1999 GMC SIERRA radiator cap

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Cooling System (Gasoline Engine)
When you decide it's safe to lift the hood, here's what
you'll see:
A. Coolant Recovery Tank
B. Radiator Pressure Cap
C. Engine Fan(s)
CAUTION:
If your vehicle has air conditioning, the auxiliary
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,
don't do anything else until it cools down.

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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.

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5-16 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 until it first
stops. (Don't press down while turning the
pressure cap.)
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, but now push
down as you turn it. Remove the pressure cap.

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3. Fill the radiator with the proper DEX-COOL

coolant mixture, up to the base of the filler neck.
(See ªEngine Coolantº in the Index for more
information about the proper coolant mixture.)
4. Then fill the coolant recovery tank to the
COLD mark.
5. Put the cap back on the coolant recovery tank, but
leave the radiator pressure cap off.

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6. Start the engine and let it run until you can feel the
upper radiator hose getting hot. Watch out for the
engine cooling fan(s).
7. By this time, the coolant level inside the radiator
filler neck may be lower. If the level is lower, add
more of the proper DEX
-COOL
coolant mixture
through the filler neck until the level reaches the
base of the filler neck.
8. Then replace the pressure cap. At any time during
this procedure if coolant begins to flow out of the
filler neck, reinstall the pressure cap. Be sure the
arrows on the pressure cap line up like this.

6-
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6-1
Section 6 Service and Appearance Care
Here you will find information about the care of your vehicle. This section begins with service and fuel information,
and then it shows how to check important fluid and lubricant levels. There is also technical information about your
vehicle, and a part devoted to its appearance care.
6
-2 Service
6
-3 Fuel (Gasoline Engine)
6
-5 Fuels in Foreign Countries (Gasoline Engines)
6
-5 Filling Your Tank (Gasoline Engine)
6
-8 Filling a Portable Fuel Container
6
-8 Checking Things Under the Hood
6
-12 Noise Control System
6
-13 Engine Oil (Gasoline Engine)
6
-17 Engine Air Cleaner/Filter (Gasoline Engines)
6
-20 Automatic Transmission Fluid
6
-23 Manual Transmission Fluid
6
-24 Hydraulic Clutch
6
-25 Rear Axle
6
-26 Four-Wheel Drive
6
-27 Radiator Pressure Cap (Gasoline Engine)
6
-28 Thermostat
6
-28 Engine Coolant6
-32 Power Steering Fluid
6
-33 Windshield Washer Fluid
6
-34 Brakes
6
-38 Battery
6
-39 Bulb Replacement
6
-49 Windshield Wiper Blade Replacement
6
-50 Tires
6
-61 Appearance Care
6
-61 Cleaning the Inside of Your Vehicle
6
-65 Cleaning the Outside of Your Vehicle
6
-68 GM Vehicle Care/Appearance Materials
6
-69 Vehicle Identification Number (VIN)
6
-69 Electrical System
6
-75 Replacement Bulbs
6
-76 Capacities and Specifications
6
-78 Air Conditioning Refrigerants
6
-78 Normal Maintenance Replacement Parts

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ªVORTECº 5000 and 5700 V8 Engine
ªVORTECº 5700 engine shown, locations for other engines similar. When you lift up the hood you'll see:
A. Battery
B. Engine Air Cleaner/Filter
C. Radiator Cap
D. Coolant Recovery Tank
E. Air Filter Restriction Indicator
F. Engine Oil DipstickG. Automatic Transmission
Dipstick (If Equipped)
H. Fan
I. Power Steering Fluid Reservoir
J. Engine Oil Fill
K. Brake Fluid ReservoirL. Clutch Fluid Reservoir
(If Equipped)
M. Windshield Washer Fluid
Reservoir
N. Fuse/Relay Center

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ªVORTECº 7400 V8 Engine
A. Battery
B. Coolant Recovery Tank
C. Engine Air Cleaner/Filter
D. Radiator Cap
E. Air Filter Restriction Indicator
F. Engine Oil DipstickG. Automatic Transmission
Dipstick (If Equipped)
H. Engine Oil Fill
I. Fan
J. Power Steering Fluid Reservoir
K. Brake Fluid ReservoirL. Clutch Fluid Reservoir
(If Equipped)
M. Windshield Washer
Fluid Reservoir
N. Fuse/Relay Center