1999 GMC C-SERIES Owners Manual

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6-27
CAUTION:
Turning the radiator pressure cap (on a gasoline
engine) or the surge tank cap (on a diesel engine)
when the engine and radiator are hot can allow
steam and scalding liquids to blow out and burn
you badly. With the coolant recovery system, you
will almost never have to add coolant at the
radiator. Never turn the radiator pressure cap
or the surge tank pressure cap
-- even a
little
-- when the engine and radiator are hot.
Add coolant mixture at the recovery tank or the surge
tank, but be careful not to spill it.
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.
Some conditions, such as trapped air in the cooling
system, can affect the coolant level in the radiator. If you
need to add coolant to the radiator, follow the steps
listed under ªHow to Add Coolant to the Radiator.º
See ªEngine Overheatingº in the Index.
Engine Coolant
(Caterpillar
Diesel Engine)
If your vehicle has a Caterpillar diesel engine, see the
Caterpillar
Operation & Maintenance Manual provided
with your vehicle to find out what to add, also when and
how to service your cooling system.
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6-28
Power Steering Fluid
See your Maintenance Schedule for when to check your
power steering fluid.
How To Check Power Steering Fluid
Check your power steering fluid only when the engine is
warm. If the engine isn't warm, you probably won't get
an accurate reading.
Vehicles with diesel engines
have a sight glass. If you
can see fluid in the glass,
you have enough.Other models have a cap with a dipstick. If you have
one, unscrew the cap and check the dipstick. It should be
between ADD and FULL (if the engine is warm).
If you need to add some, put in only enough of the
correct fluid to bring the level up to the FULL mark (if
you have the dipstick) or so you can see fluid in the
glass, if you have a sight glass.
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6-29 What to Use
To determine what kind of fluid to use, see
ªRecommended Fluids and Lubricantsº in the Index.
NOTICE:
When adding power steering fluid or making a
complete fluid change, always use the proper
fluid. Failure to use the proper fluid can cause
leaks and damage hoses and seals.
If your power steering fluid level is low, this can
cause the PRIMARY BRAKE or AUX BRAKE
warning lights to come on. If either light remains
on after you have added power steering fluid to
the proper level, then shut off the engine for
10 seconds. This should reset the brake warning
lights. If one or both lights stay on, though,
then see ªHydraulic Brake Warning Lightsº in
the Index.
Windshield 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.
Adding Washer Fluid
Open the cap labeled WASHER FLUID ONLY.
Add washer fluid until the tank is full.
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6-30
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.
Brakes
Brake Fluid
If your vehicle has
hydraulic brakes, there's
a brake master cylinder.
The brake master cylinder
reservoir is here. Refer to
the Maintenance Schedule
to determine when to check
your brake fluid.
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6-31
CAUTION:
Don't add brake fluid before you check the level.
If you do, you could get too much brake fluid.
Brake fluid could spill on the hot engine and it
can catch fire. You could be burned and your
vehicle could be damaged.
Checking Brake Fluid
Apply the brake pedal several times with the ignition
off. Then clean one of the reservoir caps and the area
around the cap, and remove it. The fluid level should be
even with the bottom ring of the filler opening.
If it's low, add enough fluid
to fill the reservoir to the
proper level.
What to Add
Use the proper fluid listed in your Maintenance
Schedule. Use new brake fluid from a sealed
container only.
Always clean the brake fluid reservoir cap and the area
around the cap before removing it. This will help keep
dirt from entering the reservoir.
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6-32
CAUTION:
With the wrong kind of fluid in your brake
system, your brakes may not work well, or they
may not even work at all. This could cause a
crash. Always use the proper brake fluid.
NOTICE:

Using the wrong fluid can badly damage
brake system parts. For example, just a few
drops of mineral
-based oil, such as engine
oil, in your brake system can damage brake
system parts so badly that they'll have to be
replaced. Don't let someone put in the
wrong kind of fluid, and don't use DOT
-5
silicone brake fluid.
NOTICE: (Continued)
NOTICE: (Continued)

If you spill brake fluid on your vehicle's
painted surfaces, the paint finish can be
damaged. Be careful not to spill brake fluid
on your vehicle. If you do, wash it off
immediately. See ªAppearance Careº in
the Index.
Four-Wheel Disc Brakes (Hydraulic Only)
Your vehicle has four-wheel disc brakes.
Some driving conditions or climates may cause a brake
squeal when the brakes are first applied or lightly
applied. This does not mean something is wrong with
your brakes.
Brake linings should always be replaced as complete
axle sets.
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6-33 Four-Wheel and Six-Wheel Drum Brakes
(Air Only)
The brake drums should be removed and inspected each
time the tires are removed for rotation or changing.
When you have the front brakes replaced, have the rear
brakes inspected, too.
Brake linings should always be replaced as complete
axle sets.
Brake Pedal Travel
See your dealer if the brake pedal does not return to
normal height, or if there is a rapid increase in pedal
travel. This could be a sign of brake trouble.
Brake Adjustment
Every time you make a brake stop, your brakes adjust
for wear.
Air Brake Systems (If Equipped)
If you have air brakes, it is important to get rid of
moisture in the system. Moisture will damage your
system if it isn't removed daily.There are two ways to do this. One is automatic if your
air
-brake vehicle has the optional moisture ejector. If
your vehicle doesn't have that option, however, you
must drain the air reservoirs every day.
Drain them at full system
pressure. To be sure you're
at full pressure, check
your air pressure gage.
It should read at least
100 psi (692 kPa).
Moisture Ejector (Option)
If you have air brakes with a moisture ejector, the valve
automatically ejects moisture from the reserve tank
when the air compressor cycles.
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6-34 Air Dryer (Option)
If your vehicle has air brakes, it may have an air dryer.
This collects and removes dirt, moisture or other foreign
matter from the air prior to entering the brake system. It
is mounted on the left frame rail.
If your dryer is a
Bendix
-Westinghouse, it
has a filter that you need to
change at intervals. See
your Maintenance Schedule
for more about servicing
this filter.
Alcohol Injector (Option)
If your vehicle has air brakes, it may have an alcohol
injector. It is on the frame or crossmember at the right
front corner of the vehicle.
The alcohol injector helps prevent moisture in the air
brake system from freezing. Use it only in cold weather,
32
F (0
C) or below.
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