engine GMC YUKON 2005 Owner's Manual

Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and the
REDUCED ENGINE POWER message is displayed, an
overheat protection mode which alternates ring
groups of cylinders helps prevent engine damage. In
this mode, you will notice a loss in power and engine
performance. This operating mode allows your vehicle to
be driven to a safe place in an emergency. Driving
extended miles (km) and/or towing a trailer in the
overheat protection mode should be avoided.
Notice:After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any
repair. The engine oil will be severely degraded.
Repair the cause of coolant loss, change the oil and
reset the oil life system. SeeEngine Oil on
page 5-15.
Cooling System
When you decide it is safe to lift the hood, here is what
you will see:
A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine Cooling Fan8100 V8 Engines
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A. Coolant Surge Tank
B. Coolant Surge Tank Pressure Cap
C. Engine Cooling Fan
{CAUTION:
An electric fan under the hood can start up
and injure you even when the engine is not
running. Keep hands, clothing and tools away
from any underhood electric fan.
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. Check the coolant
level after the system cools down. Some amount of
coolant may be lost due to overheating.
The coolant level should
be at or above the FULL
COLD mark. 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. All Other Engines
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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 your vehicle is equipped with an electric engine
cooling fan, check the coolant temperature gage. If the
coolant temperature is approximately 232°F (111°C),
the electric cooling fan should be running. If it is
not, your vehicle needs service. Turn off the engine.
If your vehicle is equipped with an engine-driven cooling
fan, start the engine again and see if the fan speed
increases 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. See
Overheated Engine Protection Operating Mode on
page 5-29for information on driving to a safe place
in an emergency.
Notice:Using coolant other than DEX-COOL®may
cause premature engine, heater core or radiator
corrosion. In addition, the engine coolant may
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 or above the FULL COLD
mark, add a 50/50 mixture ofclean, 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 on page 5-24for 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 (left)
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 the FULL COLD mark.
5. Then replace the pressure cap. Be sure the
pressure cap is hand-tight and fully seated.
Engine Fan Noise
If your vehicle is equipped with 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 fan is spinning slower and 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 as the clutch more fully 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 partially
disengages.
If your vehicle is equipped with electric cooling fans, you
may hear the fans spinning at low speed during most
everyday driving. The fans may turn off if no cooling is
required. Under heavy vehicle loading, trailer towing,
and/or high outside temperatures, or if you are operating
your air conditioning system, the fans change to high
speed and you may hear an increase in fan noise. This
is normal and indicates that the cooling system is
functioning properly. The fans will change to low speed
when additional cooling is no longer required.
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Power Steering Fluid
SeeEngine Compartment Overview on page 5-12for
reservoir location.
When to Check Power Steering Fluid
It is not necessary to regularly check power steering uid
unless you suspect there is a leak in the system or
you hear an unusual noise. A uid loss in this system
could indicate a problem. Have the system inspected
and repaired. 8100 V8 engine
All other engines
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How to Check Power Steering Fluid
Locate the cap with this
symbol. SeeEngine
Compartment Overview on
page 5-12for more
information on location.
To check the power steering uid, do the following:
1. Turn the key off and let the engine compartment
cool down.
2. Wipe the cap and the top of the reservoir clean.
3. Unscrew the cap and wipe the dipstick with
a clean rag.
4. Replace the cap and completely tighten it.
5. Remove the cap again and look at the uid level
on the dipstick.
The level should be at the FULL COLD mark.
If necessary, add only enough uid to bring
the level up to the mark.
What to Use
To determine what kind of uid to use, see
Recommended Fluids and Lubricants on page 6-13.
Always use the proper uid. Failure to use the proper
uid can cause leaks and damage hoses and seals.
Windshield Washer Fluid
What to Use
When you need windshield washer uid, be sure to read
the manufacturer’s instructions before use. If you will
be operating your vehicle in an area where the
temperature may fall below freezing, use a uid that has
sufficient protection against freezing.
Adding Washer Fluid
Your vehicle has a low washer uid message that
comes on when the washer uid is low. The message is
displayed for 15 seconds at the start of each ignition
cycle. When the CHECK WASHER FLUID message is
displayed, you will need to add washer uid to the
windshield washer uid reservoir.
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Open the cap with the
washer symbol on it.
Add washer uid until the
tank is full. SeeEngine
Compartment Overview on
page 5-12for reservoir
location.
Notice:
When using concentrated washer uid, follow
the manufacturer’s instructions for adding
water.
Do not mix water with ready-to-use washer uid.
Water can cause the solution to freeze and
damage your washer uid tank and other parts
of the washer system. Also, water does not
clean as well as washer uid.
Fill your washer uid tank only three-quarters
full when it is very cold. This allows for
expansion if freezing occurs, which could
damage the tank if it is completely full.
Do not use engine coolant (antifreeze) in your
windshield washer. It can damage your washer
system and paint.
Brakes
Brake Fluid
Your brake master cylinder
reservoir is lled with
DOT-3 brake uid. See
Engine Compartment
Overview on page 5-12for
the location of the
reservoir.
There are only two reasons why the brake uid level in
the reservoir might go down. The rst is that the
brake uid goes down to an acceptable level during
normal brake lining wear. When new linings are put in,
the uid level goes back up. The other reason is
that uid is leaking out of the brake system. If it is, you
should have your brake system xed, since a leak
means that sooner or later your brakes will not work
well, or will not work at all.
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So, it is not a good idea to top off your brake uid.
Adding brake uid will not correct a leak. If you add uid
when your linings are worn, then you will have too
much uid when you get new brake linings. You should
add or remove brake uid, as necessary, only when
work is done on the brake hydraulic system.
{CAUTION:
If you have too much brake uid, it can spill on
the engine. The uid will burn if the engine is
hot enough. You or others could be burned,
and your vehicle could be damaged. Add brake
uid only when work is done on the brake
hydraulic system. See “Checking Brake Fluid”
in this section.
Refer to the Maintenance Schedule to determine when
to check your brake uid. SeeScheduled Maintenance
on page 6-4.
Checking Brake Fluid
You can check the brake uid without taking off the cap.
Look at the brake uid
reservoir. The uid level
should be above MIN. If it
is not, have your brake
system checked to
see if there is a leak.
After work is done on the brake hydraulic system,
make sure the level is above the MIN but not over the
MAX mark.
What to Add
When you do need brake uid, use only DOT-3 brake
uid. Use new brake uid from a sealed container
only. SeeRecommended Fluids and Lubricants on
page 6-13.
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