1999 CHEVROLET SILVERADO engine overheat

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5-33
If You're Stuck: In Sand, Mud,
Ice or Snow
In order to free your vehicle when it is stuck, you will
need to spin the wheels, but you don't want to spin your
wheels too fast. The method known as ªrockingº can
help you get out when you're stuck, but you must
use caution.
CAUTION:
If you let your tires spin at high speed, they can
explode, and you or others could be injured. And,
the transmission or other parts of the vehicle can
overheat. That could cause an engine
compartment fire or other damage. When you're
stuck, spin the wheels as little as possible. Don't
spin the wheels above 35 mph (55 km/h) as shown
on the speedometer.
NOTICE:
Spinning your wheels can destroy parts of your
vehicle as well as the tires. If you spin the wheels
too fast while shifting your transmission back
and forth, you can destroy your transmission.
For information about using tire chains on your vehicle,
see ªTire Chainsº in the Index.
Rocking Your Vehicle To Get It Out
First, turn your steering wheel left and right. That will clear
the area around your front wheels. If you have a four
-wheel
drive vehicle, shift into 4HI. Then shift back and forth
between REVERSE (R) and a forward gear (or with a
manual transmission, between FIRST (1) or SECOND (2)
and REVERSE (R)), spinning the wheels as little as possible.
Release the accelerator pedal while you shift, and press
lightly on the accelerator pedal when the transmission is in
gear. By slowly spinning your wheels in the forward and
reverse directions, you will cause a rocking motion that may
free your vehicle. If that doesn't get you out after a few tries,
you may need to be towed out. Or, you can use your recovery
hooks if your vehicle has them. If you do need to be towed
out, see ªTowing Your Vehicleº in the Index.

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6-28
Coolant Surge Tank Pressure Cap
(Gasoline Engine)
The coolant surge tank pressure cap must be fully
installed on the coolant surge tank.
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.
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.

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6-29
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
-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.
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.

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6-30 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.
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.

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9-4
Driving (Continued)
Through Water 4-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wet Roads 4-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Winter 4-40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
With a Trailer 4-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drunken Driving 4-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Easy Entry Seat 1-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Equipment, Adding 2-17, 3-26, 6-70 . . . . . . . . . . .
Electrical System 6-64 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrochromic Day/Night Rearview Mirror 2-56 . . . . . . . . . .
Engine 6-10, 6-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant 6-29, 6-75, 7-25 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Heater 2-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Level Check 7-18 . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Temperature Gage 2-75 . . . . . . . . . . . . . . . . . . . . .
Cooling System Capacity 6-75 . . . . . . . . . . . . . . . . . . . . . . .
Exhaust 2-39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuse Block 6-69 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Identification 6-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Level Check 7-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overheating 5-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Running While Parked 2-40 . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications 6-74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting Your 2-16, 2-18 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Underhood Electrical Center 6-69 . . . . . . . . . . . . . . . . . . . .
Engine Fan Noise 5-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Oil 6-12, 7-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adding 6-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additives 6-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking 6-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oil Life Monitor 6
-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure Gage 2-79 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Used 6-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
When to Change 6-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Overheated Message 2-85 . . . . . . . . . . . . . . . . . . . . . .
Exhaust, Engine 2-39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fabric Cleaning 6-54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fan Control, Climate Control System 3-2, 3-3 . . . . . . . . . . . .
Filling a Portable Fuel Container 6-8 . . . . . . . . . . . . . . . . . . . .
Filling Your Tank 6-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter
Engine Air Cleaner 6
-16, 6-77 . . . . . . . . . . . . . . . . . . . . . . .
Oil 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Passenger Compartment Air 3-5, 6-18, 6-77 . . . . . . . . . . .
Finish Care 6-58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Finish Damage 6-60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flashers, Hazard Warning 5-2 . . . . . . . . . . . . . . . . . . . . . . . . .
Flat Tire, Changing 5-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid Capacities 6-75 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluids and Lubricants 7-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fog Lamps 2-53 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Foreign Countries, Fuel 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Four-Wheel Drive 2-27, 6-26 . . . . . . . . . . . . . . . . . . . . . . . . .
French Language Manual ii. . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Axle 6
-27, 7-26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Axle Locking Feature 2-27 . . . . . . . . . . . . . . . . . . . . . . .
Front Axle Reserve Capacity 4-49 . . . . . . . . . . . . . . . . . . . . . .
Front Sidemarker Lamp Bulb Replacement 6-40 . . . . . . . . . . .
Front Towing 5-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Turn Signal Lamp Bulb Replacement 6-40 . . . . . . . . . .

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9-7
Maintenance, Normal Replacement Parts 6-77 . . . . . . . . . . .
Maintenance Record 7-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance Schedule 7-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Owner Checks and Services 7-18 . . . . . . . . . . . . . . . . . . . . .
Periodic Maintenance Inspections 7-23 . . . . . . . . . . . . . . . .
Recommended Fluids and Lubricants 7-25 . . . . . . . . . . . . .
Scheduled Maintenance Services 7-4 . . . . . . . . . . . . . . . . . .
Maintenance Services 7-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance, Underbody 6-61 . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance When Trailer Towing 4-64 . . . . . . . . . . . . . . . . .
Malfunction Indicator Lamp 2-77 . . . . . . . . . . . . . . . . . . . . . .
Manual Front Seat 1-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manual Mirror 2-59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manual Selectable Ride 2-41 . . . . . . . . . . . . . . . . . . . . . . . . . .
Manual Transmission
Check 7
-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid 6-22, 7-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shifting 2-24, 2-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting Your Engine 2-16 . . . . . . . . . . . . . . . . . . . . . . . . . .
Manual Windows 2-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Memory Seat 1-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Message Center 2-82 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Messages
Battery 2
-82 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cargo Lamp On 2-87 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Change Engine Oil 2-86 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Check Coolant Temp 2-84 . . . . . . . . . . . . . . . . . . . . . . . . . .
Check Eng Oil Level 2-85 . . . . . . . . . . . . . . . . . . . . . . . . . .
Check Eng Oil Pressure 2-85 . . . . . . . . . . . . . . . . . . . . . . . .
Engine Overheated 2-85 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Coolant 2-84 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Fuel 2-87 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Low Washer Fluid 2
-87 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reduced Engine Power 2-85 . . . . . . . . . . . . . . . . . . . . . . . .
Security 2-86 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service 4WD 2-86 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Trans Fluid Hot 2-82 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Methanol 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mirrors 2-56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Camper Type 2-59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convex Outside 2-60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrochromic Day/Night Rearview 2-56 . . . . . . . . . . . . . .
Heated Outside Rearview 2-59, 3-6 . . . . . . . . . . . . . . . . . . .
Inside Day/Night Rearview 2-56 . . . . . . . . . . . . . . . . . . . . .
Manual 2-59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Remote Control 2-59 . . . . . . . . . . . . . . . . . . . . . . . . .
MMT 6-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Model Reference vi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mountain Roads 4
-38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
New Vehicle Break-In 2-13 . . . . . . . . . . . . . . . . . . . . . . . . . .
Night Vision 4-31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Normal Maintenance, Normal Replacement Parts 6-77 . . . . . .
Odometer 2-69 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Odometer, Trip 2-69 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Off-Road Driving 4-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Off-Road Recovery 4-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil, Engine 6-12, 7-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Filter 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Life Monitor 6-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OnStar
System 2-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Opener, Garage Door 2-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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9-8
Overheated Engine Protection 5-9 . . . . . . . . . . . . . . . . . . . . . .
Overheating Engine 5-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Owner Checks and Services 7-18 . . . . . . . . . . . . . . . . . . . . . . .
Owner Publications, Ordering 8-11, 8-12 . . . . . . . . . . . . . . . .
Paint Spotting, Chemical 6-61 . . . . . . . . . . . . . . . . . . . . . . . .
Park, Shifting Into 2-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Park, Shifting Out of 2-37 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parking
At Night 2
-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake 2-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake Mechanism Check 7-22 . . . . . . . . . . . . . . . . . . . . . . .
Lots 2-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Over Things That Burn 2-38 . . . . . . . . . . . . . . . . . . . . . . . .
With a Trailer 4-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Your Vehicle, Manual Transmission 2-38 . . . . . . . . . . . . . .
Passenger Compartment Air Filter 3-5, 6-18, 6-77 . . . . . . . . .
Passenger Position 1-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Passing 4-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Passlock
2-12, 2-86 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Periodic Maintenance Inspections 7-23 . . . . . . . . . . . . . . . . . .
Pickup Conversion to Chassis Cab 4-53 . . . . . . . . . . . . . . . . .
Power
Accessory Outlet 2
-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Door Locks 2-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option Fuses 6-64 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Remote Control Mirror 2-59 . . . . . . . . . . . . . . . . . . . . . . . .
Seats 1-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Steering 4-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Steering Fluid 6-32, 7-25 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Winches 4-70 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Windows 2-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pregnancy, Use of Safety Belts 1
-24 . . . . . . . . . . . . . . . . . . . .
Problems on the Road 5-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Protecting Exterior Bright Metal Parts 6-59 . . . . . . . . . . . . . . .
Publications, Service and Owner 8-11, 8-12 . . . . . . . . . . . . . .
Radio Reception 3-26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Radios 3-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rain, Driving In 4-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reading Lamps 2-54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear
Axle 6
-25, 7-26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Outside Seat Position 1-38 . . . . . . . . . . . . . . . . . . . . . . . . . .
Safety Belt Comfort Guides 1-41 . . . . . . . . . . . . . . . . . . . . .
Seat Passengers 1-37 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Towing 5-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Window Defogger 3-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Access Door 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Seat 1-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rearview Mirror 2-56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrochromic Day/Night 2-56 . . . . . . . . . . . . . . . . . . . . . .
Inside Day/Night 2-56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reclining Seatbacks 1-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recommended Fluids and Lubricants 7-25 . . . . . . . . . . . . . . .
Recovery Hooks 5-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recreational Vehicle Towing 4-44 . . . . . . . . . . . . . . . . . . . . . .
Reduced Engine Power Message 2-85 . . . . . . . . . . . . . . . . . . .
Refrigerants, Air Conditioning 6-76 . . . . . . . . . . . . . . . . . . . .
Replacement
Bulbs 6
-38, 6-73 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wheel 6-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacing Safety Belts 1-66 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reporting Safety Defects 8-10 . . . . . . . . . . . . . . . . . . . . . . . . .