2006 CADILLAC STS engine coolant

Checking Coolant
The coolant surge tank and pressure cap are located on
the driver’s side of the vehicle, toward the rear of the
engine compartment. SeeEngine Compartment
Overview on page 5-12for more information on location.
{CAUTION:
Turning the surge tank pressure cap when the
engine and radiator are hot can allow steam
and scalding liquids to blow out and burn you
badly. Never turn the surge tank pressure
cap — even a little — when the engine and
radiator are hot.
The vehicle must be on a level surface. When your
engine is cold, the coolant level should be at the FULL
COLD/FROID line on the side of the surge tank.
Follow the arrow from the top of the tank down the side
to the horizontal mark.
If the CHECK COOLANT LEVEL message in the Driver
Information Center (DIC) comes on and stays on, it
means you are low on engine coolant. SeeDIC
Warnings and Messages on page 3-79for more
information.
5-28

Checking Intercooler System Coolant
(4.4L V8 STS-V Engine Only)
SeeEngine Compartment Overview on page 5-12for
the location of the intercooler system pressure cap.
Notice:This vehicle has a specic coolant ll
procedure. Failure to follow this procedure could
cause your engine to overheat and be severely
damaged.
Park the vehicle on a level surface and turn off the
engine. When the engine is cold, the coolant level
should be at or above the FULL COLD line. The
FULL COLD line has an arrow pointing to it.
Adding Coolant
If you need more coolant, add the proper DEX-COOL®
coolant mixture at the intercooler ll neck, but only
when the engine is cool. SeeCooling System on
page 5-32for instructions on how to add coolant to
the intercooler ll neck.
{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. Do not spill coolant on a hot engine.
When replacing a pressure cap, make sure it is
hand-tight and fully seated.
5-29

Coolant Surge Tank Pressure Cap
Notice:If the pressure cap is not tightly installed,
coolant loss and possible engine damage may
occur. Be sure the cap is properly and tightly
secured.
The coolant surge tank pressure cap must be fully
installed on the coolant surge tank. SeeEngine
Compartment Overview on page 5-12for more
information on location.
Engine Overheating
You will nd an ENGINE COOLANT HOT IDLE
ENGINE, an ENGINE OVERHEATED STOP ENGINE
and a CHECK COOLANT LEVEL message displayed in
the Driver Information Center (DIC). SeeDIC Warnings
and Messages on page 3-79for more information.
There is also a coolant temperature gage and a coolant
warning light on the instrument panel. SeeEngine
Coolant Temperature Gage on page 3-67andEngine
Coolant Temperature Warning Light on page 3-66
for more information.
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 re. You
or others could be badly burned. Stop your
engine if it overheats, and get out of the vehicle
until the engine is cool.
SeeOverheated Engine Protection Operating
Mode on page 5-31for information on driving to
a safe place in an emergency.
Notice:If your engine catches re because you keep
driving with no coolant, your vehicle can be badly
damaged. The costly repairs would not be covered by
your warranty. SeeOverheated Engine Protection
Operating Mode on page 5-31for information on
driving to a safe place in an emergency.
5-30

If No Steam Is Coming From
Your Engine
An overheat warning, along with a CHECK COOLANT
LEVEL message, can indicate a serious problem.
If you get an engine overheat warning with no CHECK
COOLANT LEVEL 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.
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 is safe to do so, pull off the road,
shift to PARK (P) or NEUTRAL (N) and let the
engine idle.
2. Set the climate controls to the highest heat setting
and fan speed and open the windows, as
necessary.
If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning does not 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 is still no sign of steam, you can idle the engine
for three minutes while you are 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” later in this section.
You may decide not to lift the hood but to get service
help right away.
Overheated Engine Protection
Operating Mode
This operating mode allows your vehicle to be driven to
a safe place in an emergency. Should an overheated
engine condition exist, an overheat protection mode
which alternates ring groups of cylinders helps prevent
engine damage. In this mode, you will notice a loss
in power and engine performance. A low coolant and/or
engine overheat warning will indicate that an overheat
condition exists. Driving extended miles (km) and/or
towing a trailer in the overheat protection mode should
be avoided.
Notice: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 and change the oil. SeeEngine
Oil on page 5-18.
5-31

Cooling System
When you decide it is safe to lift the hood, here is what
you will see:
A. Electric Engine Cooling Fans
B. Coolant Surge Tank and Pressure Cap
Some vehicles may be equipped with an engine
driven fan, as well as the electric pusher fans (A)
which are located behind the vehicle’s grille.{CAUTION:
An electric engine cooling fan under the hood
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 surge tank is boiling
do not do anything else until it cools down. The vehicle
should be parked on a level surface.
3.6L V6 Engine shown, 4.6L V8 and 4.4L V8 STS-V
Engines similar
5-32

When the engine is cold, the coolant level should be at
or slightly above the FULL COLD/FROID line on the
side of the coolant surge tank. If it is not, 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. Do not touch them.
If you do, you can be burned.
Do not run the engine if there is a leak. If you
run the engine, it could lose all coolant. That
could cause an engine re, and you could be
burned. Get any leak xed before you drive the
vehicle.If there seems to be no leak, with the engine on, check
to see if the electric engine cooling fans are running.
If the engine is overheating, both fans should be
running. If they are not, your vehicle needs service.
Notice:Engine damage from running your engine
without coolant is not covered by your warranty. See
Overheated Engine Protection Operating Mode on
page 5-31for information on driving to a safe place
in an emergency.
Notice:Using coolant other than DEX-COOL®may
cause premature engine, heater core or radiator
corrosion. In addition, the engine coolant may
require changing sooner, at 30,000 miles (50 000 km)
or 24 months, whichever occurs rst. Any repairs
would not be covered by your warranty. Always use
DEX-COOL
®(silicate-free) coolant in your vehicle.
5-33

How to Add Coolant to the Coolant
Surge Tank
If you have not found a problem yet, check to see if
coolant is visible in the surge tank. If coolant is visible
but the coolant level is not at the FULL COLD/FROID
line on the side of the coolant surge tank, 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. SeeEngine
Coolant on page 5-26for 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.
{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 would not get the overheat warning.
Your engine could catch re 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.
5-34

{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. Do not spill coolant on a hot engine.
If no coolant is visible in the surge tank, add coolant
as follows:
1. 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 about one-quarter of a 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.
5-35