2009 CADILLAC STS radiator

Cooling System
The cooling system allows the engine to maintain the
correct working temperature.
A. Electric Engine Cooling Fan(s) (Out of view)
B. Mechanical Engine Cooling Fan (If equipped)
(Out of view)
C. Coolant Surge Tank and Pressure Cap{CAUTION:
An electric engine cooling fan under the hood can
start up even when the engine is not running and
can cause injury. Keep hands, clothing, and tools
away from any underhood electric fan.
{CAUTION:
Heater and radiator hoses, and other engine parts,
can be very hot. Do not touch them. If you do, you
can be burned.
CAUTION: (Continued)
3.6L V6 Engine shown, 4.6L V8 and
4.4L V8 STS-V Engines similar
5-26

CAUTION: (Continued)
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.
Notice:Using coolant other than DEX-COOL
®can
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 vehicle warranty.
Always use DEX-COOL
®(silicate-free) coolant
in the vehicle.
Engine Coolant
The cooling system in the vehicle is lled with
DEX-COOL®engine coolant. This coolant is designed
to remain in the vehicle for ve years or 150,000 miles
(240 000 km), whichever occurs rst.
The following explains the cooling system and how to
check and add coolant when it is low. If there is a problem
with engine overheating, seeEngine Overheating on
page 5-34.
5-27

What to Use
{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.Use a 50/50 mixture of clean, drinkable water and
DEX-COOL
®coolant. If using this mixture, nothing else
needs to be added. This mixture:
Gives freezing protection down to−34°F (−37°C),
outside temperature.
Gives boiling protection up to 265°F (129°C),
engine temperature.
Protects against rust and corrosion.
Will not damage aluminum parts.
Helps keep the proper engine temperature.
Notice:If an improper coolant mixture is used,
the engine could overheat and be badly damaged.
The repair cost would not be covered by the vehicle
warranty. Too much water in the mixture can freeze
and crack the engine, radiator, heater core, and
other parts.
Notice:If extra inhibitors and/or additives are used
in the vehicle’s cooling system, the vehicle could
be damaged. Use only the proper mixture of
the engine coolant listed in this manual for the
cooling system. SeeRecommended Fluids and
Lubricants on page 6-13for more information.
5-28

{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:
An electric engine cooling fan under the hood can
start up even when the engine is not running and
can cause injury. Keep hands, clothing, and tools
away from any underhood electric fan.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.
5-31

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.
5-32

Maintenance Footnotes
(a)Visually inspect brake lines and hoses for proper
hook-up, binding, leaks, cracks, chafing, etc. Inspect disc
brake pads for wear and rotors for surface condition.
Inspect other brake parts, including calipers, parking
brake, etc.
(b)Visually inspect front and rear suspension and
steering system for damaged, loose, or missing parts or
signs of wear. Inspect power steering lines and hoses
for proper hook-up, binding, leaks, cracks, chafing, etc.
(c)Visually inspect hoses and have them replaced if they
are cracked, swollen, or deteriorated. Inspect all pipes,
fittings, and clamps; replace with genuine parts as
needed. To help ensure proper operation, a pressure test
of the cooling system and pressure cap and cleaning the
outside of the radiator and air conditioning condenser is
recommended at least once a year.
(d)Inspect wiper blades for wear, cracking, or
contamination. Clean the windshield and wiper blades,
if contaminated. Replace wiper blades that are worn
or damaged. See Windshield Wiper Blade Replacement
on page 5-52 and Windshield and Wiper Blades on
page 5-120 for more information.(e)Make sure the safety belt reminder light and safety
belt assemblies are working properly. Look for any other
loose or damaged safety belt system parts. If you see
anything that might keep a safety belt system from doing
its job, have it repaired. Have any torn or frayed safety
belts replaced. Also see Checking the Restraint Systems
on page 1-66.
(f)Lubricate all key lock cylinders. Lubricate all
hinges and latches, including those for the hood, rear
compartment, glove box door, and console door. More
frequent lubrication may be required when exposed to a
corrosive environment. Applying silicone grease on
weatherstrips with a clean cloth will make them last
longer, seal better, and not stick or squeak.
(g)If driving regularly under dusty conditions, the filter
may require replacement more often.
(h)Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as limousine service.
Uses such as high performance operation.
6-8

(i)If using DOT-4 brake fluid only: Drain, flush, and refill
brake hydraulic system at a regular maintenance service
every two years. This service can be complex; you should
have your dealer/retailer perform this service. See Brakes
on page 5-39.
(j)Drain, flush, and refill cooling system. This service can
be complex; you should have your dealer/retailer perform
this service. See Engine Coolant on page 5-27 for what to
use. Inspect hoses. Clean radiator, condenser, pressure
cap, and filler neck. Pressure test the cooling system and
pressure cap.
(k)A fluid loss in any vehicle system could indicate a
problem. Have the system inspected and repaired
and the fluid level checked. Add fluid if needed.
(l)Drain, flush, and refill intercooler system. This service
can be complex; you should have your dealer/retailer
perform this service. See Engine Coolant on page 5-27.
(m)If driving regularly under dusty conditions, inspect
the filter at each engine oil change.
(n)Visually inspect belt for fraying, excessive cracks, or
obvious damage. Replace belt if necessary.(p)If the vehicle has the 3.6L V6 (VIN Code V) engine,
replace the engine air cleaner filter every 40,000 miles
(64 000 km).
(q)Check vent hose at transfer case for kinks and proper
installation. Check to be sure vent hose is unobstructed,
clear, and free of debris. During any maintenance, if a
power washer is used to clean mud and dirt from the
underbody, care should be taken to not directly spray the
transfer case output seals. High pressure water can
overcome the seals and contaminate the transfer case
fluid. Contaminated fluid will decrease the life of the
transfer case and should be replaced.
(r)Change transfer case fluid if the vehicle is mainly
driven under one or more of these conditions:
In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as high performance operation or taxi,
police, or delivery service.
6-9