CADILLAC STS 2007 1.G Owners Manual

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. See
Engine Compartment Overview on page 373for
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.
391

Checking Intercooler System Coolant
(4.4L V8 STS-V Engine Only)
SeeEngine Compartment Overview on page 373
for 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 visible in the intercooler ll neck.
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. See
Cooling System on page 396for instructions on
how to add coolant to the intercooler ll neck.
392

{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.
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 373for more
information on location.
Engine Overheating
There are two engine hot messages that could be
displayed in the Driver Information Center (DIC).
SeeDIC Warnings and Messages on page 264for
more information.
If the engine is overheating, then you will nd a
coolant temperature gage and a coolant warning
light on the instrument panel. SeeEngine
Coolant Temperature Gage on page 251and
Engine Coolant Temperature Warning Light on
page 251for more information.
393

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. 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 the vehicles
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 395for
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. See
Overheated Engine Protection Operating Mode
on page 395for information on driving to a
safe place in an emergency.
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 might 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.
394

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 the coolant warning light is not on or the coolant
temperature gage does not indicate the engine
is overheating, you can drive. Just to be safe, drive
slower for about 10 minutes. If the warnings do
not come back on, drive normally.
If the warnings continue and you have not stopped,
pull over, stop, and park the vehicle right away.
If there is still no sign of steam, idle the engine for
three minutes while parked. If the warnings are
still indicated, 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 might 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. An 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 380.
395

Cooling System
When you decide it is safe to lift the hood, this is
what you will see:
A. Engine Cooling Fans
B. Coolant Surge Tank and Pressure CapSome vehicles may have an engine driven fan, as
well as the electric pusher fans 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.
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.
3.6L V6 Engine shown, 4.6L V8 and 4.4L V8 STS-V
Engines similar
396

{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. SeeOverheated Engine Protection
Operating Mode on page 395for 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 could 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.
397

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 389for 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
CAUTION: (Continued)
CAUTION: (Continued)
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.
398

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. Do not spill
coolant on a hot engine.
If no coolant is visible in the surge tank, add
coolant as follows:
1. 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.
399

3. Fill the coolant surge tank with the proper
DEX-COOL®coolant mixture, to slightly
above the FULL COLD/FROID line on the
side of the coolant surge tank.
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. The
upper radiator hose is the largest of the
hoses which comes out of the radiator, on the
passenger side of the vehicle. Watch out
for the engine cooling fans.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/FROID line on the
side of the coolant surge tank.
5. Then replace the pressure cap. Be sure the
pressure cap is hand-tight and fully seated.
Start the engine and allow it to warm up.
How to Add Coolant to the Intercooler
System Fill Neck (4.4L V8 STS-V
Engine Only)
If you have not found a problem yet, turn the
engine off and allow it to cool down, then check to
see if coolant is visible within the horizontal
tube section of the ll neck. If coolant is not visible,
add a 50/50 mixture of clean, drinkable water
and DEX-COOL
®coolant to the ll neck. Be sure
the Intercooler System, including the Intercooler
System pressure cap, is cool before doing so. See
Engine Coolant on page 389for more information.
400