1999 BUICK CENTURY engine

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6-17
Passenger Compartment Air Filter
The passenger compartment
air filter is located
underneath your hood just
below the windshield wiper
arm on the passenger side
(underneath the air inlet
grille) of the vehicle.
The filter traps most of the pollen from the air entering
the air conditioning module. Like your engine's air
cleaner filter, it may need to be changed periodically.
For information on how often to change the passenger
compartment air filter, see ªMaintenance Scheduleº in
the Index.
To change the passenger compartment air filter, use the
following steps:
1. Turn off the ignition when the windshield wipers are
in the up position.2. Raise the hood.
3. Remove (disconnect) the windshield washer pump
hose from the fender rail and air inlet grille.
4. Reposition the hood weatherstrip from the
passenger's side of the vehicle (peel back halfway to
center).
5. Remove (disconnect) the air inlet grille retainers.
6. Remove (disconnect) the air inlet grille.
7. Remove (disconnect) the passenger compartment
air filter.
8. Then install the new air filter. For the type of filter to
use, see ªNormal Maintenance Replacement Partsº
in the Index.
9. Reposition the air inlet grille.
10. Replace the air inlet grille retainers.
11. Reposition the hood weatherstrip.
12. Reconnect the windshield washer pump hose to the
fender rail air inlet grille.
13. Close the hood.
14. Return the windshield wipers to the park position.

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6-18
Automatic Transaxle Fluid
When to Check and Change
A good time to check your automatic transaxle fluid
level is when the engine oil is changed.
Change both the fluid and filter every 50,000 miles
(83 000 km) if the vehicle is mainly driven under one or
more of these conditions:

In heavy city traffic where the outside temperature
regularly reaches 90F (32C) or higher.

In hilly or mountainous terrain.

When doing frequent trailer towing.

Uses such as found in taxi, police or delivery service.
If you do not use your vehicle under any of these
conditions, change the fluid and filter at 100,000 miles
(166 000 km).
See ªScheduled Maintenance Servicesº in the Index.
How to Check
Because this operation can be a little difficult, you
may choose to have this done at the dealership
service department.
If you do it yourself, be sure to follow all the instructions
here, or you could get a false reading on the dipstick.
NOTICE:
Too much or too little fluid can damage your
transaxle. Too much can mean that some of the
fluid could come out and fall on hot engine parts
or exhaust system parts, starting a fire. Be sure to
get an accurate reading if you check your
transaxle fluid.

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6-19
Wait at least 30 minutes before checking the transaxle
fluid level if you have been driving:

When outside temperatures are above 90F (32C).

At high speed for quite a while.

In heavy traffic
-- especially in hot weather.

While pulling a trailer.
To get the right reading, the fluid should be at normal
operating temperature, which is 180F to 200F
(82C to 93C).
Get the vehicle warmed up by driving about 15 miles
(24 km) when outside temperatures are above 50F
(10C). If it's colder than 50F (10C), you may
have to drive longer.
Checking the Fluid Level

Park your vehicle on a level place. Keep the
engine running.

With the parking brake applied, place the shift lever
in PARK (P).

With your foot on the brake pedal, move the shift
lever through each gear range, pausing for about
three seconds in each range. Then, position the shift
lever in PARK (P).

Let the engine run at idle for three to five minutes.Then, without shutting off the engine, follow these steps:
The automatic transaxle fluid dipstick is the red loop
located toward the rear of the engine.
1. Pull out the dipstick and wipe it with a clean rag or
paper towel.
2. Push it back in all the way, wait three seconds and
then pull it back out again.

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6-21
Radiator Pressure Cap
NOTICE:
Your radiator cap is a 15 psi (105 kPa)
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 overflow tube on the radiator
filler neck.
When you replace your radiator pressure cap, an
ACDelco
cap is recommended.
Thermostat
Engine coolant temperature is controlled by a thermostat
in the engine coolant system. The thermostat stops the
flow of coolant through the radiator until the coolant
reaches a preset temperature.
When you replace your thermostat, an ACDelco


thermostat is recommended.
Engine Coolant
The cooling system in your vehicle is filled with
DEX
-COOL
engine coolant. This coolant is designed
to remain in your vehicle for 5 years or 150,000 miles
(240 000 km), whichever occurs first, if you add only
DEX
-COOL
extended life coolant.
The following explains your cooling system and how to
add coolant when it is low. If you have a problem with
engine overheating or if you need to add coolant to your
radiator, see ªEngine Overheatingº in the Index.
A 50/50 mixture of clean, drinkable water and
DEX
-COOL
coolant will:

Give freezing protection down to
-34F (-37C).

Give boiling protection up to 265F (129C).

Protect against rust and corrosion.

Help keep the proper engine temperature.

Let the warning lights and gages work as
they should.

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6-22
NOTICE:
When adding coolant, it is important that you use
only DEX
-COOL
(silicate-free) coolant.
If coolant other than DEX-COOL is added to the
system, premature engine, heater core or
radiator corrosion may result. In addition, the
engine coolant will require change sooner
-- at
30,000 miles (50 000 km) or 24 months,
whichever occurs first. Damage caused by the use
of coolant other than DEX
-COOL
is not
covered by your new vehicle warranty.
What to Use
Use a mixture of one-half clean, drinkable water and
one
-half DEX-COOL
coolant which won't damage
aluminum parts. If you use this coolant mixture, you
don't need to add anything else.
CAUTION:
Adding only plain water to your cooling system
can be dangerous. Plain water, or some other
liquid like 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 wouldn't
get the overheat warning. Your engine could
catch fire and you or others could be burned. Use
a 50/50 mixture of clean, drinkable water and
DEX
-COOL
coolant.

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6-23
NOTICE:
If you use an improper coolant mixture, your
engine could overheat and be badly damaged.
The repair cost wouldn't 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 the proper coolant, you don't have to
add extra inhibitors or additives which claim to
improve the system. These can be harmful.
Checking Coolant
The vehicle must be on a
level surface. When your
engine is cold, the coolant
level should be at the
COLD mark or a little
higher. When your engine is
warm, the level should be
up to the HOT mark or a
little higher.
If this LOW COOLANT
light comes on and stays on,
it means you're low on
engine coolant.

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6-24
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.
If the coolant recovery tank is completely empty, add
coolant to the radiator. (See ªEngine Overheatingº in
the Index.)
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. Don't spill coolant on a hot engine.
Power Steering Fluid

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6-25 When to Check Power Steering Fluid
It is not necessary to regularly check power steering
fluid unless you suspect there is a leak in the system or
you hear an unusual noise. A fluid loss in this system
could indicate a problem. Have the system inspected
and repaired.
How to Check Power Steering Fluid
When the engine compartment is cool, wipe the cap and
the top of the reservoir clean, then unscrew the cap and
wipe the dipstick with a clean rag. Replace the cap and
completely tighten it. Then remove the cap again and
look at the fluid level on the dipstick.
When the engine
compartment is hot, the
level should be at the
H mark. When it's cold,
the level should be at the
C mark. If the fluid is at
the ADD mark, you should
add fluid.
What to Use
To determine what kind of fluid to use, see
ªRecommended Fluids and Lubricantsº in the Index.
Always use the proper fluid. Failure to use the proper
fluid can cause leaks and damage hoses and seals.