2008 CADILLAC STS cooling

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
5-32

{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 could
require changing sooner, at 30,000 miles (50 000 km)
or 24 months, whichever occurs rst. Any repairs
would not be covered by the warranty. Always
use DEX-COOL
®(silicate-free) coolant in the 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 5-25for 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 the cooling system
can be dangerous. Plain water, or some other
liquid such as alcohol, can boil before the
proper coolant mixture will. The vehicle’s
coolant warning system is set for the proper
coolant mixture. With plain water or the wrong
mixture, the engine could get too hot but you
would not get the overheat warning. The
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. 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.
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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. SeeEngine Coolant on page 5-25for more
information.
5-36

{CAUTION:
Turning the Intercooler System pressure cap
when the engine and intercooler are hot can
allow steam and scalding liquids to blow out
and burn you badly. Never turn the Intercooler
System pressure cap, even a little, when the
engine and intercooler are hot.
{CAUTION:
Adding only plain water to the cooling system
can be dangerous. Plain water, or some other
liquid such as alcohol, can boil before the
proper coolant mixture will. The vehicle’s
coolant warning system is set for the proper
coolant mixture. With plain water or the wrong
mixture, the engine could get too hot but you
would not get the overheat warning. The
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.
{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.
5-37

Your dealer/retailer will know the kind of wheel
you need.
Each new wheel should have the same load-carrying
capacity, diameter, width, offset, and be mounted
the same way as the one it replaces.
If you need to replace any of your wheels, wheel bolts,
wheel nuts, or Tire Pressure Monitor System (TPMS)
sensors, replace them only with new GM original
equipment parts. This way, you will be sure to have the
right wheel, wheel bolts, wheel nuts, and TPMS
sensors for your vehicle.
{CAUTION:
Using the wrong replacement wheels, wheel
bolts, or wheel nuts on your vehicle can be
dangerous. It could affect the braking and
handling of your vehicle, make your tires lose
air and make you lose control. You could have
a collision in which you or others could be
injured. Always use the correct wheel, wheel
bolts, and wheel nuts for replacement.Notice:The wrong wheel can also cause problems
with bearing life, brake cooling, speedometer or
odometer calibration, headlamp aim, bumper height,
vehicle ground clearance, and tire or tire chain
clearance to the body and chassis.
SeeChanging a Flat Tire on page 5-96for more
information.
Used Replacement Wheels
{CAUTION:
Putting a used wheel on your vehicle is
dangerous. You cannot know how it has been
used or how far it has been driven. It could fail
suddenly and cause a crash. If you have to
replace a wheel, use a new GM original
equipment wheel.
5-81

The underhood fuse block is located in the front of the
engine compartment on the passenger’s side of the
vehicle. SeeEngine Compartment Overview on
page 5-11for more information on location and removal
procedure for the front compartment underhood
sights shields.
To access the fuses, push in the tabs located on each
side of the fuse block cover, then lift the cover off.
Notice:Spilling liquid on any electrical components
on your vehicle may damage it. Always keep the
covers on any electrical component.
Fuses JCase Usage
ABS MTRABS Module- ABS
Module-StabiliTrak
®
AFS Active Front Steering
BLWR Blower Motor
FAN 1 Cooling Fan-Low Speed
FAN 2 Cooling Fan-High Speed
LPDB 1 Driver Side Rear Fuse Block
LPDB 2 Driver Side Rear Fuse Block
RPDB 1 Passenger Side Rear Fuse Block
RPDB 2 Passenger Side Rear Fuse Block
SPARE Spare
SPARE Spare
STRTR Starter
Fuses Mini Usage
A/C CLTCH Air Conditioning Compressor Clutch
ABS ABS Module-StabiliTrak
®
ABS IGN Antilock Brake Controller
AUX OUTLET Rear Accessory Power Outlet
BRK VAC
PUMPBrake Vacuum Pump
CCP Climate Control Panel
CCP/RLY
COILSClimate Control Panel, Headlamp
Level Control, Active Cruise Control,
Relay Coils, Starter, Front Blower
ECM 1 Engine Control Module (ECM)
ECM/TCM
BATTECM, Transmission Control
Module (TCM)
ECM/TCM IGNECM, TCM, Instrument Panel
Cluster
EKM/I/P MDLEasy Key Module (EKM), Instrument
Panel Module (I/P MDL)
EVEN COILSEven Ignition Coils, Even Fuel
Injectors
FOG LAMP Front Fog Lamps
FRT PWR
OUTLETFront Accessory Power Outlet
FUEL COOL Fuel Cooling
HORN Horn
HTD
WASH/AQSHeated Headlamp Washer, Air
Quality Sensor
5-119