2003 GMC ENVOY radiator

How to Add Coolant to the Coolant
Recovery Tank
If you haven't found a problem yet, but the coolant level
isn't at the FULL COLD mark, add a 50/50 mixture of
clean, drinkable waterand DEX-COOLžengine coolant
at the coolant recovery tank. SeeEngine Coolant on
page 5-24for more information.
{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 wouldn't 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.
{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.
5-31

When the coolant in the coolant recovery tank is at the
FULL COLD mark, start your vehicle.
If the overheat warning continues, there's one more
thing you can try. You can add the proper coolant
mixture directly to the radiator, but be sure the cooling
system is cool before you do it.
{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. 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.
5-32

How to Add Coolant to the Radiator
1. You can remove the radiator pressure cap when
the cooling system, including the radiator pressure
cap and upper radiator hose, is 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.2. Then keep turning the pressure cap. Remove the
pressure cap.
5-33

3. Fill the radiator with the proper DEX-COOLž
coolant mixture, up to the base of the ®ller
neck. SeeEngine Coolant on page 5-24for more
information about the proper coolant mixture.4. Then ®ll the coolant recovery tank to the FULL
COLD mark.
5. Put the cap back on the coolant recovery tank, but
leave the radiator pressure cap off.
5-34

6. Start the engine and let it run until you can feel the
upper radiator hose getting hot. Watch out for the
engine cooling fan.
7. By this time, the coolant level inside the radiator
®ller neck may be lower. If the level is lower, add
more of the proper DEX-COOL
žcoolant mixture
through the ®ller neck until the level reaches
the base of the ®ller neck.
8. Then replace the pressure cap. At any time during
this procedure if coolant begins to ¯ow out of the
®ller neck, reinstall the pressure cap. Be sure
the pressure cap is hand-tight.
Engine Fan Noise
This vehicle has a clutched engine cooling fan. When
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions the clutch is not engaged. This improves fuel
economy and reduces fan noise. Under heavy vehicle
loading, trailer towing, and/or high outside temperatures,
the fan speed increases when the clutch engages. So
you may hear an increase in fan noise. This is
normal and should not be mistaken as the transmission
slipping or making extra shifts. It is merely the cooling
system functioning properly. The fan will slow down
when additional cooling is not required and the clutch
disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch disengages.
5-35

100,000 Miles (166 000 km)
qV8 Engine Only: Inspect spark plug wires.An
Emission Control Service.
qReplace spark plugs.An Emission Control Service.
qChange automatic transmission ¯uid and ®lter if
the vehicle is mainly driven under one or more
of these conditions:
þ In heavy city traffic where the outside
temperature regularly reaches 90ÉF (32ÉC) or
higher.
þ In hilly or mountainous terrain.
þ When doing frequent trailer towing.
þ Uses such as found in taxi, police or delivery
service.
qIf you haven't used your vehicle under severe service
conditions listed previously and, therefore, haven't
changed your automatic transmission ¯uid, change
both the ¯uid and ®lter
qAutomatic Transfer Case Only: Change transfer case
¯uid.
qV8 Engine Only: Inspect Positive Crankcase
Ventilation (PCV) valve.
An Emission Control Service.
150,000 Miles (240 000 km)
qDrain, ¯ush and re®ll cooling system (or every
60 months since last service, whichever occurs ®rst).
See
Engine Coolant on page 5-24for what to use.
Inspect hoses. Clean radiator, condenser, pressure
cap and neck. Pressure test the cooling system
and pressure cap.
An Emission Control Service.
qInspect engine accessory drive belt.An Emission
Control Service.
6-10

Engine Cooling System Inspection
Inspect the hoses and have them replaced if they
are cracked, swollen or deteriorated. Inspect all pipes,
®ttings and clamps; replace as needed. Clean the
outside of the radiator and air conditioning condenser.
To help ensure proper operation, a pressure test of
the cooling system and pressure cap is recommended
at least once a year.
Transfer Case and Front Axle
(Four-Wheel Drive) Inspection
Every 12 months or at engine oil change intervals,
check front axle and transfer case and add lubricant
when necessary. A ¯uid loss could indicate a problem;
check and have it repaired, if needed. Check vent
hose at transfer case for kinks and proper installation.
More frequent lubrication may be required on
off-road use.
Brake System Inspection
Inspect the complete system. Inspect brake lines and
hoses for proper hook-up, binding, leaks, cracks,
cha®ng, etc. Inspect disc brake pads for wear and rotors
for surface condition. Inspect other brake parts,
including calipers, parking brake, etc. Check parking
brake adjustment. You may need to have your brakes
inspected more often if your driving habits or
conditions result in frequent braking.
6-17

Gate Operator and Canadian Programming........2-43
Getting Familiar with Off-Road Driving................4-17
Glove Box.....................................................2-44
GM Mobility Program for Persons with
Disabilities.................................................... 7-5
H
Hazard Warning Flashers................................... 3-6
Head Restraints............................................... 1-5
Headlamp High/Low-Beam Changer.................... 3-8
Headlamp Washer..........................................3-11
Headlamps....................................................5-50
Bulb Replacement.......................................5-50
Electrical System.........................................5-89
Front Turn Signal and Sidemarker Lamps.......5-51
Halogen Bulbs............................................5-50
Headphones...................................................3-92
Heated Seats................................................... 1-3
Highway Hypnosis...........................................4-36
Hill and Mountain Roads..................................4-37
Hitches..........................................................4-55
HomeLink Transmitter, Programming..................2-41
HomeLink
žTransmitter....................................2-40
Hood............................................................5-10
Checking Things Under................................5-10
Release.....................................................5-10
Horn............................................................... 3-7How to Add Coolant to the Coolant
Recovery Tank............................................5-31
How to Add Coolant to the Radiator..................5-33
How to Add Fluid............................................5-23
How to Check Lubricant...................................5-48
How to Check Power Steering Fluid..................5-36
How to Check........................................5-22, 5-55
How to Inspect...............................................5-20
How to Use This Manual...................................... ii
How to Wear Safety Belts Properly...................1-14
Hydroplaning..................................................4-31
I
ICE POSSIBLE..............................................3-62
If No Steam Is Coming From Your Engine..........5-28
If Steam Is Coming From Your Engine...............5-27
If the Light Is Flashing.....................................3-43
If the Light Is On Steady.................................3-43
If You Are Stuck in Sand, Mud, Ice or Snow.......4-44
If You Do Decide To Pull A Trailer.....................4-51
If You're Caught in a Blizzard...........................4-41
Ignition Positions.............................................2-19
Ignition Transmission Lock Check......................6-14
Infants and Young Children, Restraints...............1-32
In¯ation -- Tire Pressure..................................5-55
7