2004 HUMMER H2 engine overheat

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 5-14.
If Steam Is Coming From Your Engine
5-28

{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. Just 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 your 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.
See “Overheated Engine Protection Operating
Mode” underEngine Overheating on page 5-27
for information on driving to a safe place in an
emergency.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. See “Overheated
Engine Protection Operating Mode” underEngine
Overheating on page 5-27for information on driving
to a safe place in an emergency.
If No Steam Is Coming From Your
Engine
An overheat warning, along with a low coolant condition,
can indicate a serious problem.
If you get an engine overheat, 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 4-75.
5-29

If you get the overheat warning 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 window as necessary.
2. If you’re 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 doesn’t come back on, you can drive
normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there’s 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’re parked. If you still have the warning,turn off the
engine and get everyone out of the vehicleuntil it
cools down. Also, see “Overheated Engine Protection
Operating Mode” listed previously in this section.
You may decide not to lift the hood but to get service
help right away.Cooling System
When you decide it’s safe to lift the hood, here’s what
you’ll see:
A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine Fan
If the coolant inside the coolant surge tank is boiling,
don’t do anything else until it cools down. The vehicle
should be parked on a level surface.
5-30

The coolant level should
be at or above the FULL
COLD mark. If it isn’t,
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 doesn’t, your vehicle needs service. Turn off
the engine.
Notice:Engine damage from running your engine
without coolant is not covered by your warranty. See
“Overheated Engine Protection Operating Mode”
in the Index for 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 may
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.
5-31

{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.
Yourvehicle’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.
Notice:In cold weather, water can freeze and crack
the engine, radiator, heater core and other parts.
Use the recommended coolant and the proper
coolant mixture.
{CAUTION:
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.
1. Park the vehicle on a level surface.
2. Locate the coolant
surge tank pressure
cap that has this label.
You can remove the coolant surge tank pressure
capwhen the cooling system, including the
coolant surge tank pressure cap and upper radiator
hose, are no longer hot. Turn the pressure cap
slowly counterclockwise (left) about one full turn. If
you hear a hiss, wait for that to stop. A hiss
means there is still some pressure left.
5-33

Driver
Position, Safety Belt.....................................1-22
DRIVER DOOR AJAR.....................................3-60
Driver Information Center (DIC).........................3-44
DIC Operation and Displays..........................3-44
DIC Warnings and Messages........................3-56
Driving
At Night.....................................................4-41
City...........................................................4-46
Defensive..................................................... 4-2
Drunken....................................................... 4-3
Freeway.....................................................4-47
Hill and Mountain Roads..............................4-50
In Rain and on Wet Roads...........................4-43
Off-Road....................................................4-17
Winter........................................................4-52
Driving Across an Incline..................................4-36
Driving Downhill..............................................4-35
Driving in Mud, Sand, Snow or Ice....................4-39
Driving in Water..............................................4-40
Driving On Grades..........................................4-83
Driving on Off-Road Hills.................................4-31
Driving on Snow or Ice....................................4-52
Driving Through Deep Standing Water...............4-45
Driving Through Flowing Water.........................4-45
Driving Uphill..................................................4-32
Driving with a Trailer.......................................4-81E
Easy Exit Seat...............................................2-53
Electrical System
Add-On Equipment.....................................5-101
Fuses and Circuit Breakers.........................5-102
Power Windows and Other Power Options....5-102
Windshield Wiper Fuses.............................5-102
Electronically Controlled Air Suspension System....4-74
Emissions Inspection and Maintenance
Programs...................................................3-40
Engine
Air Cleaner/Filter.........................................5-19
Battery.......................................................5-42
Check and Service Engine Soon Light............3-38
Coolant......................................................5-24
Coolant Heater............................................2-21
Coolant Temperature Gage...........................3-35
Drive Belt Routing.......................................6-15
Engine Compartment Overview......................5-12
Exhaust.....................................................2-33
Fan Noise..................................................5-35
Oil .............................................................5-14
Overheating................................................5-27
Starting......................................................2-20
ENGINE COOLANT HOT.................................3-57
Engine Oil Additives........................................5-17
5

ENGINE OVERHEATED..................................3-57
Entering or Exiting the Third Row Seats.............. 1-7
Entry/Exit Lighting...........................................3-17
Environmental Concerns..................................4-23
Erasing HomeLink
®Buttons..............................2-45
Event Data Records (EDR)................................ 7-9
Extender, Safety Belt.......................................1-37
Exterior Lamps...............................................3-13
F
Filter
Engine Air Cleaner......................................5-19
Finding a Program Type (PTY) Station.......3-66, 3-78
Finding a Station....................................3-64, 3-75
Finish Care....................................................5-96
Finish Damage...............................................5-99
First Aid Kit and Tool Kit..................................4-59
Fixed Mast Antenna........................................3-92
Flash-to-Pass................................................... 3-7
Flat Tire........................................................5-78
Flat Tire, Changing.........................................5-79
Fluid
Automatic Transmission................................5-21
Power Steering...........................................5-36
Windshield Washer......................................5-37
FM ...............................................................3-90
Folding the Seatback.......................................1-10
Folding the Seatbacks....................................... 1-8Following Distance..........................................4-82
Front Axle......................................................5-51
Front Receiver................................................4-60
Fuel............................................................... 5-5
Additives...................................................... 5-6
California Fuel.............................................. 5-6
Filling a Portable Fuel Container..................... 5-9
Filling Your Tank........................................... 5-7
Fuels in Foreign Countries.............................. 5-7
Gage.........................................................3-43
Gasoline Octane........................................... 5-5
Gasoline Specications.................................. 5-5
Low Warning Light.......................................3-43
Fuel Information Button....................................3-47
FUEL LEVEL LOW.........................................3-58
Fuses
Fuses and Circuit Breakers.........................5-102
Windshield Wiper.......................................5-102
G
Gage
Engine Coolant Temperature.........................3-35
Fuel..........................................................3-43
Oil Pressure...............................................3-41
Speedometer..............................................3-28
Tachometer.................................................3-28
Transmission Temperature.............................3-36
Voltmeter Gage...........................................3-32
6

Off-Road Recovery..........................................4-14
Oil
Engine.......................................................5-14
Pressure Gage............................................3-41
OIL LIFE RESET............................................3-56
OIL PRESSURE LOW.....................................3-56
Older Children, Restraints................................1-38
Online Owner Center........................................ 7-3
OnStar
®Personal Calling.................................2-41
OnStar®Services............................................2-40
OnStar®Steering Wheel Controls......................2-41
OnStar®System.............................................2-40
Other Warning Devices...................................... 3-5
Outlet Adjustment............................................3-25
Outside
Automatic Dimming Mirror with Curb View
Assist.....................................................2-39
Convex Mirror.............................................2-38
Heated Mirrors............................................2-39
Power Mirrors.............................................2-37
Overheated Engine Protection Operating Mode . . . 5-28
Overload and Overheat Protection.....................4-74
Overseas – Customer Assistance........................ 7-4
Owner Checks and Services.............................. 6-9
Owners, Canadian............................................... ii
Owner’s Information........................................7-11
P
Park (P)
Shifting Into................................................2-30
Shifting Out of............................................2-32
Parking
Brake........................................................2-29
Over Things That Burn.................................2-32
Parking on Hills..............................................4-83
PASSENGER DOOR AJAR..............................3-61
Passing.................................................4-14, 4-82
Passlock
®......................................................2-18
Personalization Button.....................................3-48
Personalization, Climate Controls......................3-25
Plan Ahead When Possible................................ 7-7
Playing a Cassette Tape..................................3-69
Playing a CD.........................................3-72, 3-80
Playing a Specic Loaded CD..........................3-82
Playing the Radio...................................3-63, 3-74
Power
Accessory Outlets........................................3-18
Door Locks.................................................. 2-8
Electrical System.......................................5-102
Lumbar Controls........................................... 1-3
Seat............................................................ 1-2
Steering Fluid.............................................5-36
Windows....................................................2-15
10