2006 HUMMER H2 engine overheat

Engine Overheating
You will nd a coolant temperature gage on your
vehicle’s instrument panel. SeeEngine Coolant
Temperature Gage on page 3-37.
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 3-48.
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. 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.
CAUTION: (Continued)
CAUTION: (Continued)
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.
SeeOverheated Engine Protection Operating
Mode on page 5-28for 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. SeeOverheated Engine
Protection Operating Mode on page 5-28for
information on driving to a safe place in an
emergency.
5-27

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 4-63.
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.
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.
5-28

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 FanIf 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. 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.
5-29

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. See
Overheated Engine Protection Operating Mode on
page 5-28for 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.
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. See
Engine Coolant on page 5-24for 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. 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.
5-30

{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.
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. Locate the coolant
surge tank pressure
cap that has this label.
2. You can remove the coolant surge tank pressure
cap when the cooling system, including the coolant
surge tank pressure cap and upper radiator
hose, are no longer hot. Turn the pressure cap
slowly counterclockwise about one full turn.
If you hear a hiss, wait for that to stop. A hiss
means there is still some pressure left.
3. Then keep turning the pressure cap slowly, and
remove it.
5-31

Engine (cont.)
Check and Service Engine Soon Light............3-39
Coolant......................................................5-24
Coolant Heater............................................2-26
Coolant Temperature Gage...........................3-37
Drive Belt Routing.......................................6-15
Engine Compartment Overview......................5-12
Exhaust.....................................................2-37
Oil .............................................................5-14
Oil Life System...........................................5-17
Overheated Protection Operating Mode...........5-28
Overheating................................................5-27
Starting......................................................2-25
Entry/Exit Lighting...........................................3-18
Event Data Recorders (EDR)............................7-10
Extender, Safety Belt.......................................1-31
Exterior Lamps...............................................3-14
F
Filter
Engine Air Cleaner......................................5-19
Finish Damage.............................................5-112
First Aid Kit....................................................4-52
Fixed Mast Antenna.......................................3-114
Flash-to-Pass................................................... 3-8
Flat Tire........................................................5-69Flat Tire, Changing.........................................5-70
Flat Tire, Storing...................................5-96, 5-101
Fluid
Automatic Transmission................................5-22
Power Steering...........................................5-33
Windshield Washer......................................5-34
Four-Wheel Drive............................................5-44
Four-Wheel Drive, Full-Time.............................2-30
Front Axle......................................................5-45
Front Mounted Receiver...................................4-53
Fuel............................................................... 5-5
Additives...................................................... 5-6
California Fuel.............................................. 5-6
Filling a Portable Fuel Container....................5-10
Filling Your Tank........................................... 5-8
Fuels in Foreign Countries.............................. 5-7
Gage.........................................................3-44
Gasoline Octane........................................... 5-5
Gasoline Specications.................................. 5-5
Low Warning Light.......................................3-44
Fuses
Center Instrument Panel Fuse Block.............5-118
Fuses and Circuit Breakers.........................5-115
Instrument Panel Fuse Block.......................5-116
Underhood Fuse Block...............................5-119
Windshield Wiper.......................................5-115
5

Outside
Automatic Dimming Mirror with Curb View
Assist.....................................................2-47
Convex Mirror.............................................2-46
Heated Mirrors............................................2-47
Power Mirrors.............................................2-45
Overheated Engine Protection Operating Mode . . . 5-28
Owner Checks and Services.............................. 6-8
Owners, Canadian............................................... ii
P
Park Aid........................................................3-18
Park (P)
Shifting Into................................................2-35
Shifting Out of............................................2-36
Parking
Brake........................................................2-34
Over Things That Burn.................................2-37
Passing.........................................................4-13
Passlock
®......................................................2-23
Power
Accessory Outlet(s)......................................3-21
Door Locks.................................................. 2-9
Electrical System.......................................5-115
Lumbar Controls........................................... 1-3
Retained Accessory (RAP)............................2-25Power (cont.)
Seat............................................................ 1-2
Steering Fluid.............................................5-33
Windows....................................................2-18
Power Winch Platform.....................................4-54
Programmable Automatic Door Locks.................2-10
Q
Questions and Answers About Safety Belts.........1-18
R
Radios..........................................................3-61
Care of Your Cassette Tape Player...............3-111
Care of Your CD and DVD Player................3-113
Care of Your CDs and DVDs.......................3-113
Navigation/Radio System, see Navigation
Manual...................................................3-88
Radio with Cassette and CD.........................3-63
Radio with Six-Disc CD................................3-76
Rear Seat Audio........................................3-108
Setting the Time..........................................3-62
Theft-Deterrent..........................................3-109
Understanding Reception............................3-111
Reading Lamps..............................................3-18
9