1999 GMC C-SERIES engine overheat

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6-23
Engine Coolant (Gasoline Engine)
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 252F (122C).

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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6-24 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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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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6-48 Muffler/Catalytic Converter Assemblies
(Diesel Engines)
Some vehicles equipped with a Caterpillar
diesel engine
utilize a catalytic converter
-muffler assembly. If your
vehicle is equipped with a catalytic converter
-muffler,
some special procedures may need to be followed when
servicing your vehicle. Consult your GM Truck dealer
who is an authorized Caterpillar

engine dealer
for service.
To determine your vehicle's muffler type, examine the
muffler outer housing. If your system is a catalytic
converter
-muffler type, the housing will be stamped
with the CAT logo.
Tires
Your new vehicle comes with high-quality tires made by
a leading tire manufacturer. If you ever have questions
about your tire warranty and where to obtain service, see
your GM Warranty booklet for details.
CAUTION:
Poorly maintained and improperly used tires
are dangerous.

Overloading your tires can cause
overheating as a result of too much friction.
You could have an air
-out and a serious
accident. See ªLoading Your Vehicleº in
the Index.

Underinflated tires pose the same danger as
overloaded tires. The resulting accident
could cause serious injury. Check all tires
frequently to maintain the recommended
pressure. Tire pressure should be checked
when your tires are cold.

Overinflated tires are more likely to be cut,
punctured or broken by a sudden
impact
-- such as when you hit a pothole.
Keep tires at the recommended pressure.

Worn, old tires can cause accidents. If your
tread is badly worn, or if your tires have
been damaged, replace them.
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6-68
Electrical System
Add-On Electrical Equipment
NOTICE:
Don't add anything electrical to your vehicle
unless you check with your dealer first. Some
electrical equipment can damage your vehicle
and the damage wouldn't be covered by your
warranty. Some add
-on electrical equipment can
keep other components from working as
they should.
Headlamp Wiring
The headlamp wiring is protected by a circuit breaker in
the light switch. An electrical overload will cause the
lights to go on and off, or in some cases to remain off.
If this happens, have your headlamp wiring checked
right away.
Windshield Wiper Fuses
The windshield wiper motor is protected by a circuit
breaker inside the motor and a circuit breaker in the fuse
block. If the motor overheats, the wipers will stop until
the motor cools. If the overload is caused by an
electrical problem, be sure to get it fixed.
Fusible Links
A fusible link is a short piece of wire several gage sizes
smaller than the circuit it protects. It will melt in an
overload situation, opening the circuit.
Your starter relay and other circuits have these fusible
links. The size is printed on the insulation. If the insulation
is burned beyond recognition, consult your GM dealer for
the proper size. Replace a fusible link with one of the
same size and insulation type. Fusible link insulation is a
special purpose high
-temperature material.
The hydraulic brake booster motor feed circuit and
starter relay circuit are protected by a fusible link.
Vehicles with a diesel engine have a fusible link for the
intake heater feed circuit. Vehicles equipped with an
electronically controlled diesel engine also have a
fusible link for the engine control unit.
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9-4
Engine (Continued)
Fuse Blocks 6-69, 6-72 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Identification 6-67 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil 6-13, 6-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Filters and PCV Valves 6-77 . . . . . . . . . . . . . . . . . . . . .
Oil Level Check 7-23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overheating 5-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Road Speed Governor 2-54 . . . . . . . . . . . . . . . . . . . . . . . . .
Running While Parked 2-30 . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications 6-74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starter Over-Crank Protection 2-7 . . . . . . . . . . . . . . . . . . . .
Starting 2-7, 2-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Oil 6-13, 6-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additives 6-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking 6-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diesel Engines 6-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filters 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Life Monitor 6-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure Gage 2-66 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Used 6-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
What Kind to Use 6-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
When to Add 6-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
When to Change 6-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ether Injection System 6-46 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust
Brake 2
-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine 2-29, 2-30, 4-27 . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Check 7-26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fabric Cleaning 6-59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filling a Portable Fuel Container 6-8 . . . . . . . . . . . . . . . . . . . .
Filling Your Tank 6-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter
Air Cleaner 6
-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Compressor 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Oil 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filterminder Gage 2-70 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Finish Care 6-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Finish Damage 6-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flashers, Hazard Warning 5-2 . . . . . . . . . . . . . . . . . . . . . . . . .
Flat Tire, Changing 5-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid Leaks Check 7-27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluids and Lubricants 7-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Footnotes 7-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
French Language Manual ii. . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Towing 5
-10, 5-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Wheel Bearings with Oil-Filled Hubs 6-47 . . . . . . . . . .
Fuel
Diesel Engine 6
-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filling a Portable Container 6-8 . . . . . . . . . . . . . . . . . . . . . .
Filling Your Tank 6-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter 6-44, 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gage 2-68 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gasoline Engine 6-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tank Capacity 6-76 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Water in Fuel 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuels in Foreign Countries -- Gasoline 6-6 . . . . . . . . . . . . . . .
Fuses and Circuit Breakers 6-69 . . . . . . . . . . . . . . . . . . . . . . .
Fusible Links 6-68 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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