2007 BUICK LUCERNE Owner's Manual

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

How to Add Coolant to the Coolant
Recovery Tank
{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.
If you have not found a problem yet, but the
coolant level is not at the FULL COLD mark, add
a 50/50 mixture ofclean, drinkable waterand
DEX-COOL
®engine coolant at the coolant
recovery tank. SeeEngine Coolant on page 347
for more information.
{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 the coolant in the coolant recovery tank is
at the FULL COLD mark, start your vehicle.
356

If the overheat warning continues, there is one
more thing you can try. You can add the proper
coolant mixture directly to the radiator, but be sure
the cooling system is cool before you do it.
{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 radiator pressure cap — even
a little — they can come out at high
speed. Never turn the cap when the
cooling system, including the radiator
pressure cap, is hot. Wait for the cooling
system and radiator pressure cap to cool
if you ever have to turn the pressure cap.
How to Add Coolant to the Radiator
1. You can remove the radiator pressure cap
when the cooling system, including the
radiator 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.
2. Then keep turning the pressure cap. Remove
the pressure cap.
357

3. Remove the 3800 Series II V6 engine cover
shield to access the bleed valve.
3.1. Clean the area around the engine oil ll
tube and cap before removing. Twist
the oil ll tube, with cap attached,
counterclockwise and remove it.
3.2. Lift the engine cover shield at the front,
slide the catch tab out of the engine
bracket and remove the cover shield.
3.3. Put the oil ll tube, with cap attached, in
the valve cover oil ll hole until you are
ready to replace the cover shield.4. After the engine
cools, open the
coolant air bleed
valve. There is one
bleed valve. It is
located on the
thermostat housing.
5. Fill the radiator with the proper DEX-COOL
®
coolant mixture, up to the base of the ller
neck. SeeEngine Coolant on page 347
for more information about the proper coolant
mixture.
If you see a stream of coolant coming from an
air bleed valve, close the valve. Otherwise,
close the valve after the radiator is lled.
6. Rinse or wipe any spilled coolant from the
engine and the compartment.
358

7. Replace the 3800 Series II V6 engine cover
shield.
7.1. Remove the oil ll tube, with cap
attached, from the valve cover.
7.2. Insert the catch tab on the cover shield
under the bracket on the engine.
7.3. Place the hole in the cover shield over
the hole in the valve cover. Install oil ll
tube and cap by twisting clockwise.
8. Then ll the coolant recovery tank to the
FULL COLD mark.
9. Put the cap back on the coolant recovery tank,
but leave the radiator pressure cap off.10. Start the engine and let it run until you can
feel the upper radiator hose getting hot.
Watch out for the engine cooling fans.
11. By this time, the coolant level inside the
radiator ller neck may be lower. If the level is
lower, add more of the proper DEX-COOL
®
coolant mixture through the ller neck until the
level reaches the base of the ller neck.
12. Then replace the pressure cap. At any time
during this procedure if coolant begins to ow
out of the ller neck, reinstall the pressure
cap. Be sure the arrow on the pressure
cap lines up properly.
359

Cooling System (4.6L V8 Engine)
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 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.
360