2003 GMC SONOMA Owner's Manual

{CAUTION:
Heater and radiator hoses, and other engine
parts, can be very hot. Don’t touch them. If you
do, you can be burned.
Don’t run the engine if there is a leak. If you
run the engine, it could lose all coolant. That
could cause an enginere, and you could be
burned. Get any leakxed 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.
Notice:When adding coolant, it is important that
you use only DEX-COOL®(silicate-free) coolant.
If coolant other than DEX-COOL®is added to
the system, premature engine, heater core or
radiator corrosion may result. In addition, the engine
coolant will require change sooner—at 30,000 miles
(50 000 km) or 24 months, whichever occursrst.
Damage caused by the use of coolant other
than DEX-COOL
®is not covered by your new
vehicle warranty.
5-31
2003 - Sonoma OM

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 ADD mark, add a 50/50 mixture ofclean,
drinkable waterand DEX-COOL
®engine coolant at the
coolant recovery tank. SeeEngine Coolant on
page 5-25for 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 catchre and you or others
could be burned. Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
®coolant.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.
5-32
2003 - Sonoma OM

When the coolant in the coolant recovery tank is at the
ADD mark, start your vehicle.
If the overheat warning continues, there’s one more
thing you can try. You can add the proper 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.
5-33
2003 - Sonoma OM

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 until
itfirst stops. (Don’t press down while turning the
pressure cap.)
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, but now push
down as you turn it. Remove the pressure cap.
5-34
2003 - Sonoma OM

3. Fill the radiator with the proper DEX-COOL®
coolant mixture, up to the base of thefiller
neck. SeeEngine Coolant on page 5-25for more
information about the proper coolant mixture.4. Thenfill the coolant recovery tank to ADD mark.
5. Put the cap back on the coolant recovery tank,
but leave the radiator pressure cap off.
5-35
2003 - Sonoma OM

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
filler neck may be lower. If the level is lower, add
more of the proper DEX-COOL
®coolant mixture
through thefiller neck until the level reaches
the base of thefiller neck.8. Then replace the pressure cap. At any time during
this procedure if coolant begins toflow out of the
filler neck, reinstall the pressure cap. Be sure
the arrow on the pressure cap lines up like this.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.
5-36
2003 - Sonoma OM

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.
Power Steering Fluid
The power steering reservoir is located near the front of
the engine compartment on the driver’s side of the
vehicle.
When to Check Power Steering Fluid
It is not necessary to regularly check power steeringfluid
unless you suspect there is a leak in the system or
you hear an unusual noise. Afluid loss in this system
could indicate a problem. Have the system inspected
and repaired. SeeEngine Compartment Overview
on page 5-10for reservoir location.
How to Check Power Steering Fluid
Turn the key off, let the engine compartment cool down,
wipe the cap and the top of the reservoir clean, then
unscrew the cap and wipe the dipstick with a clean rag.
Replace the cap and completely tighten it. Then remove
the cap again and look at thefluid level on the dipstick.
For the 2200 L4 engine, thefluid level should be at
the C mark. For the VORTEC™4300 V6 engine, the
level should be between the ADD and FULL marks.
If necessary, add only enoughfluid to bring the level
up to the proper range.
5-37
2003 - Sonoma OM

What to Use
To determine what kind offluid to use, seePart D:
Recommended Fluids and Lubricants on page 6-33.
Always use the properfluid. Failure to use the proper
fluid can cause leaks and damage hoses and seals.
Windshield Washer Fluid
What to Use
When you need windshield washerfluid, be sure to read
the manufacturer’s instructions before use. If you will be
operating your vehicle in an area where the temperature
may fall below freezing, use afluid that has sufficient
protection against freezing. SeeEngine Compartment
Overview on page 5-10for reservoir location.
Adding Washer Fluid
Open the cap
with the washer
symbol on it.SeeEngine Compartment Overview on page 5-10for
more information on locationt. Add washerfluid until the
tank is full.
Notice:
When using concentrated washeruid, follow
the manufacturer’s instructions for adding
water.
Don’t mix water with ready-to-use washeruid.
Water can cause the solution to freeze and
damage your washeruid tank and other parts
of the washer system. Also, water doesn’t
clean as well as washeruid.
Fill your washeruid tank only three-quarters
full when it’s very cold. This allows for
expansion if freezing occurs, which could
damage the tank if it is completely full.
Don’t use engine coolant (antifreeze) in your
windshield washer. It can damage your
washer system and paint.
5-38
2003 - Sonoma OM