2008 CHEVROLET SILVERADO engine overheat

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 the 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.There some things not to do when driving down a hill.
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.”
The brakes will have to do all the work and could
overheat and fade.
Your vehicle is much more likely to stall when going
uphill. But if it happens when going downhill:
1. Stop your vehicle by applying the regular brakes.
Apply the parking brake.
2. Shift to PARK (P) and, 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.
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Then, shut the engine off and close the window almost
all the way to preserve the heat. Start the engine
again and repeat this only when you feel really
uncomfortable from the cold. But do it as little as
possible. Preserve the fuel as long as you can. To help
keep warm, you can get out of the vehicle and do
some fairly vigorous exercises every half hour or so until
help comes.
If Your Vehicle is Stuck in Sand,
Mud, Ice, or Snow
Slowly and cautiously spin the wheels to free your
vehicle when stuck in sand, mud, ice, or snow. See
Rocking Your Vehicle to Get It Out on page 4-34.
If your vehicle has a traction system, it can often help to
free a stuck vehicle. Refer to your vehicle’s traction
system in the Index. If the stuck condition is too severe
for the traction system to free the vehicle, turn the
traction system off and use the rocking method.
{CAUTION:
If you let your vehicle’s tires spin at high
speed, they can explode, and you or others
could be injured. The vehicle can overheat,
causing an engine compartment re or other
damage. Spin the wheels as little as possible
and avoid going above 35 mph (55 km/h) as
shown on the speedometer.
For information about using tire chains on your vehicle,
seeTire Chains on page 5-92.
Rocking Your Vehicle to Get It Out
First, turn the steering wheel left and right to clear
the area around the front wheels. For four-wheel-drive
vehicles, shift into Four-Wheel High. For vehicles
with StabiliTrak
®, turn the traction control part of the
system off. SeeStabiliTrak®System on page 4-6. Then
shift back and forth between REVERSE (R) and a
forward gear, spinning the wheels as little as possible.
4-34

Turn Signals When Towing a Trailer
The arrows on your instrument panel will ash whenever
you signal a turn or lane change. Properly hooked up,
the trailer lamps will also ash, telling other drivers
you’re about to turn, change lanes or stop.
When towing a trailer, the arrows on your instrument
panel will ash for turns even if the bulbs on the trailer
are burned out. Thus, you may think drivers behind
you are seeing your signal when they are not. It’s
important to check occasionally to be sure the trailer
bulbs are still working.
Driving On Grades
Reduce speed and shift to a lower gearbeforeyou start
down a long or steep downgrade. If you don’t shift
down, you might have to use your brakes so much that
they would get hot and no longer work well.You can tow in DRIVE (D). You may want to shift the
transmission to lower gear selection if the transmission
shifts too often (e.g., under heavy loads and/or hilly
conditions).
You may also want to activate the tow/haul mode if the
transmission shifts too often. See “Tow/Haul Mode”
later in this section.
When towing at high elevation on steep uphill grades,
consider the following: Engine coolant at higher
elevations will boil at a lower temperature than at or
near sea level. If you turn your engine off immediately
after towing at high elevation on steep uphill grades,
your vehicle may show signs similar to engine
overheating. To avoid this, let the engine run while
parked, preferably on level ground, with the transmission
in PARK (P) at least ve minutes before turning the
engine off. If you do get the overheat warning, see
Engine Overheating on page 5-32.
4-88

Service............................................................5-4
Accessories and Modications..........................5-4
California Proposition 65 Warning.....................5-4
California Perchlorate Materials Requirements.....5-5
Doing Your Own Service Work.........................5-5
Adding Equipment to the Outside of
Your Vehicle..............................................5-5
Fuel................................................................5-6
Gasoline Octane............................................5-6
Gasoline Specications....................................5-6
California Fuel...............................................5-7
Additives.......................................................5-7
Fuel E85 (85% Ethanol)..................................5-8
Fuels in Foreign Countries...............................5-9
Filling the Tank............................................5-10
Filling a Portable Fuel Container.....................5-12
Checking Things Under the Hood....................5-12
Hood Release..............................................5-13
Engine Compartment Overview.......................5-14
Engine Oil (Gasoline Engine)..........................5-15
Engine Oil Life System..................................5-18
Engine Air Cleaner/Filter (Gasoline Engines).....5-20
Automatic Transmission Fluid
(6-Speed Transmission)..............................5-22Automatic Transmission Fluid
(4-Speed Transmission)..............................5-26
Engine Coolant.............................................5-29
Coolant Surge Tank Pressure Cap..................5-32
Engine Overheating.......................................5-32
Overheated Engine Protection
Operating Mode (V8 Engines Only)..............5-34
Cooling System............................................5-35
Engine Fan Noise.........................................5-40
Power Steering Fluid.....................................5-41
Windshield Washer Fluid................................5-42
Brakes........................................................5-43
Battery........................................................5-46
Jump Starting...............................................5-47
Rear Axle.......................................................5-52
Four-Wheel Drive............................................5-54
Front Axle......................................................5-56
Noise Control System.....................................5-57
Tampering with Noise Control System
Prohibited.................................................5-57
Headlamp Aiming...........................................5-58
Section 5 Service and Appearance Care
5-1

3. Remove the engine air cleaner/lter from the
housing. Care should be taken to dislodge as
little dirt as possible.
4. Clean the engine air cleaner/lter sealing surfaces
and the housing.
5. Inspect or replace the engine air cleaner/lter.
6. Reinstall the cover and tighten the screws.
7. Reset the air lter restriction indicator, if the vehicle
has one, by pressing the top button on the indicator.
{CAUTION:
Operating the engine with the air cleaner/lter
off can cause you or others to be burned.
The air cleaner not only cleans the air; it helps
to stop ames if the engine backres. If it is
not there and the engine backres, you could
be burned. Do not drive with it off, and be
careful working on the engine with the air
cleaner/lter off.
Automatic Transmission Fluid
(6-Speed Transmission)
When to Check and Change Automatic
Transmission Fluid
It is usually not necessary to check the transmission
uid level. The only reason for uid loss is a
transmission leak or overheating the transmission.
If you suspect a small leak, then use the following
checking procedures to check the uid level.
5-22

However, if there is a large leak, then it may be
necessary to have the vehicle towed to a dealer/retailer
service department and have it repaired before driving
the vehicle further.
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 in
Recommended Fluids and Lubricants on page 6-14.
Change the uid and lter at the intervals listed in
the Maintenance Schedule. SeeScheduled Maintenance
(Gasoline Engine) on page 6-4. Be sure to use the
transmission uid listed inRecommended Fluids and
Lubricants on page 6-14.
How to Check Automatic
Transmission Fluid
Notice:Too much or too little uid can damage
your transmission. Too much can mean that some
of the uid could come out and fall on hot engine
parts or exhaust system parts, starting a re.
Too little uid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission uid.Before checking the uid level, prepare your vehicle
as follows:
1. Start the engine and park your vehicle on a level
surface. Keep the engine running.
2. Apply the parking brake and place the shift lever
in P (PARK).
3. With your foot on the brake pedal, move the shift
lever through each gear range, pausing for about
three seconds in each range. Then, move the
shift lever back to P (PARK).
4. Allow the engine to idle (500 – 800 rpm) for at least
one minute. Slowly release the brake pedal.
5. Keep the engine running and press the Trip/Fuel
button or trip odometer reset stem until TRANS
TEMP (Transmission Temperature) displays on the
Driver Information Center (DIC).
6. Using the TRANS TEMP reading, determine and
perform the appropriate check procedure. If the
TRANS TEMP reading is not within the required
temperature ranges, allow the vehicle to cool,
or operate the vehicle until the appropriate
transmission uid temperature is reached.
5-23

Consistency of Readings
Always check the uid level at least twice using the
procedures described. Consistency (repeatable
readings) is important to maintaining proper uid level.
If uid is added, it may take 15 minutes or longer to
obtain an accurate reading because of residual
uid draining down the dipstick tube. If inconsistent
readings persist, check the transmission breather to be
sure it is clean and not clogged. If readings are still
inconsistent, contact your dealer/retailer.
Automatic Transmission Fluid
(4-Speed Transmission)
When to Check and Change
Automatic Transmission Fluid
A good time to check your automatic transmission uid
level is when the engine oil is changed.
Change the uid and lter at the intervals listed in
Additional Required Services on page 6-6, and be sure
to use the transmission uid listed inRecommended
Fluids and Lubricants on page 6-14.
How to Check Automatic
Transmission Fluid
Because this operation can be a little difficult, you may
choose to have this done at the dealer/retailer service
department.
If you do it yourself, be sure to follow all the instructions
here, or you could get a false reading on the dipstick.
Notice:Too much or too little uid can damage
your transmission. Too much can mean that some
of the uid could come out and fall on hot engine
parts or exhaust system parts, starting a re.
Too little uid could cause the transmission to
overheat. Be sure to get an accurate reading if you
check your transmission uid.
Wait at least 30 minutes before checking the
transmission uid level if you have been driving:
When outside temperatures are above 90°F (32°C).
At high speed for quite a while.
In heavy traffic — especially in hot weather.
While pulling a trailer.
To get the right reading, the uid should be at normal
operating temperature, which is 180°F to 200°F
(82°C to 93°C).
5-26

Engine Coolant
If your vehicle has the DURAMAX®Diesel engine, see
the DURAMAX®Diesel manual for more information.
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 5-32.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.
5-29