1999 CHEVROLET TAHOE engine overheat

yellowblue
5-10 If No Steam Is Coming From Your Engine
If you get an engine overheat warning but see or hear no
steam, the problem may not be too serious. Sometimes
the engine can get a little too hot when you:

Climb a long hill on a hot day.

Stop after high
-speed driving.

Idle for long periods in traffic.

Tow a trailer. See ªDriving on Gradesº in the Index.
If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. If you have an air conditioner and it's on, turn it off.
2. Turn on your heater to full hot at the highest fan
speed and open the window as necessary.
3. If you're in a traffic jam, shift to NEUTRAL (N);
otherwise, shift to the highest gear while
driving
-- AUTOMATIC OVERDRIVE (
).If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning doesn't come back on, you can
drive normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there's still no sign of steam, push down the
accelerator until the engine speed is about twice as fast
as normal idle speed for at least three minutes while
you're parked. If you still have the warning, turn off the
engine and get everyone out of the vehicle until it
cools down.
You may decide not to lift the hood but to get service
help right away.

yellowblue
5-13
NOTICE: (Continued)
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.
If there seems to be no leak, start the engine again.
See if the engine cooling fan speed increases when idle
speed is doubled by pushing the accelerator pedal down.
If it doesn't, your vehicle needs service. Turn off
the engine.
How to Add Coolant to the Coolant
Recovery Tank (Gasoline Engine)
If you haven't found a problem yet, but the coolant level
isn't at or above the COLD mark, add a 50/50 mixture
of clean, drinkable water and DEX
-COOL
engine
coolant at the coolant recovery tank. (See ªEngine
Coolantº in the Index for more information.)
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:
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.

yellowblue
5-14
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 the coolant in the coolant recovery tank is at or
above the COLD mark, start your vehicle.
If the overheat warning continues, there's one more
thing you can try. You can add the proper coolant
mixture directly to the radiator, but be sure the cooling
system is cool before you do it.

yellowblue
5-36
For four-door utility models equipped with an
underbody spare tire carrier, follow these instructions to
restore a spare or flat tire:
1. Lay the tire on the ground at the rear of the vehicle.
Position the tire so that the valve stem is pointed
down and to the rear of the vehicle.
2. Tilt the retainer downward and through the wheel
opening. Make sure that the retainer is fully seated
across the underside of the wheel.
3. Attach the ratchet, with the UP mark facing you,
near the hook at the end of the jack handle. Insert the
other end, on an angle, through the hole in the rear
bumper and into the hoist shaft.
4. Raise the tire fully against the underside of the
vehicle. Continue turning the ratchet until there are
two ªclicksº or ªratchets.º The spare tire hoist
cannot be over
-tightened.
5. Grasp and push against the tire to be sure it is stored
securely and does not move.
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.

yellowblue
6-25
NOTICE:
Your radiator 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. Be sure the arrows on the cap
line up with the overflow tube on the radiator
filler neck.
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 AC
 thermostat
is recommended.
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 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
NOTICE: (Continued)

yellowblue
6-26
NOTICE: (Continued)
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.
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.

yellowblue
6-27
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.
Checking Coolant
The coolant recovery tank is located on the passenger's
side at the rear corner of the engine compartment.
The vehicle must be on a level surface. When your engine
is cold, the coolant level should be at the COLD mark, or
a little higher. When your engine is warm, the level should
be at the HOT mark, or a little higher.
Adding Coolant
If you need more coolant, add the proper DEX
-COOL

coolant mixture at the coolant recovery tank.

yellowblue
9-4
Easy Entry Seat (2-Door Utility) 1-7 . . . . . . . . . . . . . . . . . . .
Electric Tailgate Glass Release 2-33 . . . . . . . . . . . . . . . . . . . .
Electrical Equipment, Adding 2-14, 3-27, 6-60 . . . . . . . . . . .
Electrical System 6-60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrochromic Day/Night Rearview
Mirror with Compass 2
-43 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrochromic Day/Night Rearview
Mirror with Compass/Temperature Display 2
-47 . . . . . . . . .
Electrochromic Outside Rearview Mirrors 2-52, 3-9 . . . . . . .
Electronic Compass 2-43, 2-47 . . . . . . . . . . . . . . . . . . . . . . . .
Engine 6-10, 6-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant 6-25, 7-44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Heater 2-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Level Check 7-38 . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Temperature Gage 2-76 . . . . . . . . . . . . . . . . . . . . .
Cooling System 6-68 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust 2-29, 4-41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Identification 6-59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Level Check 7-38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overheating 5-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Running While Parked 2-30 . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications 6-67 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting Your 2-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Oil 6-12, 6-69, 7-44 . . . . . . . . . . . . . . . . . . . . . . . . . .
Adding 6-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additives 6-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking 6-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure Gage 2-79 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Used 6-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
When to Change 6-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Entry to the Rear Seat (Suburban Second Seat) 1
-11 . . . . . . . .
Ethanol 6-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust, Engine 2-29, 4-41 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exterior Lamps 2-40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fabric Cleaning 6-51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filling a Portable Fuel Container 6-8 . . . . . . . . . . . . . . . . . . . .
Filling Your Tank 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter, Air 6-16, 6-68 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter, Engine Oil 6-15, 6-68 . . . . . . . . . . . . . . . . . . . . . . . . . .
Finish Care 6-55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Finish Damage 6-57 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
First Gear, Automatic Transmission 2-18 . . . . . . . . . . . . . . . .
Flashers, Hazard Warning 5-2 . . . . . . . . . . . . . . . . . . . . . . . . .
Flat Tire, Changing 5-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid Capacities 6-68 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid Leak Check 6-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluids and Lubricants 7-44 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Folding the Rear Seat (2-Door Utility) 1-8 . . . . . . . . . . . . . . .
Folding the Rear Seat (4-Door Models) 1-10 . . . . . . . . . . . . .
Foreign Countries, Fuel 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Four-Wheel Drive 2-19, 6-22 . . . . . . . . . . . . . . . . . . . . . . . . .
French Language Manual ii. . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Axle 6
-24, 7-45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Axle Locking Feature 2-19 . . . . . . . . . . . . . . . . . . . . . . .
Front Park/Turn Signal Bulb Replacement 6-38, 6-39 . . . . . .
Front Sidemarker Lamp Bulb Replacement 6-40 . . . . . . . . . . .
Front Towing 5-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .