Coolant Surge Tank Pressure Cap; Engine Overheating - Hummer H2 2004 Owner's Manual

Adding Coolant
If you need more coolant, add the proper DEX-COOL
coolant mixture at the surge tank, but only when the
engine is cool.
CAUTION:
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You can be burned if you spill coolant on hot
engine parts. Coolant contains ethylene glycol,
and it will burn if the engine parts are hot
enough. Do not spill coolant on a hot engine.
When replacing the pressure cap, make sure it
is hand-tight.

Coolant Surge Tank Pressure Cap

The coolant surge tank pressure cap must be fully
installed on the coolant surge tank. See Engine
Compartment Overview on page 5-12 for more
information on location.
Notice: If the pressure cap is not tightly
installed, coolant loss and possible engine
damage may occur. Be sure the cap is properly
and tightly secured.

Engine Overheating

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You will find a coolant temperature gage on your
vehicle's instrument panel. See Engine Coolant
Temperature Gage on page 3-35. In addition, you will
find an ENGINE COOLANT HOT, ENGINE
OVERHEATED and a REDUCED ENGINE POWER
message in the DIC on the instrument panel. See DIC
Warnings and Messages on page 3-54.
Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and the
REDUCED ENGINE POWER message is displayed,
an overheat protection mode which alternates firing
groups of cylinders helps prevent engine damage. In this
mode, you will notice a loss in power and engine
performance. This operating mode allows your vehicle
to be driven to a safe place in an emergency. Driving
extended miles (km) and/or towing a trailer in the
overheat protection mode should be avoided.
Notice: After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any
repair. The engine oil will be severely degraded.
Repair the cause of coolant loss, change the oil
and reset the oil life system. See Engine Oil
on page 5-14.
5-27