2007 HUMMER H2 radiator

At approximately 265°F (130°C), the Driver
Information Center (DIC) will display a
TRANSMISSION HOT message and the
transmission will enter a transmission protection
mode. When the transmission enters the protection
mode, you may notice a change in the transmission
shifting patterns. The transmission will return to
normal shifting patterns when the transmission uid
temperature falls below 260°F (125°C).
If the transmission uid reaches temperatures of
approximately 275°F (135°C) or greater, the DIC
will display a TRANS HOT IDLE ENGINE warning
message and a chime will sound. Pull the vehicle
off the roadway when it is safe to do so. Set the
parking brake, place the transmission in PARK (P)
and allow the engine to idle until the transmission
temperature falls below 260°F (125°C). If the
transmission continues to operate above 265°F
(130°C), please contact your nearest dealer or the
GM Roadside Assistance Center.
SeeDriver Information Center (DIC) on page 222
for further information.Notice:If you drive your vehicle with the
transmission temperature gage above normal
operating range, you can damage the
transmission. This could lead to costly repairs
that would not be covered by your warranty.
Do not drive your vehicle while the
transmission temperature gage reading is
above normal. See your dealer for service.
The following situations can cause the
transmission to operate at higher temperatures:
Towing a trailer,
hot outside air temperatures,
hauling a large or heavy load,
low transmission uid level,
high transmission uid level,
restricted air ow to the radiator.
A temporary solution to hotter transmission
operating temperatures may be to let the
transmission cool down. If the transmission is
operated at higher temperatures on a frequent
basis, seeScheduled Maintenance on page 517
for the proper transmission maintenance intervals.
214

TRANSMISSION HOT
Notice:If you drive your vehicle while the
transmission uid is overheating and the
transmission temperature warning is displayed
on the instrument panel cluster and/or DIC,
you can damage the transmission. This could
lead to costly repairs that would not be
covered by your warranty. Do not drive your
vehicle with overheated transmission uid
or while the transmission temperature warning
is displayed.
This message displays if the transmission uid
temperature becomes high.
When the transmission enters the protection
mode, you may notice a change in the
transmission shifting patterns. When the
transmission uid temperature returns to normal,
the display turns off and the transmission
shifting patterns return to normal.If the vehicle has the Tow/Haul mode, use this
feature if the transmission is operating at higher
temperatures and/or the following situations
exist, which can cause the transmission to operate
at higher temperatures:
Towing a trailer
Hot outside air temperatures
Hauling a large or heavy load
Over-loading
Low transmission uid level
High transmission uid level
Restricted air ow to the radiator and the
auxiliary transmission oil cooler, if your vehicle
has this feature
A temporary solution to hotter transmission
operating temperatures may be to let the
transmission cool down. If the transmission is
operated at higher temperatures on a frequent
basis, seeScheduled Maintenance on page 517
for the proper transmission maintenance intervals
for the transmission on your vehicle. Also see
Transmission Temperature Gage on page 213for
more information.
233

Notice:Use of the incorrect automatic
transmission uid may damage your vehicle,
and the damages may not be covered by
your warranty. Always use the automatic
transmission uid listed inRecommended
Fluids and Lubricants on page 528.
After adding uid, recheck the uid level as
described under “How to Check Automatic
Transmission Fluid,” earlier in this section.
When the correct uid level is obtained, push
the dipstick back in all the way; then ip the
handle down to lock the dipstick in place.
Engine Coolant
The cooling system in your vehicle is lled with
DEX-COOL®engine coolant. This coolant is
designed to remain in your vehicle for ve years or
150,000 miles (240 000 km), whichever occurs rst,
if you add only DEX-COOL
®extended life coolant.
The following explains your cooling system and
how to add coolant when it is low. If you have a
problem with engine overheating, seeEngine
Overheating on page 418.A 50/50 mixture of clean, drinkable water and
DEX-COOL
®coolant will:
Give freezing protection down to
−34°F (−37°C).
Give boiling protection up to 265°F (129°C).
Protect against rust and corrosion.
Help keep the proper engine temperature.
Let the warning lights and gages work as
they should.
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
the rst maintenance service after each
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.
415

What Kind of Coolant to Use
Use a mixture of one-half clean, drinkable water
and one-half DEX-COOL®coolant which will
not damage aluminum parts. If you use this coolant
mixture, you do not need to add anything else.
{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:If you use an improper coolant
mixture, your engine could overheat and be
badly damaged. The repair cost would not be
covered by your warranty. Too much water
in the mixture can freeze and crack the engine,
radiator, heater core, and other parts.
If you have to add coolant more than four times a
year, have your dealer check your cooling
system.
Notice:If you use extra inhibitors and/or
additives in your vehicle’s cooling system, you
could damage your vehicle. Use only the
proper mixture of the engine coolant listed in
this manual for the cooling system. See
Recommended Fluids and Lubricants on
page 528for more information.
416

Checking Coolant
The coolant surge tank
is located in the engine
compartment on the
passenger’s side of the
vehicle. SeeEngine
Compartment Overview
on page 402for more
information on location.
{CAUTION:
Turning the surge tank pressure cap when
the engine and radiator are hot can allow
steam and scalding liquids to blow out
and burn you badly. Never turn the surge
tank pressure cap — even a little — when
the engine and radiator are hot.The vehicle must be on a level surface. When
your engine is cold, the coolant level should be at
the FULL COLD mark.
Adding Coolant
If you need more coolant, add the proper
DEX-COOL®coolant mixture at the surge tank,
but only when the engine is cool.
{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.
When replacing the pressure cap, make sure it is
hand-tight and fully seated.
417

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

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.
423