2008 HUMMER H2 engine overheat

If No Steam Is Coming From
Your Engine
The ENGINE OVERHEATED IDLE ENGINE 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 4-55.
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
ENGINE POWER IS REDUCED 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 5-13.
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 Fan{CAUTION:
An electric fan under the hood can start up
and injure you even when the engine is not
running. Keep hands, clothing, and tools away
from any underhood electric 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. Check the
coolant level after the system cools down. Some amount
of coolant may be lost due to overheating.
5-29

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 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 could
require changing sooner, at 30,000 miles (50 000 km)
or 24 months, whichever occurs rst. Any repairs
would not be covered by the warranty. Always
use DEX-COOL
®(silicate-free) coolant in the vehicle.
5-30

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 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.
{CAUTION:
Adding only plain water to the cooling system
can be dangerous. Plain water, or some other
liquid such as alcohol, can boil before the
proper coolant mixture will. The vehicle’s
coolant warning system is set for the proper
coolant mixture. With plain water or the wrong
mixture, the engine could get too hot but you
would not get the overheat warning. The
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.
5-31

E
EDR .............................................................7-16
Electrical System
Add-On Equipment.....................................5-110
Center Instrument Panel Fuse Block.............5-112
Fuses and Circuit Breakers.........................5-110
Instrument Panel Fuse Block.......................5-111
Power Windows and Other Power Options....5-110
Underhood Fuse Block...............................5-113
Windshield Wiper Fuses.............................5-110
Electronically Controlled Air Suspension System . . . 4-54
Engine
Air Cleaner/Filter.........................................5-18
Check and Service Engine Soon Light............3-42
Coolant......................................................5-24
Coolant Heater............................................2-31
Coolant Temperature Gage...........................3-40
Drive Belt Routing.......................................6-15
Engine Compartment Overview......................5-12
Exhaust.....................................................2-43
Fan Noise..................................................5-33
Oil .............................................................5-13
Oil Life System...........................................5-16
Overheated Protection Operating Mode...........5-28
Overheating................................................5-27
Running While Parked..................................2-44
Starting......................................................2-30Entry/Exit Lighting...........................................3-19
Event Data Recorders.....................................7-16
Extender, Safety Belt.......................................1-35
Exterior Lamps...............................................3-15
F
Filter
Engine Air Cleaner......................................5-18
Finish Damage.............................................5-107
First Aid Kit....................................................4-42
Fixed Mast Antenna.......................................3-118
Flashers, Hazard Warning.................................. 3-6
Flash-to-Pass................................................... 3-9
Flat Tire........................................................5-78
Flat Tire, Changing.........................................5-78
Flat Tire, Storing.....................................5-94, 5-96
Fluid.............................................................5-21
Power Steering...........................................5-34
Windshield Washer......................................5-35
Folding Rear Seat............................................ 1-8
Four-Wheel Drive............................................5-46
Four-Wheel Drive, Full-Time.............................2-36
Front Axle......................................................5-47
Front Mounted Receiver...................................4-43
5

O
Odometer......................................................3-33
Odometer, Trip...............................................3-33
Off-Road Driving.............................................4-13
Off-Road Recovery..........................................4-11
Oil
Engine.......................................................5-13
Pressure Gage............................................3-45
Pressure Light.............................................3-46
Oil, Engine Oil Life System..............................5-16
Older Children, Restraints................................1-36
Online Owner Center........................................ 7-4
OnStar, Privacy..............................................7-17
OnStar
®System, see OnStar®Manual...............2-53
Operation, Universal Home Remote System........2-57
Other Warning Devices...................................... 3-6
Outlet Adjustment............................................3-29
Outlets
Accessory Power.........................................3-20
Outside
Automatic Dimming Mirror.............................2-49
Convex Mirror.............................................2-49
Heated Mirrors............................................2-49
Power Foldaway Mirrors...............................2-48
Overheated Engine Protection Operating Mode....5-28
Owner Checks and Services.............................. 6-8
Owners, Canadian............................................... ii
P
Paint, Damage..............................................5-107
Park Aid........................................................2-50
Park Brake....................................................2-40
Park (P)
Shifting Into................................................2-41
Shifting Out of............................................2-42
Parking
Over Things That Burn.................................2-43
Passing.........................................................4-12
PASS-Key
®III+..............................................2-26
PASS-Key®III+ Operation................................2-26
Perchlorate Materials Requirements, California...... 5-4
Power
Door Locks.................................................2-11
Electrical System.......................................5-110
Lumbar Controls........................................... 1-3
Reclining Seatbacks...................................... 1-5
Retained Accessory (RAP)............................2-29
Seat............................................................ 1-2
Steering Fluid.............................................5-34
Windows....................................................2-20
Power Winch Platform.....................................4-43
Privacy..........................................................7-16
Event Data Recorders..................................7-16
Navigation System.......................................7-17
OnStar.......................................................7-17
Radio Frequency Identication.......................7-17
Programmable Automatic Door Locks.................2-11
9