2007 HUMMER H2 engine overheat

Coolant Surge Tank Pressure Cap
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.
The coolant surge tank pressure cap must be fully
installed on the coolant surge tank. SeeEngine
Compartment Overview on page 402for more
information on location.
Engine Overheating
You will nd a coolant temperature gage on your
vehicle’s instrument panel. SeeEngine Coolant
Temperature Gage on page 213.
In addition, you will nd an ENGINE COOLANT
HOT, ENGINE OVERHEATED and a REDUCED
ENGINE POWER message in the Driver
Information Center (DIC) on the instrument panel.
SeeDIC Warnings and Messages on page 226.
If Steam Is Coming From Your Engine
{CAUTION:
Steam from an overheated engine can burn
you badly, even if you just open the hood.
Stay away from the engine if you see or
hear steam coming from it. Turn it off and
get everyone away from the vehicle until
it cools down. Wait until there is no sign of
steam or coolant before you open the hood.
If you keep driving when the vehicles
engine is overheated, the liquids in it can
catch re. You or others could be badly
burned. Stop your engine if it overheats,
and get out of the vehicle until the engine
is cool.
SeeOverheated Engine Protection
Operating Mode on page 420for
information on driving to a safe place in
an emergency.
418

Notice:If your engine catches re because
you keep driving with no coolant, your vehicle
can be badly damaged. The costly repairs
would not be covered by your warranty.
SeeOverheated Engine Protection Operating
Mode on page 420for information on driving to
a safe place in an emergency.
If No Steam Is Coming From Your
Engine
The ENGINE COOLANT HOT message, along
with a low coolant condition, can indicate a serious
problem.
If you get an engine overheat warning, but see or
hear no steam, the problem may not be too
serious. Sometimes the engine can get a little
too hot when you:
Climb a long hill on a hot day.
Stop after high-speed driving.
Idle for long periods in traffic.
Tow a trailer. SeeTowing a Trailer on
page 374.If you get the ENGINE COOLANT HOT message
with no sign of steam, try this for a minute or so:
1. Turn on your heater to full hot at the highest fan
speed and open the windows as necessary.
2. If you are in a traffic jam, shift to
NEUTRAL (N); otherwise, shift to the highest
gear while driving — DRIVE (D).
If you no longer have the overheat warning,
you can drive. Just to be safe, drive slower for
about 10 minutes. If the warning does not
come back on, you can drive normally.
If the warning continues and you have not
stopped, pull over, stop, and park your vehicle
right away.
If there is still no sign of steam, push down the
accelerator until the engine speed is about
twice as fast as normal idle speed for at least
three minutes while you are parked. If you
still have the warning, turn off the engine and get
everyone out of the vehicle until it cools down.
Also, see “Overheated Engine Protection
Operating Mode” later in this section.
You may decide not to lift the hood but to get
service help right away.
419

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 ring 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. SeeEngine Oil on page 404.
Cooling System
When you decide it is safe to lift the hood, here is
what you will see:
A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine Cooling 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.
420

Check the coolant level after the system cools
down. Some amount of coolant may be lost due to
overheating.
The coolant level should be at or above the FULL
COLD 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 re,
and you could be burned. Get any leak
xed 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.
Notice:Engine damage from running your
engine without coolant is not covered by your
warranty. SeeOverheated Engine Protection
Operating Mode on page 420for information on
driving to a safe place in an emergency.
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 rst. Any repairs would not
be covered by your warranty. Always use
DEX-COOL
®(silicate-free) coolant in your
vehicle.
421

How to Add Coolant to the Coolant
Surge Tank
If you have not found a problem yet, check to see
if coolant is visible in the surge tank. If coolant
is visible but the coolant level is not at or above
the FULL COLD 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. SeeEngine
Coolant on page 415for more information.
If no coolant is visible in the surge tank, add
coolant as follows:
{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 radiator pressure cap — even a
little — they can come out at high speed.
CAUTION: (Continued)
CAUTION: (Continued)
Never turn the cap when the cooling
system, including the radiator pressure
cap, is hot. Wait for the cooling system
and radiator pressure cap to cool if you
ever have to turn the pressure cap.
{CAUTION:
Adding only plain water to your cooling
system can be dangerous. Plain water, or
some other liquid such as alcohol, can
boil before the proper coolant mixture will.
Your vehicle’s coolant warning system is
set for the proper coolant mixture. With
plain water or the wrong mixture, your
engine could get too hot but you would
not get the overheat warning. Your engine
could catch re and you or others could
be burned. Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
®coolant.
422

Electrical System (cont.)
Underhood Fuse Block............................. 507
Windshield Wiper Fuses........................... 503
Electronically Controlled Air Suspension
System.................................................... 372
Engine
Air Cleaner/Filter...................................... 409
Battery..................................................... 431
Check and Service Engine Soon Light........ 215
Coolant.................................................... 415
Coolant Heater......................................... 123
Coolant Temperature Gage...................... 213
Drive Belt Routing.................................... 531
Engine Compartment Overview................ 402
Exhaust................................................... 137
Oil ........................................................... 404
Oil Life System........................................ 407
Overheated Protection Operating Mode...... 420
Overheating............................................. 418
Starting.................................................... 121
Entry/Exit Lighting....................................... 191
Event Data Recorders (EDR)...................... 546
Extender, Safety Belt..................................... 45
Exterior Lamps............................................ 186F
Filter
Engine Air Cleaner................................... 409
Finish Damage............................................ 499
First Aid Kit................................................. 360
Fixed Mast Antenna.................................... 300
Flashers, Hazard Warning........................... 176
Flash-to-Pass.............................................. 180
Flat Tire...................................................... 468
Flat Tire, Changing...................................... 468
Flat Tire, Storing.................................485, 488
Fluid
Automatic Transmission............................ 412
Power Steering........................................ 425
Windshield Washer.................................. 426
Four-Wheel Drive........................................ 438
Four-Wheel Drive, Full-Time........................ 128
Front Axle................................................... 440
Front Mounted Receiver.............................. 360
Fuel............................................................ 394
Additives.................................................. 395
California Fuel.......................................... 395
Filling a Portable Fuel Container.............. 399
560

Mirrors
Automatic Dimming Rearview with
Compass and Temperature Display....... 139
Outside Automatic Dimming Mirror
with Curb View Assist........................... 144
Outside Convex Mirror............................. 143
Outside Heated Mirrors............................ 143
Outside Power Mirrors............................. 142
MyGMLink.com............................................ 539
N
Navigation/Radio System,
see Navigation Manual............................. 271
New Vehicle Break-In.................................. 119
Normal Maintenance
Replacement Parts................................... 530
O
Odometer.................................................... 206
Odometer, Trip............................................ 206
Off-Road Driving.......................................... 317Off-Road Lamps.......................................... 190
Off-Road Recovery...................................... 314
Oil
Engine..................................................... 404
Pressure Gage......................................... 218
Oil, Engine Oil Life System ......................... 407
Older Children, Restraints............................. 46
Online Owner Center................................... 539
OnStar
®System, see OnStar®Manual........ 144
Other Warning Devices................................ 177
Outlet Adjustment........................................ 203
Outlet(s), Accessory Power.......................... 196
Outside
Automatic Dimming Mirror with
Curb View Assist.................................. 144
Convex Mirror.......................................... 143
Heated Mirrors......................................... 143
Power Mirrors.......................................... 142
Overheated Engine Protection
Operating Mode....................................... 420
Owner Checks and Services....................... 523
Owners, Canadian.......................................... 3
564