2003 GMC SIERRA Owner's Manual

Cooling System
When you decide it’s safe to lift the hood, here’s what
you’ll see:
A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine Fan
If the coolant inside the coolant surge tank is boiling,
don’t do anything else until it cools down. The vehicle
should be parked on a level surface.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. 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 enginefire, and you could be
burned. Get any leakfixed before you drive the
vehicle.
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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“Overheated Engine Protection Operating
Mode”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-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 occursfirst.
Damage caused by the use of coolant other
than DEX-COOL
®is not covered by your new vehicle
warranty.
How to Add Coolant to the Coolant
Surge Tank
If you haven’t found a problem yet, check to see if
coolant is visible in the surge tank. If coolant is visible
but the coolant level isn’t at or above the FULL
COLD mark, add a 50/50 mixture ofclean, drinkable
waterand DEX-COOL
®coolant at the coolant
surge tank, but be sure the cooling system, including
the coolant surge tank pressure cap, is cool before you
do it. SeeEngine Coolant on page 5-23for more
information.
{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 coolant
surge tank pressure cap -- even a little -- they
can come out at high speed. Never turn the
cap when the cooling system, including the
coolant surge tank pressure cap, is hot. Wait
for the cooling system and coolant surge tank
pressure cap to cool if you ever have to turn
the pressure cap.
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{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.
CAUTION: (Continued)
CAUTION: (Continued)
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
fire 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.
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1. Park the vehicle on a
level surface. You can
remove the coolant surge
tank pressure cap
when the cooling system,
including the coolant
surge tank pressure cap
and upper radiator
hose, is no longer hot.
Turn the pressure cap slowly counterclockwise
(left) 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 slowly, and
remove it.
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3. Thenfill the coolant surge tank with the proper
mixture, to the FULL COLD mark.4. With the coolant surge tank pressure cap off, start
the engine and let it run until you can feel the upper
radiator hose getting hot. Watch out for the
engine cooling fan.
By this time, the coolant level inside the coolant
surge tank may be lower. If the level is lower, add
more of the proper mixture to the coolant surge tank
until the level reaches the FULL COLD mark.
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5. Then replace the
pressure cap. Be sure
the pressure cap is
hand-tight and
fully seated.
Engine Fan Noise
Your 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 fan is spinning slower and the clutch is
not fully engaged. This improves fuel economy and
reduces fan noise. Under heavy vehicle loading, trailer
towing and/or high outside temperatures, the fan
speed increases as the clutch more fully 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 partially
disengages.
Power Steering Fluid
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 5-12for reservoir location.
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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.
The level should be at the FULL COLD mark. If
necessary, add only enoughfluid to bring the level up to
the mark.
What to Use
To determine what kind offluid to use, seePart D:
Recommended Fluids and Lubricants on page 6-15.
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 5-12for reservoir
location.
Adding Washer Fluid
Open the cap with the
washer symbol on it. Add
washerfluid until the
tank is full.
Notice:
•When using concentrated washerfluid, follow the
manufacturer’s instructions for adding water.
•Don’t mix water with ready-to-use washerfluid.
Water can cause the solution to freeze and
damage your washerfluid tank and other parts of
the washer system. Also, water doesn’t clean as
well as washerfluid.
•Fill your washerfluid 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.
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Brakes
Brake Fluid
Your brake master cylinder reservoir isfilled with DOT-3
brakefluid. SeeEngine Compartment Overview on
page 5-12for the location of the reservoir.
There are only two reasons why the brakefluid level in
the reservoir might go down. Thefirst is that the
brakefluid goes down to an acceptable level during
normal brake lining wear. When new linings are put in,
thefluid level goes back up. The other reason is
thatfluid is leaking out of the brake system. If it is, you
should have your brake systemfixed, since a leak
means that sooner or later your brakes won’t work well,
or won’t work at all.
So, it isn’t a good idea to“top off”your brakefluid.
Adding brakefluid won’t correct a leak. If you addfluid
when your linings are worn, then you’ll have too
muchfluid when you get new brake linings. You should
add (or remove) brakefluid, as necessary, only when
work is done on the brake hydraulic system.
{CAUTION:
If you have too much brakefluid, it can spill on
the engine. Thefluid will burn if the engine is
hot enough. You or others could be burned,
and your vehicle could be damaged. Add brake
fluid only when work is done on the brake
hydraulic system. See“Checking Brake Fluid”
in this section.
Refer to the Maintenance Schedule to determine when
to check your brakefluid. SeePart C: Periodic
Maintenance Inspections on page 6-14.
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