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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 parked on a level surface.
When your engine is cold, the coolant level should
be at the FULL COLD mark or higher.
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Cooling System (Gas and
DURAMAX
®/Isuzu Engines)
When you decide it is safe to lift the hood, here is
what you will see:
A. Engine Fan
B. Coolant Surge TankIf 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, do not do anything else until it cools down.
The vehicle should be parked on a level surface.
The coolant level should
be at the FULL COLD
mark or higher. If it is
not, 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.
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{CAUTION:
Heater and radiator hoses, and other
engine parts, can be very hot. Do not
touch them. If you do, you can be burned.
Do not run the engine if there is a leak. If
you run the engine, it could lose all
coolant. That could cause an engine re,
and you could be burned. Get any leak
xed before you drive the vehicle.
If there seems to be no leak, start the engine
again. The engine cooling fan speed should
increase when idle speed is doubled by pushing
the accelerator pedal down. If it does not,
your vehicle needs service. Turn off the engine.
Notice:Engine damage from running your
engine without coolant is not covered by your
warranty.Notice:Using coolant other than DEX-COOL
®
may cause premature engine, heater core,
or radiator corrosion. In addition, the engine
coolant could require changing sooner, at
30,000 miles (50 000 km) or 24 months,
whichever occurs rst. Any repairs would not
be covered by your warranty. Always use
DEX-COOL
®(silicate-free) coolant in your
vehicle.
How to Add Coolant to the Coolant
Surge Tank
If you have not found a problem yet, check to see
if coolant is visible in the surge tank. If coolant
is visible but the coolant level is not at the FULL
COLD mark or higher, add a 50/50 mixture of
clean, drinkable water and DEX-COOL
®coolant at
the coolant surge tank, but be sure the cooling
system, including the coolant surge tank pressure
cap, is cool before you do it. SeeEngine
Coolant (Gas and DURAMAX
®/Isuzu Engines) on
page 284orEngine Coolant (Caterpillar®Diesel
Engines) on page 287for more information.
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If no coolant is visible in the surge tank, add
coolant as follows:
{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 coolant surge tank pressure
cap — even a little — they can come out at
high speed. Never turn the cap when the
cooling system, including the coolant
surge tank pressure cap, is hot. Wait for
the cooling system and coolant surge
tank pressure cap to cool if you ever have
to turn the pressure cap.
{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 would
not get the overheat warning. Your engine
could catch re 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.
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{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. Do not spill
coolant on a hot engine.
1. 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
about one full turn. 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 slowly,
and remove it.
3. Fill the coolant surge tank with the proper
mixture, to the FULL COLD mark.
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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 COLD mark.
5. Then replace the pressure cap. Be sure the
pressure cap is hand-tight and fully seated.
Engine Fan Noise
Your vehicle has a clutched engine cooling fan.
When the clutch is engaged, the fan spins faster to
provide more air to cool the engine. In most
everyday driving conditions, the clutch is not fully
engaged. This improves fuel economy and
reduces fan noise. Under heavy vehicle loading,
trailer towing and/or high outside temperatures, the
fan speed increases when the clutch engages.
So you may hear an increase in fan noise. This is
normal and should not be mistaken as the
transmission slipping or making extra shifts. It is
merely the cooling system functioning properly.
The fan will slow down when additional cooling is
not required and the clutch disengages.
You may also hear this fan noise when you start
the engine. It will go away as the fan clutch
disengages.
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(28)= 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.
(29)= Drain, flush, and refill cooling system.
This service can be complex; you should
have your dealer perform this service. See
Part C: Recommended Fluids and Lubricants
on page 397for 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.
(30)= Change the lubricant. See
Part C: Recommended Fluids and
Lubricants on page 397.
(31)= Front axle service: Re-pack upper
kingpin roller bearing.(32)= Air brake service:
•Inspect brake lines and hoses for proper
hook-up, binding, leaks, cracks, chafing,
etc. Inspect drum brake linings for wear or
cracks. Inspect other brake parts at each
wheel, including drums and wheel speed
sensor wiring. Check brake pedal for
excessive free play or travel (or every
6 months, whichever occurs first) and have
serviced if needed. Check brakes more often
if driving habits and conditions result in
frequent braking. Replace air dryer cartridge
only if excessive oil or moisture is present.
A small amount of oil in the system is normal
and should not be considered as a reason
to replace the cartridge.
•Test air lines for leaks; tighten as needed.
Replace compressor filter.
•Inspect air parking brake chamber for leaks
and damage. Inspect lines and hoses for
leaks, cracks, chafing, etc. Also check
all attachments for tightness, wear, or damage.
Note: The spring brake section of the rear
brake diaphragms are non-serviceable.
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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
Engine Exhaust on page 131andRunning
the Engine While Parked on page 132.
Windshield Wipers and Washers Check
Check operation and condition of the wiper
blades. Check the flow of the washer spray.
Defroster Check
Move the control to the defrost symbol and the fan
to HI or the high symbol. Then check the airflow
from the ducts at the inside base of the windshield.
Mirrors and Sun Visors Check
Check that friction joints hold mirrors and sun
visors in place.
Seat Adjuster Check
When adjusting a manual seat, be sure seat
adjusters latch by attempting to move the seat
after latching.
394