2007 BUICK LUCERNE engine

What to Use
Use a mixture of one-half clean, drinkable water
and one-half DEX-COOL®coolant which will
not damage aluminum parts. If you use this coolant
mixture, you do not need to add anything else.
{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:If you use an improper coolant
mixture, your engine could overheat and be
badly damaged. The repair cost would not be
covered by your warranty. Too much water
in the mixture can freeze and crack the engine,
radiator, heater core, and other parts.
If you have to add coolant more than four times a
year, have your dealer check your cooling
system.
Notice:If you use extra inhibitors and/or
additives in your vehicle’s cooling system, you
could damage your vehicle. Use only the
proper mixture of the engine coolant listed in
this manual for the cooling system. See
Recommended Fluids and Lubricants on
page 452for more information.
348

Checking Coolant (3.8L V6 Engine)
This symbol is located
on the cap of the engine
coolant recovery tank.
The engine coolant recovery tank is located in the
engine compartment on the passenger’s side of
the vehicle. SeeEngine Compartment Overview on
page 334for more information on location.
The vehicle must be on a level surface. When
your engine is cold, the coolant level should be at
FULL COLD or a little higher. When your engine
is warm, the level should raise.
Adding Coolant
If you need more coolant, add the proper
DEX-COOL®coolant mixture at the coolant
recovery tank, but be careful not to spill it.
{CAUTION:
Turning the radiator pressure cap when the
engine and radiator are hot can allow steam
and scalding liquids to blow out and burn
you badly. With the coolant recovery tank,
you will almost never have to add coolant
at the radiator. Never turn the radiator
pressure cap — even a little — when
the engine and radiator are hot.
{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.
Occasionally check the coolant level in the radiator.
For information on how to add coolant to the
radiator, see Index. When replacing the pressure
cap, make sure to turn cap until it clicks.
349

Checking Coolant (4.6L V8 Engine)
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 334.{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.
350

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.
Occasionally check the coolant level in the
radiator. For information on how to add coolant to
the radiator, see Index. When replacing the
pressure cap, make sure to turn cap until it clicks.
Radiator Pressure Cap
Notice:The radiator cap on your vehicle is a
pressure-type cap and must be tightly
installed to prevent coolant loss and possible
engine damage from overheating. Be sure
the arrows on the cap line up with the overow
tube on the radiator ller neck.
SeeEngine Compartment Overview on page 334
for more information on location.
Engine Overheating
You will nd a warning light about a hot engine as
well as an engine coolant temperature gage on
your vehicle’s instrument panel cluster.
351

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 353for
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 353for information on driving to a
safe place in an emergency.
If No Steam Is Coming From Your
Engine
If you get an engine overheat warning 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.
352

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. Turn on your heater to full hot at the highest
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 vehicleuntil it
cools down.
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 337.
353

Cooling System (3.8L V6 Engine)
When you decide it is safe to lift the hood, here is
what you will see:
A. Radiator Pressure Cap
B. Coolant Recovery Tank
C. Electric Engine Cooling Fans{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 recovery tank is
boiling, do not do anything else until it cools down.
The vehicle should be parked on a level surface.
The coolant level should be at or above the
FULL COLD mark when the engine is cold. The
coolant level should be above the FULL COLD
mark under normal operating conditions. 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.
354

{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.
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.
355