2008 CHEVROLET SUBURBAN overheating

How to Add Automatic Transmission
Fluid
Refer to the Maintenance Schedule to determine what
kind of transmission uid to use. SeeRecommended
Fluids and Lubricants on page 6-13.
Using a funnel, add uid down the transmission dipstick
tube only after checking the transmission uid while it is
hot. A cold check is used only as a reference. If the uid
level is low, add only enough of the proper uid to bring
the level up to the HOT area for a hot check. It does not
take much uid, generally less than one pint (0.5 L).
Do not overll.
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 6-13.
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.
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. 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 6-13.
Change the uid and lter at the intervals listed in
the Maintenance Schedule. SeeScheduled Maintenance
on page 6-4. Be sure to use the transmission uid
listed inRecommended Fluids and Lubricants on
page 6-13.
5-27

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.
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 5-34.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
®can
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 the vehicle warranty.
Always use DEX-COOL
®(silicate-free) coolant
in the vehicle.
5-31

Adding Coolant
If more coolant is needed, 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.
Coolant Surge Tank Pressure Cap
If your vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual for more information.
Notice:If the pressure cap is not tightly installed,
coolant loss and possible engine damage may
occur. Be sure the cap is properly and tightly
secured.
The coolant surge tank pressure cap must be fully
installed on the coolant surge tank. SeeEngine
Compartment Overview on page 5-16for more
information on location.
Engine Overheating
There is a coolant temperature gage on your vehicle’s
instrument panel. SeeEngine Coolant Temperature
Gage on page 3-43.
In addition, ENGINE OVERHEATED STOP ENGINE,
ENGINE OVERHEATED IDLE ENGINE, and a ENGINE
POWER IS REDUCED message comes on in the Driver
Information Center (DIC) on the instrument panel.
SeeDIC Warnings and Messages on page 3-59.
5-34

Cooling System
If your vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual for more information.
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(s){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. If possible,
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.
5.3L Engine (4.8L, 6.0L and 6.2L Similar)
5-37

Tires
Your new vehicle comes with high-quality tires
made by a leading tire manufacturer. If you ever
have questions about your tire warranty and where
to obtain service, see your vehicle Warranty
booklet for details.
{CAUTION:
Poorly maintained and improperly used
tires are dangerous.
Overloading your vehicle’s tires can
cause overheating as a result of too
much exing. You could have an
air-out and a serious accident. See
Loading the Vehicle on page 4-35.
CAUTION: (Continued)
CAUTION: (Continued)

Underinated tires pose the same
danger as overloaded tires. The
resulting accident could cause serious
injury. Check all tires frequently to
maintain the recommended pressure.
Tire pressure should be checked when
your vehicle’s tires are cold. See
Inflation - Tire Pressure on page 5-74.
Overinated tires are more likely
to be cut, punctured, or broken by
a sudden impact — such as when
you hit a pothole. Keep tires at the
recommended pressure.
Worn, old tires can cause accidents.
If the tire’s tread is badly worn, or
if your vehicle’s tires have been
damaged, replace them.
5-66

Disc, MP3.............................................3-95, 3-99
Doing Your Own Service Work........................... 5-4
Dome Lamp Override......................................3-19
Dome Lamps .................................................3-18
Door
Delayed Locking..........................................2-11
Locks........................................................2-10
Power Door Locks.......................................2-10
Programmable Automatic Door Locks.............2-11
Rear Door Security Locks.............................2-11
Driver Information Center (DIC).........................3-51
DIC Operation and Displays..................3-51, 3-56
DIC Vehicle Customization............................3-67
DIC Warnings and Messages........................3-59
Driving
At Night.....................................................4-26
Before a Long Trip......................................4-28
Defensive..................................................... 4-2
Drunken....................................................... 4-2
Highway Hypnosis.......................................4-28
Hill and Mountain Roads..............................4-29
In Rain and on Wet Roads...........................4-26
Off-Road ....................................................4-13
Recovery Hooks..........................................4-34
Rocking Your Vehicle to Get it Out.................4-34
Winter........................................................4-30
Dual Automatic Climate Control System.............3-24
DVD
Rear Seat Entertainment System..................3-105E
EDR .............................................................7-17
Electrical System
Add-On Equipment.....................................5-119
Center Instrument Panel Fuse Block.............5-121
Fuses and Circuit Breakers.........................5-119
Instrument Panel Fuse Block.......................5-120
Power Windows and Other Power Options....5-119
Underhood Fuse Block...............................5-122
Windshield Wiper Fuses.............................5-119
Electronic Immobilizer
PASS-Key
®III+...........................................2-22
Electronic Immobilizer Operation
PASS-Key
®III+...........................................2-23
Engine
Air Cleaner/Filter.........................................5-22
Check and Service Engine Soon Light............3-44
Coolant......................................................5-31
Coolant Heater............................................2-28
Coolant Temperature Gage...........................3-43
Drive Belt Routing.......................................6-16
Engine Compartment Overview......................5-16
Exhaust.....................................................2-46
Fan Noise..................................................5-41
Oil .............................................................5-17
Oil Life System...........................................5-20
Overheated Protection Operating Mode...........5-36
Overheating................................................5-34
Starting......................................................2-26
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