2003 CHEVROLET SUBURBAN engine overheat

Adding Coolant
If you need more coolant, add the proper DEX-COOLž
coolant mixtureat 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. Don't spill coolant on a hot engine.
When replacing the pressure cap, make sure it is
hand-tight.
Coolant Surge Tank Pressure Cap
SeeEngine Compartment
Overview on page 5-14for
more information on
location.
The coolant surge tank pressure cap must be fully
installed on the coolant surge tank.
Notice:Your pressure cap is a pressure-type cap
and must be tightly installed to prevent coolant loss
and possible engine damage from overheating.
See ªCapacities and Speci®cationsº for more
information.
5-32

Engine Overheating
You will ®nd a coolant temperature gage on your
vehicle's instrument panel. SeeEngine Coolant
Temperature Gage on page 3-45. In addition, you will
®nd an ENGINE OVERHEATED, and a REDUCED
ENGINE POWER message in the DIC on the instrument
panel. See
Driver Information Center (DIC) on
page 3-53.
Overheated Engine Protection
Operating Mode (V8 Engines Only)
If an overheated engine condition exists and the
REDUCED ENGINE POWER message is displayed, an
overheat protection mode which alternates ®ring
groups of cylinders helps prevent engine damage. In
this mode, you will notice a loss in power and engine
performance. This operating mode allows your vehicle to
be driven to a safe place in an emergency. Driving
extended miles (km) and/or towing a trailer in the
overheat protection mode should be avoided.
Notice:After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any
repair. The engine oil will be severely degraded.
Repair the cause of coolant loss, change the oil and
reset the oil life system. See ªEngine Oilº in the
Index.
5-33

If Steam Is Coming From Your Engine
{CAUTION:
Steam from an overheated engine can burn
you badly, even if you just open the hood. Stay
away from the engine if you see or hear steam
CAUTION: (Continued)
CAUTION: (Continued)
coming from it. Just turn it off and get
everyone away from the vehicle until it cools
down. Wait until there is no sign of steam or
coolant before you open the hood.
If you keep driving when your engine is
overheated, the liquids in it can catch ®re. You
or others could be badly burned. Stop your
engine if it overheats, and get out of the
vehicle until the engine is cool.
See ªOverheated Engine Protection Operating
Modeº in the Index for information on driving
to a safe place in an emergency.
Notice:If your engine catches ®re because you
keep driving with no coolant, your vehicle can
be badly damaged. The costly repairs would not be
covered by your warranty. See ªOverheated
Engine Protection Operating Modeº in the Index for
information on driving to a safe place in an
emergency.
5-34

If No Steam Is Coming From Your
Engine
An overheat warning, along with a low coolant condition,
can indicate a serious problem. SeeLow CoolantunderDIC Warnings and Messages on page 3-64.
If you get an engine overheat warning with and do not
have a low coolant condition, but see or hear no steam,
the problem may not be too serious. Sometimes the
engine can get a little too hot when you:
·Climb a long hill on a hot day.
·Stop after high-speed driving.
·Idle for long periods in traffic.
·Tow a trailer. SeeTowing a Trailer on page 4-65.
If you get the overheat warning with no sign of steam, try
this for a minute or so:
1. In heavy traffic, let the engine idle in neutral while
stopped. If it is safe to do so, pull off the road. Shift
to park or neutral and let the engine idle.
2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning doesn't come back on, you can drive
normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there's still no sign of steam, you can push down the
accelerator until the engine speed is about twice as
fast as normal idle speed for at least three minutes while
you're parked. If you still have the warning,
turn off
the engine and get everyone out of the vehicleuntil it
cools down. Also, seeOverheated Engine Protection
Operating Modelisted previously in this section.
You may decide not to lift the hood but to get service
help right away.
5-35

The coolant level should
be at or above the FULL
COLD mark. If it isn't,
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 doesn't, your vehicle needs service. Turn off
the engine.
Notice:Engine damage from running your engine
without coolant isn't covered by your warranty.
See ªOverheated Engine Protection Operating
Modeº in the Index for information on driving to a
safe place in an emergency.
Notice:When adding coolant, it is important that
you use only DEX-COOLž(silicate-free) coolant.
If coolant other than DEX-COOLžis added to
the system, premature engine, heater core or
radiator corrosion may result. In addition, the engine
coolant will require change sooner Ð at 30,000 miles
(50 000 km) or 24 months, whichever occurs ®rst.
Damage caused by the use of coolant other
than DEX-COOL
žis not covered by your new vehicle
warranty.
5-37

{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
žcoolant.
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.
5-39

Driving in Mud, Sand, Snow or Ice....................4-38
Driving in Water..............................................4-39
Driving On Grades..........................................4-75
Driving on Off-Road Hills.................................4-30
Driving on Snow or Ice....................................4-52
Driving Through Deep Standing Water...............4-44
Driving Through Flowing Water.........................4-44
Driving Uphill..................................................4-31
Driving with a Trailer.......................................4-73
Driving..........................................................4-40
At Night.....................................................4-40
City...........................................................4-45
Defensive..................................................... 4-2
Drunken....................................................... 4-2
Freeway.....................................................4-46
Hill and Mountain Roads..............................4-49
In Rain and on Wet Roads...........................4-42
Winter........................................................4-51
Dual Automatic Climate Control System.............3-25
Dual Climate Control System............................3-21
DVD Player..................................................3-114
DVD ............................................................3-129
Cleaning the Video Screen..........................3-129
Distortion..................................................3-126
Rear Seat Entertainment System..................3-114E
Easy Exit Seat...............................................2-67
Electrical System...........................................5-108
Add-On Equipment.....................................5-108
Fuses and Circuit Breakers.........................5-109
Power Windows and Other Power Options....5-108
Windshield Wiper Fuses.............................5-108
Electrochromic Mirror Operation................2-46, 2-49
Emissions Inspection and
Maintenance Programs.................................3-50
ENGINE COOLANT HOT.................................3-66
Engine Coolant Level Check.............................6-11
Engine Hour Meter Display...............................3-38
Engine Oil Additives........................................5-21
Engine Oil and Chassis Lubrication Scheduled
Maintenance................................................. 6-5
Engine Oil Level Check...................................6-11
ENGINE OVERHEATED..................................3-66
Engine..........................................................5-23
Air Cleaner/Filter.........................................5-23
Battery.......................................................5-48
Check and Service Engine Soon Light............3-47
Compartment Overview................................5-14
Coolant Heater............................................2-24
6

Engine (cont.)
Coolant Temperature Gage...........................3-45
Coolant......................................................5-29
Cooling System Inspection............................6-17
Exhaust.....................................................2-43
Fan Noise..................................................5-42
Oil .............................................................5-18
Overheating................................................5-33
Starting......................................................2-23
Entering or Exiting the Third Row Seats.............. 1-9
Entertainment System....................................3-129
Cleaning the Video Screen..........................3-129
DVD Distortion..........................................3-126
Entry Lighting.................................................3-17
Environmental Concerns..................................4-27
Erasing HomeLink
žButtons..............................2-60
Exit Lighting...................................................3-17
Express-Down Windows...................................2-17
Extender, Safety Belt.......................................1-46
Exterior Lamps...............................................3-14
F
Filter.............................................................5-23
Engine Air Cleaner......................................5-23
Finding a PTY Station
(RDS and XMŸ).......................3-80, 3-91, 3-104Finding a Station..................3-74, 3-78, 3-89, 3-102
Finish Care..................................................5-103
Finish Damage.............................................5-104
Fixed Mast Antenna.......................................3-129
Flash-To-Pass.................................................. 3-8
Flat Tire, Changing.........................................5-77
Flat Tire........................................................5-76
Fluid.............................................................5-26
Automatic Transmission................................5-26
Power Steering...........................................5-43
Windshield Washer......................................5-44
FM Stereo....................................................3-127
Fog Lamps....................................................3-16
Folding the Seatback.......................................1-16
Folding the Seatbacks.....................1-10, 1-12, 1-21
Following Distance..........................................4-74
Footnotes........................................................ 6-5
Four-Wheel Drive....................................2-29, 5-57
Four-Wheel-Drive Light....................................3-51
Front Axle Locking Feature...............................2-30
Front Axle......................................................5-58
Front Reading Lamps......................................3-18
Front Storage Area.........................................2-61
Frontal Air Bags.............................................1-79
Fuel Information Button....................................3-57
FUEL LEVEL LOW.........................................3-67
7