engine GMC YUKON XL 2002 Owners Manual

6-21Wait at least 30 minutes before checking the
transmission fluid level if you have been driving:

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

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 180  F
to 200  F (82  C to 93  C).
Get the vehicle warmed up by driving about 15 miles
(24 km) when outside temperatures are above 50  F
(10  C). If it's colder than 50  F (10  C), drive the
vehicle in THIRD (3) until the engine temperature gage
moves and then remains steady for 10 minutes.
A cold fluid check can be made after the vehicle has
been sitting for eight hours or more with the engine off,
but this is used only as a reference. Let the engine run at
idle for five minutes if outside temperatures are 50  F
(10  C) or more. If it's colder than 50  F (10  C), you
may have to idle the engine longer. Should the fluid
level be low during this cold check, you must check the
fluid hot before adding fluid. Checking the fluid hot will
give you a more accurate reading of the fluid level. Checking the Fluid Level
Prepare your vehicle as follows:

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 minutes or more.

6-22 Then, without shutting off the engine, follow these steps:
Your vehicle will have
either the transmission
dipstick handle labeled
ªTRANS/LOCKº or
will be labeled with
the graphic shown.
1. Flip the handle up and then 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.
3. Check both sides of the dipstick, and read the lower
level. The fluid level must be in the COLD area,
below the cross
- hatched area, for a cold check or in
the HOT area or cross
- hatched area for a hot check.
4. If the fluid level is in the acceptable range, push the
dipstick back in all the way; then flip the handle
down to lock the dipstick in place.

6-26 When the differential is cold, add enough lubricant
to raise the level to 1/2 inch (12 mm) below the filler
plug hole.
When the differential is at operating temperature
(warm), add enough lubricant to raise the level to
the bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See ªRecommended Fluids
and Lubricantsº in the Index.
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, see ªEngine Overheatingº in
the Index. A 50/50 mixture of clean, drinkable water and
DEX
- COOL 
coolant will:

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

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

Protect against rust and corrosion.

Help keep the proper engine temperature.

Let the warning lights and gages work as
they should.
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.

6-27What 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 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 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. 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.

6-28Checking Coolant The coolant surge tank
is located in the engine
compartment on the
passenger's side of
the vehicle.
See ªEngine Compartment Overviewº in the Index for
more information on location. 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 FILL
COLD mark.
If the LOW COOLANT
message comes on and stays
on, it means you're low on
engine coolant.
See ªLow Coolantº in the Index.

6-29Adding Coolant
If you need more coolant, add the proper DEX
- COOL

coolant mixture at the 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. Don't spill coolant on a hot engine.
When replacing the pressure cap, make sure it
is hand
- tight. Coolant Surge Tank Pressure Cap The coolant surge tank pressure cap must be fully
installed on the coolant surge tank. See ªEngine
Compartment Overviewº in the Index for more
information on location.
NOTICE: Your coolant surge tank pressure 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.

6-30Power Steering Fluid
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. See ªEngine Compartment Overviewº in the
Index for reservoir location. How to Check Power Steering Fluid Turn the key off, let the engine compartment cool down,
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.
The level should be at the FULL COLD mark.
If necessary, add only enough fluid to bring the level
up to the mark.
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.

6-31Windshield Washer Fluid What to Use When you need windshield washer fluid, be sure to read
the manufacturer's instructions before use. If you will be
operating your vehicle in an area where the temperature
may fall below freezing, use a fluid that has sufficient
protection against freezing. See ªEngine Compartment
Overviewº in the Index for reservoir location.
Adding Washer Fluid Your vehicle has a low washer fluid message that comes
on when the washer fluid is low. The message is
displayed for 15 seconds at the start of each ignition
cycle. When the LOW WASHER FLUID message is
displayed, you will need to add washer fluid to the
windshield washer fluid reservoir.
The windshield washer fluid
reservoir is located in the
engine compartment toward
the front of the vehicle on
the driver's side. Open the cap with the washer symbol on it. Add washer
fluid until the tank is full.
NOTICE:
When using concentrated washer fluid,
follow the manufacturer's instructions for
adding water.

Don't mix water with ready
- to
- use washer
fluid. Water can cause the solution to freeze
and damage your washer fluid tank and
other parts of the washer system. Also,
water doesn't clean as well as washer fluid.

Fill your washer fluid tank only
three
- quarters full when it's very cold. This
allows for expansion if freezing occurs,
which could damage the tank if it is
completely full.

Don't use engine coolant (antifreeze) in
your windshield washer. It can damage
your washer system and paint.

6-32Brakes Brake Fluid Your brake master
cylinder reservoir is
filled with DOT
- 3
brake fluid.
See ªEngine Compartment Overviewº in the Index for
the location of the reservoir. There are only two reasons why the brake fluid level in
the reservoir might go down. The first is that the brake
fluid goes down to an acceptable level during normal
brake lining wear. When new linings are put in, the fluid
level goes back up. The other reason is that fluid is
leaking out of the brake system. If it is, you should
have your brake system fixed, since a leak means that
sooner or later your brakes won't work well, or won't
work at all.
So, it isn't a good idea to ªtop offº your brake fluid.
Adding brake fluid won't correct a leak. If you add fluid
when your linings are worn, then you'll have too much
fluid when you get new brake linings. You should add
(or remove) brake fluid, as necessary, only when work is
done on the brake hydraulic system.

6-33CAUTION:If you have too much brake fluid, it can spill
on the engine. The fluid will burn if the engine
is hot enough. You or others could be burned,
and your vehicle could be damaged. Add brake
fluid only when work is done on the brake
hydraulic system. See ªChecking Brake Fluidº
in this section.
Refer to the Maintenance Schedule to determine when to
check your brake fluid. See ªPeriodic Maintenance
Inspectionsº in the Index. Checking Brake Fluid
You can check the brake fluid without taking off the cap.
Just look at the brake fluid reservoir. The fluid level
should be above MIN. If it isn't, have your brake system
checked to see if there is a leak.
After work is done on the brake hydraulic system,
make sure the level is above the MIN but not over the
MAX mark.