2002 GMC SIERRA coolant

5-10 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 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 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 ªOverheated Engine
Protection Operating Modeº in the Index for
information on driving to a safe place in an
emergency.

5-11
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 ªOverheated
Engine Protection Operating Modeº in the Index
for information on driving to a safe place in an
emergency.
If No Steam Is Coming From Your Engine
An overheat warning, along with a low coolant message,
can indicate a serious problem. See ªLow Coolant
Messageº in the Index.
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 ªDriving on Gradesº in the Index.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 (
)
or DRIVE (D).
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 and get everyone out of the vehicle until it cools
down. Also, see ªOverheated Engine Protection
Operating Modeº listed previously in this section.
You may decide not to lift the hood but to get service
help right away.

5-12
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 FanIf 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.

5-13
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 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 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
-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.

5-14 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 water and
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 ªEngine
Coolantº in the Index for more information.
If no coolant is visible in the surge tank, add coolant
as follows:
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.
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,
CAUTION: (Continued)

5-15
CAUTION: (Continued)
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.
So use the recommended coolant.
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.
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.

5-16
2. Then keep turning the pressure cap slowly, and
remove it.3. Then fill the coolant surge tank with the proper
mixture, to the FULL COLD mark.

5-17
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.
5. Then replace the
pressure cap. Be sure
the pressure cap
is hand
-tight and
fully seated.