2006 CADILLAC DTS PROFESSIONAL engine

Checking Coolant
The engine coolant surge
tank is located toward the
rear of the engine
compartment on the
passenger’s side of
the vehicle.
For more information on location, seeEngine
Compartment Overview on page 5-12.{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 mark, located on the side of the surge tank
that faces the engine.
5-24

Adding Coolant
If you need more coolant, add the proper DEX-COOL®
coolant mixture at the coolant surge tank, but only
when the engine is cool.
{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 the pressure cap, make sure to turn the
cap until it clicks.
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.
SeeEngine Compartment Overview on page 5-12for
more information on location.
Engine Overheating
You will nd an ENGINE OVERHEATED IDLE ENGINE
message or an ENGINE OVERHEATED STOP
ENGINE message displayed in the Driver Information
Center (DIC). SeeDIC Warnings and Messages
on page 3-76for more information. You will also
hear a chime.
There is also an engine temperature warning light
and/or gage on the instrument panel cluster. SeeEngine
Coolant Temperature Warning Light on page 3-65and
Engine Coolant Temperature Gage on page 3-65.
5-25

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 5-27for 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 5-27for information on
driving to a safe place in an emergency.If No Steam Is Coming From
Your Engine
An overheat warning, along with a low coolant message,
can indicate a serious problem.
If you get an engine overheat warning with no low
coolant 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.
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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 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, pull over, stop, and park your
vehicle right away.
If there is still no sign of steam, 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
If an overheated engine condition exists and the
message ENGINE OVERHEATED STOP ENGINE is
displayed, 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. This operating mode allows your
vehicle to be driven to a safe place in an emergency.
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, change the oil and
reset the oil life system. SeeEngine Oil on
page 5-13.
5-27

Cooling System
When you decide it is safe to lift the hood, here is what you will see:
A. Coolant Surge Tank with Pressure Cap B. Electric Engine Cooling Fans4.6L L37 Engine shown, 4.6L LD8 Engine similar
5-28

{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.
{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 5-27for 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.
5-29

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 level is not at the FULL COLD mark located
on the side of the surge tank, add enough of a
50/50 mixture of clean, drinkable water and
DEX-COOL
®coolant at the coolant surge tank to
bring the level to the FULL COLD mark, but be sure
the cooling system, including the coolant surge
tank pressure cap (if equipped), is cool before you
do it. SeeEngine Coolant on page 5-22for more
information.If no coolant is visible in the surge tank, add coolant as
follows:
{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.
5-30

{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.
{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.
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. If
you hear a hiss, wait for that to stop. A hiss means
there is still some pressure left.
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