2003 GMC SIERRA DENALI Owners Manual

If Steam Is Coming From Your Engine
I
1 Steam from an overheated engine can b
you badly, even if you just open the hood.
Stay away from the engine if you see or hear
steam coming from
it. Just turn it off and get
CAUTION: (Continued)
I
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 fire.
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 “Overheated Engine Protection Operating
Mode”
in the Index for information on driving
to a safe place in an emergency.
Notice: If your engine catches fire because you keep
driving with no coolant, your vehicle can be badly
damaged. The costly repairs would not be covered by
your warranty. See “Overheated Engine Protection
Operating Mode” in the Index for information on
driving to a safe place in an emergency.
5-28

If No Steam Is Coming From
Your Engine
An overheat warning, along with a low coolant message,
can indicate
a serious problem. See “Low Coolant”
under
DIC Warnings and Messages on page 3-53.
If you get an engine overheat warning with no low
coolant message, 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. See “Driving on Grades” under
Towing a Trailer on page 4-51.
If you get the overheat warning with no sign of steam,
try this for a minute or
so:
1. If your air conditioner is on, turn it off.
2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.
3. If you’re in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving
- AUTOMATIC OVERDRIVE (@ ).
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, 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 andget
everyone out
of the vehicle until it cools down. Also, see
Overheated Engine Protection Operating Mode listed
previously in this section.
You may decide not
to lift the hood but to get service
help right away.
5-29

Cooling System
When you decide it's safe to lift the hood, here's what
you'll see:
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.
A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine Fan The coolant level should
be at
or above the FULL
COLD mark. If it isn't,
you may have a leak at the
rn*:A.~~ z,=7j_ . %%A" %!!:..- pressure cap or in the
*^" radiator hoses, heater
hoses, radiator, water
pump or somewhere else
in the cooling system.
I
5-30

I
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 engine fire, and you could
be burned. Get any leak fixed 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 “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 occurs first.
Damage caused by the use of coolant other
than DEX-COOL@ is not covered by your new
vehicle warranty.
5-31

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 of clean, 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. See Engine
Coolant on
page 5-24 for more information.
/;1 CAUTIC I:
Steam and scaldin, ,iquids from a hot coa ....g
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.
CAUTION: (Continued) 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.
5-32

Adding ~.ly p.-.n water to your coa....g 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 fire and you or others could be
burned. Use a
50/50 mixture of clean, drinkable i i 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.
I
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.
5-33

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.
2. 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.
3. Then keep turning the pressure cap slowly, and
remove
it.
5-34

4. Then fill the coolant surge tank with the proper
mixture, to the FULL COLD mark. 5. 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.
5-35