engine HUMMER H3 2007 Workshop Manual

If you decide you can go down a hill safely, then
try to keep your vehicle headed straight down, and
use a low gear. This way, engine drag can help
your brakes and they will not have to do all
the work. Descend slowly, keeping your vehicle
under control at all times.
{CAUTION:
Heavy braking when going down a hill can
cause your brakes to overheat and fade.
This could cause loss of control and a
serious accident. Apply the brakes lightly
when descending a hill and use a low
gear to keep vehicle speed under control.
Q:Are there some things I should not do
when driving down a hill?
A:Yes! These are important because if you
ignore them you could lose control and
have a serious accident:
When driving downhill, avoid turns that take
you across the incline of the hill. A hill that
is not too steep to drive down may be
too steep to drive across. You could roll over
if you do not drive straight down.
Never go downhill with the transmission in
NEUTRAL (N). This is called “free-wheeling.”
Your brakes will have to do all the work
and could overheat and fade.
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Q:Am I likely to stall when going downhill?
A:It is much more likely to happen going uphill.
But if it happens going downhill, here is
what to do:
1. Stop your vehicle by applying the regular
brakes. Apply the parking brake.
2. If you have an automatic transmission,
shift to PARK (P). While still braking,
restart the engine.
3. Shift back to a low gear, release the
parking brake, and drive straight down.
4. If the engine will not start, get out and
get help.
Driving Across an Incline
Sooner or later, an off-road trail will probably go
across the incline of a hill. If this happens,
you have to decide whether to try to drive across
the incline. Here are some things to consider:
A hill that can be driven straight up or down
may be too steep to drive across. When you
go straight up or down a hill, the length of the
wheel base — the distance from the front
wheels to the rear wheels — reduces the
likelihood the vehicle will tumble end over end.
But when you drive across an incline, the much
more narrow track width — the distance
between the left and right wheels — may not
prevent the vehicle from tilting and rolling over.
Also, driving across an incline puts more weight
on the downhill wheels. This could cause a
downhill slide or a rollover.
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Driving in Mud, Sand, Snow, or Ice
When you drive in mud, snow, or sand, your wheels
will not get good traction. You cannot accelerate as
quickly, turning is more difficult, and you will need
longer braking distances.
It is best to use a low gear when you are in
mud — the deeper the mud, the lower the gear.
In really deep mud, the idea is to keep your vehicle
moving so you do not get stuck. Be careful to
keep mud from building up and washing onto the
engine cooling system.
When you drive on sand, you will sense a change
in wheel traction. But it will depend upon how
loosely packed the sand is. On loosely packed
sand, such as on beaches or sand dunes,
your tires will tend to sink into the sand. This has
an effect on steering, accelerating, and braking.
Drive at a reduced speed and avoid sharp turns
or abrupt maneuvers.Hard packed snow and ice offer the worst tire
traction. On these surfaces, it is very easy to lose
control. On wet ice, for example, the traction is
so poor that you will have difficulty accelerating.
And if you do get moving, poor steering and
difficult braking can cause you to slide out of
control.
{CAUTION:
Driving on frozen lakes, ponds, or rivers
can be dangerous. Underwater springs,
currents under the ice, or sudden thaws
can weaken the ice. Your vehicle could
fall through the ice and you and your
passengers could drown. Drive your
vehicle on safe surfaces only.
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Driving in Water
Heavy rain can mean ash ooding, and ood
waters demand extreme caution.
Find out how deep the water is before you drive
through it. If it is deep enough to cover your wheel
hubs, axles, or exhaust pipe, do not try it — you
probably will not get through. Also, water that deep
can damage your axle and other vehicle parts.
Your vehicle is capable of depths up to 20 inches.
Know how to judge whether the water is deeper
than this before proceeding into it.
If the water is not too deep, drive slowly through it.
At faster speeds, water splashes on your ignition
system and your vehicle can stall. Stalling can also
occur if you get your tailpipe under water. And,
as long as your tailpipe is under water, you
will never be able to start your engine. When you
go through water, remember that when your
brakes get wet, it may take you longer to stop.{CAUTION:
Driving through rushing water can be
dangerous. Deep water can sweep your
vehicle downstream and you and your
passengers could drown. If it is only
shallow water, it can still wash away the
ground from under your tires, and you
could lose traction and roll the vehicle
over. Do not drive through rushing water.
SeeDriving in Rain and on Wet Roads on page 273
for more information on driving through water.
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After Off-Road Driving
Remove any brush or debris that has collected
on the underbody, chassis, or under the hood.
These accumulations can be a re hazard.
After operation in mud or sand, have the brake
linings cleaned and checked. These substances
can cause glazing and uneven braking. Check
the engine and oil coolers for mud accumulation.
Thoroughly and carefully clean these devices
to allow proper cooling. Check the body structure,
steering, suspension, underbody shields,
wheels, tires, and exhaust system for damage.
Also, check the fuel lines and cooling system
for any leakage.
Your vehicle will require more frequent service
due to off-road use. See the Maintenance
Schedule for additional information.
Assist Steps
Your vehicle may be equipped with removable
side steps.
Remove the steps prior to off-roading to give your
vehicle more ground clearance and to prevent
damage to the vehicle from the side steps
dragging and/or catching on obstacles.
Notice:Do not drive off-road with the side
steps attached to your vehicle. You can damage
the side steps and/or your vehicle’s frame if
they get caught or drag against an obstacle.
This damage would not be covered by your
vehicle’s warranty. Always remove the side
steps prior to any off-road driving.
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Driving Through Deep Standing Water
Notice:If you drive too quickly through deep
puddles or standing water, water can come in
through your engine’s air intake and badly
damage your engine. Never drive through water
that is slightly lower than the underbody of your
vehicle. If you cannot avoid deep puddles or
standing water, drive through them very slowly.
Driving Through Flowing Water
{CAUTION:
Flowing or rushing water creates strong
forces. If you try to drive through owing
water, as you might at a low water
crossing, your vehicle can be carried away.
As little as six inches of owing water
can carry away a smaller vehicle. If this
happens, you and other vehicle occupants
could drown. Do not ignore police warning
signs, and otherwise be very cautious
about trying to drive through owing water.
Some Other Rainy Weather Tips
Besides slowing down, allow some extra
following distance. And be especially
careful when you pass another vehicle.
Allow yourself more clear room ahead, and
be prepared to have your view restricted
by road spray.
Have good tires with proper tread depth.
SeeTires on page 367.
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Once you are moving on the freeway, make
certain you allow a reasonable following distance.
Expect to move slightly slower at night.
When you want to leave the freeway, move to
the proper lane well in advance. If you miss
your exit, do not, under any circumstances, stop
and back up. Drive on to the next exit.
The exit ramp can be curved, sometimes quite
sharply. The exit speed is usually posted.
Reduce your speed according to your
speedometer, not to your sense of motion.
After driving for any distance at higher speeds,
you may tend to think you are going slower
than you actually are.
Before Leaving on a Long Trip
Make sure you are ready. Try to be well rested.
If you must start when you are not fresh — such
as after a day’s work — do not plan to make
too many miles that rst part of the journey.
Wear comfortable clothing and shoes you can
easily drive in.Is your vehicle ready for a long trip? If you keep it
serviced and maintained, it is ready to go. If it needs
service, have it done before starting out. Of course,
you will nd experienced and able service experts
in GM dealerships all across North America. They
will be ready and willing to help if you need it.
Here are some things you can check before a trip:
Windshield Washer Fluid:Is the reservoir
full? Are all windows clean inside and outside?
Wiper Blades:Are they in good shape?
Fuel, Engine Oil, Other Fluids:Have you
checked all levels?
Lamps:Are they all working? Are the lenses
clean?
Tires:They are vitally important to a safe,
trouble-free trip. Is the tread good enough
for long-distance driving? Are the tires
all inated to the recommended pressure?
Weather Forecasts:What is the weather
outlook along your route? Should you
delay your trip a short time to avoid a major
storm system?
Maps:Do you have up-to-date maps?
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Highway Hypnosis
Is there actually such a condition as highway
hypnosis? Or is it just plain falling asleep at the
wheel? Call it highway hypnosis, lack of
awareness, or whatever.
There is something about an easy stretch of road
with the same scenery, along with the hum of the
tires on the road, the drone of the engine, and the
rush of the wind against the vehicle that can make
you sleepy. Do not let it happen to you! If it does,
your vehicle can leave the road in less than a
second, and you could crash and be injured.
What can you do about highway hypnosis?
First, be aware that it can happen.
Then here are some tips:
Make sure your vehicle is well ventilated,
with a comfortably cool interior.
Keep your eyes moving. Scan the road
ahead and to the sides. Check your mirrors
and your instruments frequently.
If you get sleepy, pull off the road into a rest,
service, or parking area and take a nap, get
some exercise, or both. For safety, treat
drowsiness on the highway as an emergency.
Hill and Mountain Roads
Driving on steep hills or mountains is different
from driving in at or rolling terrain.
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If you drive regularly in steep country, or if you are
planning to visit there, here are some tips that
can make your trips safer and more enjoyable.
SeeOff-Road Driving on page 250for information
about driving off-road.
Keep your vehicle in good shape. Check all
uid levels and also the brakes, tires, cooling
system, and transmission. These parts can
work hard on mountain roads.
{CAUTION:
If you do not shift down, your brakes
could get so hot that they would not work
well. You would then have poor braking or
even none going down a hill. You could
crash. Shift down to let your engine assist
your brakes on a steep downhill slope.
{CAUTION:
Coasting downhill in NEUTRAL (N) or with
the ignition off is dangerous. Your brakes
will have to do all the work of slowing
down. They could get so hot that they
would not work well. You would then have
poor braking or even none going down a
hill. You could crash. Always have your
engine running and your vehicle in gear
when you go downhill.
Know how to go down hills. The most important
thing to know is this: let your engine do some of
the slowing down. Shift to a lower gear when
you go down a steep or long hill.
Know how to go uphill. You may want to shift
down to a lower gear. The lower gears help
cool your engine and transmission, and you can
climb the hill better.
280

If You Are Caught in a Blizzard
If you are stopped by heavy snow, you could be in
a serious situation. You should probably stay with
your vehicle unless you know for sure that you
are near help and you can hike through the snow.
Here are some things to do to summon help and
keep yourself and your passengers safe:
Turn on your hazard ashers.
Tie a red cloth to your vehicle to alert police
that you have been stopped by the snow.
Put on extra clothing or wrap a blanket
around you. If you do not have blankets or
extra clothing, make body insulators from
newspapers, burlap bags, rags, oor
mats — anything you can wrap around
yourself or tuck under your clothing to
keep warm.You can run the engine to keep warm, but
be careful.
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