2008 HUMMER H2 cooling

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

{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.4. Fill the coolant surge tank with the proper mixture,
to the FULL COLD mark.
5-32

5. With the coolant surge tank pressure cap off, start
the engine and let it run until you can feel the upper
radiator hose getting hot. Watch out for the engine
cooling fan.
By this time, the coolant level inside the coolant
surge tank may be lower. If the level is lower, add
more of the proper mixture to the coolant surge tank
until the level reaches the FULL COLD mark.
6. Then replace the pressure cap. Be sure the
pressure cap is hand-tight and fully seated.
7. Verify coolant level after engine is shut off and the
coolant is cold. If necessary, repeat coolant ll
procedure steps 1 through 7.
Engine Fan Noise
If your vehicle has a clutched engine cooling fan, when
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the fan is spinning slower and the clutch is
not fully engaged. This improves fuel economy and
reduces fan noise. Under heavy vehicle loading, trailer
towing, and/or high outside temperatures, the fan
speed increases as the clutch more fully engages, so
you may hear an increase in fan noise. This is normal
and should not be mistaken as the transmission slipping
or making extra shifts. It is merely the cooling system
functioning properly. The fan will slow down when
additional cooling is not required and the clutch
disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch partially
disengages.
If your vehicle has electric cooling fans, you may hear
the fans spinning at low speed during most everyday
driving. The fans may turn off if no cooling is required.
Under heavy vehicle loading, trailer towing, and/or
high outside temperatures, or if you are operating your
air conditioning system, the fans may change to
high speed and you may hear an increase in fan noise.
This is normal and indicates that the cooling system
is functioning properly. The fans will change to low
speed when additional cooling is no longer required.
5-33

Notice:The wrong wheel can also cause problems
with bearing life, brake cooling, speedometer or
odometer calibration, headlamp aim, bumper height,
vehicle ground clearance, and tire or tire chain
clearance to the body and chassis.
SeeChanging a Flat Tire on page 5-78for more
information.
Used Replacement Wheels
{CAUTION:
Putting a used wheel on your vehicle is
dangerous. You cannot know how it has been
used or how far it has been driven. It could fail
suddenly and cause a crash. If you have to
replace a wheel, use a new GM original
equipment wheel.
Tire Chains
Notice:Use tire chains only where legal and only
when you must. Use only SAE Class U-type
chains that are the proper size for your tires. Install
them on the rear axle tires and tighten them as
tightly as possible with the ends securely fastened.
Drive slowly and follow the chain manufacturer’s
instructions. If you can hear the chains contacting
your vehicle, stop and retighten them. If the contact
continues, slow down until it stops. Driving too
fast or spinning the wheels with chains on will
damage your vehicle.
5-75

Fuses Usage
39 Instrument Panel Cluster
40 Run, Accessory
41 Auxiliary Climate Control (Ignition)
42 Rear Defogger
43 SEO B1 Uptter Usage (Battery)
44 Cigarette Lighter, Auxiliary Power Outlet
45 Special Equipment Option (SEO)
46 Climate Controls (Ignition)
47 Engine Control Module (Ignition)
50 Cooling Fan 1 (J-Case)
51Electronically Controlled Air Suspension
(J-Case)
52Vehicle Stability System, Antilock Brake
System-1 (J-Case)
53 Cooling Fan 2 (J-Case)
54 Starter (J-Case)
55 Stud 2 Trailer Brake Module (J-Case)
56 Left Bussed Electrical Center 1 (J-Case)
57Heated Windshield Washer System
(J-Case)Fuses Usage
58 Four-Wheel Drive System (J-Case)
59Stud 1 Trailer Connector Battery Power
(J-Case)
60 Mid Bussed Electrical Center 1 (J-Case)
61 Climate Control Blower (J-Case)
62 Left Bussed Electrical Center 2 (J-Case)
Relays Usage
FAN HI Cooling Fan High Speed
FAN LO Cooling Fan Low Speed
FAN CNTRL Cooling Fan Control
HDLP LO Low-Beam Headlamp
A/C CMPRSR Air Conditioning Compressor
STRTR Starter
PWR/TRN Powertrain
PRK LAMP Parking Lamps
REAR DEFOG Rear Defogger
RUN/CRNK Switched Power
5-116

Capacities and Specications
The following approximate capacities are given in English and metric. Please refer toRecommended Fluids and
Lubricants on page 6-12for more information.
Capacities and Specications
ApplicationCapacities
English Metric
Air Conditioning Refrigerant R134aFor the air conditioning system refrigerant charge
amount, see the refrigerant caution label located
under the hood. See your dealer/retailer for more
information.
Cooling System
1
SUV Model 16.7 qt 15.8 L
SUT Model 15.4 qt 14.6 L
Engine Oil with Filter
26.0 qt 5.7 L
Fuel Tank 32.0 gal 121.0 L
Transmission Fluid (Pan Removal and Filter Replacement) 6.0 qt 5.7 L
5-117

Capacities and Specications (cont’d)
ApplicationCapacities
English Metric
Transfer Case Fluid 1.5 qt 1.4 L
Wheel Nut Torque 140 lb ft 190Y
1After rell, the level must be rechecked. SeeCooling System on page 5-29.2After rell, the level must be rechecked. Add enough engine oil so that the uid is within the proper operating
range. SeeEngine Oil on page 5-13.
All capacities are approximate. When adding, be sure to ll to the appropriate level, as recommended in this
manual.
Engine Specications
Engine VIN Code Transmission Spark Plug Gap
VORTEC™ 6.2L V8 8 Automatic 0.040 inches (1.01 mm)
5-118