2003 CHEVROLET C/K radiator cap

5-20
Cooling System
When you decide it's safe to lift the hood, here's what
you'll see:
A. Engine Fan
B. Coolant Surge Tank
If your vehicle has a Caterpillar diesel engine, see the
Caterpillar

Diesel Engine Operation and Maintenance
Manual provided with your vehicle.If the coolant inside the coolant surge tank is boiling,
don't do anything else until it cools down. The vehicle
should be parked on a level surface.
The coolant level
should be at COLD
FILL or higher. If it
isn't, 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.

5-23
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:
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.
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.
1. Park the vehicle on a level surface. You can remove
the coolant surge tank pressure cap when the cooling
system, including the coolant surge tank pressure cap
and upper radiator hose, is no longer hot. Turn the
pressure cap slowly counterclockwise (left) about
one full turn. If you hear a hiss, wait for that to stop.
A hiss means there is still some pressure left.

5-25
4. With the coolant surge tank pressure cap off, start the
engine and let it run until you can feel the upper
radiator hose getting hot. Watch out for the engine
cooling fan.
By this time, the coolant level inside the coolant
surge tank may be lower. If the level is lower, add
more of the proper mixture to the coolant surge
tank until the level reaches slightly above the
FULL mark.
5. Then replace the
pressure cap. Be
sure the pressure
cap is hand
-tight
and fully seated.

6-37 Checking Coolant
The coolant surge tank is located in the engine
compartment on the driver's side of the vehicle.
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 COLD
FILL mark or higher.
If the low coolant light
comes on and stays on,
it means you're low on
engine coolant.
See ªLights, Low Coolant Warning Lightº in the Index
for further information.

7-19
(26) = Evaporative Control System Service
(if equipped): Check all fuel and vapor lines and hoses
for proper connections and correct routing (or every
24 months, whichever occurs first). Replace parts
as needed.
(28) = Replace spark plugs. Inspect wires for damage.
Check the wire boot and boot heat shield fit at spark
plugs and coil. Replace parts as needed.
(30) = Check the fuel tank, fuel cap and fuel lines for
damage which could cause leakage. Inspect fuel cap for
correct sealing ability and any indications of damage.
Check fuel cap gasket for even filler neck imprint.
Replace parts as needed.
(31) = Check EGR system as described in the
service manual. See ªService and Owner Publicationsº
in the Index.(32) = Inspect Electronic Vacuum Regulator Valve
(EVRV) filter for excessive contamination or plugging.
If needed, clean filter with solution of soap and water,
let dry and install.
(35) = Drain, flush and refill cooling system. See
ªRecommended Fluids and Lubricantsº in the Index for
what to use. Inspect hoses. Clean radiator, condenser,
pressure cap and neck. Pressure test cooling system and
pressure cap. For Caterpillar

diesel engines, always
refer to the Caterpillar Diesel Engine Operation &
Maintenance Manual for coolant recommendations and
change intervals.
(37) = Rear axle service: Change the lubricant. See
ªRecommended Fluids and Lubricantsº in the Index.
(38) = Front axle service: Re
-pack upper kingpin
roller bearing.

7-24
Automatic Transmission Shift Indicator Check
Check that the indicator points to the gear chosen.
Steering Check
Be alert for any changes in steering action, abnormal
front tire wear or steering wheel position. An inspection
or service is needed when the steering wheel is harder to
turn or has too much free play, or if there are strange
sounds when turning or parking.
Brake System Check
Be alert to illumination of the low air warning lamp or
for the tone alarm, or changes in braking action, such
as repeated pulling to one side, unusual sounds when
braking or increased brake pedal travel. Make sure air
brake system reservoirs are drained daily with full
system air pressure, and check system for leaks. Any
of these conditions could indicate the need for brake
system inspection and/or service.Engine Cooling System Service
Inspect the hoses and have them replaced if they are
cracked, swollen or deteriorated. Inspect all pipes,
fittings and clamps; replace as needed. Clean the outside
of the radiator and air conditioning condenser. To help
ensure proper operation, a pressure test of the cooling
system and pressure cap is recommended at least once
a year.
Exhaust System Check
Be alert for any changes in the sound of the exhaust
system or any smell of fumes. These are signs the
system may be leaking. Have it checked and/or repaired
at once. Refer to ªEngine Exhaustº and ªRunning Your
Engine While You're Parkedº in the Index.
Windshield Wipers and Washers Check
Check operation and condition of the wiper blades.
Check the flow of the washer spray.