would
not be covered by your warranty. Always use
®
DEX-COOL (silicate-free) coolant in your
vehicle.
How to Add Coolant to the Coolant
Surge Tank
If you have not found a problem yet, but the
coolant level is not at the COLD FULL mark,
add a 50/50 mixture of clean, drinkable water and
®
DEX-COOL coolant at the coolant surge tank, but
be sure the cooling system, including the coolant
surge tank pressure cap, is cool before you do it.
See Engine Coolant on page 216 for more
information.
®