2003 PONTIAC GRAND PRIX engine

Engine Coolant
The cooling system in your vehicle is filled with
DEX-COOL@ engine coolant. This coolant is designed
to remain in your vehicle for
5 years or 150,000 miles
(240
000 km), whichever occurs first, if you add
only DEX-COOL@ extended life coolant.
The following explains your cooling system and how to
add coolant when it is low.
If you have a problem
with engine overheating or
if you need to add coolant to
your radiator, see Engine Overheating on page
5-33.
A 50/50 mixture of clean, drinkable water and
DEX-COOL@ engine coolant will:
Give freezing protection down to -34°F (-37°C).
Give boiling protection up to 265°F (129°C)
Protect against rust and corrosion.
Help keep the proper engine temperature.
Let the warning lights and gages work as
they should.
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.
What to Use
Use a mixture of one-half clean, drinkable water and
one-half DEX-COOL@ engine coolant which won’t
damage aluminum parts. If you use this coolant mixture,
you don’t need to add anything else.
1 ---.-.g only p n water to your c 3 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
CAUTION: (Continued)
I
5-30

Checking Coolant
coo It n ture. water or e
wrongmixture, 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: If you use an improper coolant mixture,
your engine could overheat and be badly damaged.
The repair cost wouldn’t be covered by your
warranty.
Too much water in the mixture can freeze
and crack the engine, radiator, heater core and
other parts.
If you have to add coolant more than four times a year,
have your dealer check your cooling system.
Notice: If you use the proper coolant, you don’t
have to add extra inhibitors or additives which claim
to improve the system. These can be harmful. The
coolant recovery tank is located in the engine
compartment toward the rear of the engine
on
the passenger’s side of the vehicle.
See Engine Compartment Overview on page
5-12 for
more information on location. The vehicle must be on
a level surface.
When your engine is
cold, the coolant level
should be
at the COLD
mark or a little higher.
When your engine is
warm, the level should
be up to the HOT mark
or a little higher.
When your engine is warm, the level should be up to
the HOT mark or a little higher.
5-31

Adding Coolant
If you need more coolant, add the proper DEX-COOL@
coolant mixture at the coolant recovery tank, but be
careful not to spill it.
If the coolant recovery tank is completely empty, add
coolant to the radiator. See Engine Overheating
on page 5-33.
Turning -.le radiator pressure cap when the engine and radiator are hot can allow steam and scalding liquids to blow out and burn
you badly.
With the coolant recovery tank,
you will almost never have to add coolant at
the radiator. Never turn the radiator pressure
cap
-- even a little -- when the engine and
radiator are hot. 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.
Occasionally check the coolant level in the radiator.
For information on how to add coolant to the radiator,
see Cooling System
on page 5-36.
5-32

Radiator Pressure Cap
Notice: Your radiator cap is a pressure-type cap
and must be tightly installed to prevent coolant
loss
and possible engine damage from overheating.
Be sure the arrows on the cap line up with the
overflow tube
on the radiator filler neck.
The radiator pressure cap is located in the front of the
engine compartment on the passenger’s side, near
the diagonal cross brace. See Engine Compartment
Overview on page
5-12 for more information on location.
Engine Overheating
You will find a coolant temperature gage and a warning
light concerning an overheated engine condition on
the instrument panel cluster. See Engine Coolant
Temperature Gage
on page 3-31 and Engine Coolant
Temperature Warning Light
on page 3-31.
Overheated Engine Protection
Operating Mode
This emergency operating mode allows your vehicle to
be driven tu
a safe place in an emergency situation.
If an overheated engine condition exists, an overheat
protection mode which alternates firing groups of
cylinders helps prevent engine damage. In this mode,
you will notice a significant
loss in power and engine
performance. The engine coolant temperature gage will
indicate an overheat condition exists. Driving extended
miles (km) and/or towing a trailer in the overheat
protection mode should be avoided.
Nofice: After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any
repair. The engine oil will be severely degraded.
Repair the cause of coolant
loss, change the oil
and reset the oil life system. See “Engine Oil”
ir
the Index.
5-33

If Steam Is Coming From Your Engine
Steam -m 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
CAUTION: (Continued) everyone away .rom the vehicle
UllLII it
coolsdown.
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.
5-34

If No Steam is Coming From Your
Engine
An overheat warning can indicate a serious problem.
If you get an engine overheat warning, 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.
If you get the overheat warning with no sign
of steam,
try this for a minute or
so:
1. In heavy traffic let the engine idle in NEUTRAL (N)
while stopped.
If it’s safe to do so, pull off the rozd,
shift to PARK
(P) or NEUTRAL (N) and let the
engine idle.
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, and you have not stopped,
pull over, stop, and park your vehicle right away.
If there’s still no sign of steam, you can idle the engine
for 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
“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.
2. Turn on your heater to full hot at the highest fan
speed and open the windows as necessary.
5-35

Cooling System
When you decide it’s safe to lift the hood, here’s what
you’ll see:
I
3100 V6 Engine
A. Coolant Recovery Tank
B. Electric Engine Cooling Fans
C. Radiator Pressure Cap
5-36

can start up even when the engine is not
running and can injure you. Keep hands,
clothing and tools away from any underhood
electric fan.
If the coolant inside the coolant recovery tank is boiling,
don’t do anything else until it cools down. The vehicle
should be parked on a level surface. When
the engine is cold,
the coolant level should be
at or above the
COLD
mark on the coolant
recovery tank.
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.
5-37