engine overheat GMC YUKON 2007 User Guide

Turn Signals When Towing a Trailer
The arrows on your instrument panel will
ash whenever you signal a turn or lane change.
Properly hooked up, the trailer lamps will also
ash, telling other drivers you’re about to
turn, change lanes or stop.
When towing a trailer, the arrows on your
instrument panel will ash for turns even if the
bulbs on the trailer are burned out. Thus, you may
think drivers behind you are seeing your signal
when they are not. It’s important to check
occasionally to be sure the trailer bulbs are still
working.
Driving On Grades
Reduce speed and shift to a lower gearbefore
you start down a long or steep downgrade. If you
don’t shift down, you might have to use your
brakes so much that they would get hot and no
longer work well.You can tow in DRIVE (D). You may want to shift
the transmission to THIRD (3) or, if necessary,
a lower gear selection if the transmission shifts
too often (e.g., under heavy loads and/or hilly
conditions).
You may also want to activate the tow/haul mode
if the transmission shifts too often. See “Tow/Haul
Mode” underTowing a Trailer on page 400.
When towing at high altitude on steep uphill
grades, consider the following: Engine coolant at
or near sea level will boil at a lower temperature
than at higher altitudes. If you turn your engine
off immediately after towing at high altitude
on steep uphill grades, your vehicle may show
signs similar to engine overheating. To avoid this,
let the engine run while parked (preferably on
level ground) with the automatic transmission
in PARK (P) for a few minutes before turning the
engine off. If you do get the overheat warning,
seeEngine Overheating on page 448.
411

Service........................................................ 420
Accessories and Modications................... 421
California Proposition 65 Warning.............. 421
Doing Your Own Service Work.................. 422
Adding Equipment to the Outside
of Your Vehicle...................................... 423
Fuel............................................................. 423
Gasoline Octane........................................ 423
Gasoline Specications.............................. 424
California Fuel........................................... 424
Additives................................................... 424
Fuels in Foreign Countries........................ 425
Filling the Tank......................................... 426
Filling a Portable Fuel Container............... 428
Checking Things Under the Hood.............. 428
Hood Release........................................... 429
Engine Compartment Overview.................. 430
Engine Oil................................................. 432
Engine Oil Life System.............................. 435Engine Air Cleaner/Filter............................ 437
Automatic Transmission Fluid.................... 440
Engine Coolant.......................................... 445
Coolant Surge Tank Pressure Cap............ 448
Engine Overheating................................... 448
Overheated Engine Protection
Operating Mode..................................... 450
Cooling System......................................... 451
Engine Fan Noise..................................... 456
Power Steering Fluid................................. 457
Windshield Washer Fluid........................... 458
Brakes...................................................... 459
Battery...................................................... 463
Jump Starting............................................ 464
All-Wheel Drive........................................... 469
Rear Axle.................................................... 470
Front Axle................................................... 471
Headlamp Aiming........................................ 473
Section 5 Service and Appearance Care
417

How to Check Automatic
Transmission Fluid
Notice:Too much or too little uid can
damage your transmission. Too much can
mean that some of the uid could come out
and fall on hot engine parts or exhaust system
parts, starting a re. Too little uid could
cause the transmission to overheat. Be sure to
get an accurate reading if you check your
transmission uid.
Before checking the uid level, prepare your
vehicle as follows:
1. Start the engine and park your vehicle on a
level surface. Keep the engine running.
2. Apply the parking brake and place the shift
lever in PARK (P).
3. With your foot on the brake pedal, move the
shift lever through each gear range, pausing
for about three seconds in each range.
Then, move the shift lever back to PARK (P).4. Allow the engine to idle (500 – 800 rpm)
for at least one minute. Slowly release the
brake pedal.
5. Keep the engine running and press the
Trip/Fuel button until TRANS TEMP
(Transmission Temperature) displays on the
Driver Information Center (DIC).
6. Using the TRANS TEMP reading, determine
and perform the appropriate check procedure.
If the TRANS TEMP reading is not within
the required temperature ranges, allow
the vehicle to cool, or operate the vehicle until
the appropriate transmission uid temperature
is reached.
441

Engine Coolant
The cooling system in your vehicle is lled with
DEX-COOL®engine coolant. This coolant is
designed to remain in your vehicle for ve years or
150,000 miles (240 000 km), whichever occurs
rst, 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, seeEngine
Overheating on page 448.
A 50/50 mixture of clean, drinkable water and
DEX-COOL
®coolant will:
Give freezing protection down to
−34°F (−37°C).
Give boiling protection up to 265°F (129°C).
Protect against rust and corrosion.
Help keep the proper engine temperature.
Let the warning lights and gages work as
they should.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
the rst maintenance service after each
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.
445

What to Use
Use a mixture of one-half clean, drinkable water
and one-half DEX-COOL®coolant which will
not damage aluminum parts. If you use this coolant
mixture, you do not need to add anything else.
{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:If you use an improper coolant
mixture, your engine could overheat and be
badly damaged. The repair cost would not 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 extra inhibitors and/or
additives in your vehicle’s cooling system, you
could damage your vehicle. Use only the
proper mixture of the engine coolant listed in
this manual for the cooling system. See
Recommended Fluids and Lubricants on
page 561for more information.
446

Coolant Surge Tank Pressure Cap
Notice:If the pressure cap is not tightly
installed, coolant loss and possible engine
damage may occur. Be sure the cap is properly
and tightly secured.
The coolant surge tank pressure cap must be fully
installed on the coolant surge tank. SeeEngine
Compartment Overview on page 430for more
information on location.
Engine Overheating
You will nd a coolant temperature gage on your
vehicle’s instrument panel. SeeEngine Coolant
Temperature Gage on page 236.
In addition, you will nd an ENGINE
OVERHEATED STOP ENGINE, ENGINE
OVERHEATED IDLE ENGINE, and an ENGINE
POWER IS REDUCED message in the Driver
Information Center (DIC) on the instrument panel.
SeeDIC Warnings and Messages on page 252.
If Steam Is Coming From Your Engine
{CAUTION:
Steam from an overheated engine can burn
you badly, even if you just open the hood.
Stay away from the engine if you see or
hear steam coming from it. Just turn it off
and get everyone away from the vehicle
until it cools down. Wait until there is no
sign of steam or coolant before you open
the hood.
If you keep driving when your engine is
overheated, the liquids in it can catch re.
You or others could be badly burned.
Stop your engine if it overheats, and get
out of the vehicle until the engine is cool.
SeeOverheated Engine Protection
Operating Mode on page 450for
information on driving to a safe place
in an emergency.
448

Notice:If your engine catches re because
you keep driving with no coolant, your vehicle
can be badly damaged. The costly repairs
would not be covered by your warranty.
SeeOverheated Engine Protection Operating
Mode on page 450for information on driving
to a safe place in an emergency.
If No Steam Is Coming From Your
Engine
The ENGINE OVERHEATED STOP ENGINE
or the ENGINE OVERHEATED IDLE ENGINE
message, along with a low coolant condition,
can indicate a serious problem.
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. SeeTowing a Trailer
on page 400.If you get the ENGINE OVERHEATED STOP
ENGINE or the ENGINE OVERHEATED IDLE
ENGINE message with no sign of steam, try this
for a minute or so:
1. If you have an air conditioner and it is on,
turn it off.
2. Turn on your heater to full hot at the highest
fan speed and open the windows as
necessary.
3. In heavy traffic, let the engine idle in
NEUTRAL (N) while stopped. If it is safe to
do so, pull off the road, shift to PARK (P)
or NEUTRAL (N) and let the engine idle.
If you no longer have the overheat warning,
you can drive. Just to be safe, drive slower for
about 10 minutes. If the warning does not
come back on, you can drive normally.
If the warning continues, pull over, stop, and
park your vehicle immediately.
449

If there is still no sign of steam and your vehicle
is equipped with an engine-driven cooling fan,
push down the accelerator until the engine speed
is about twice as fast as normal idle speed for
at least ve minutes while you are parked.
If there is still no sign of steam and your vehicle is
equipped with an electric cooling fan, idle the
engine for ve minutes while you are parked.
If you still have the warning, turn off the engine
and get everyone out of the vehicle until it
cools down. Also, see “Overheated Engine
Protection Operating Mode” later in this section.
You may decide not to lift the hood but to get
service help right away.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 432.
450

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 Fan{CAUTION:
An electric engine cooling fan under the
hood can start up even when the engine
is not running and can injure you. 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.
451

Notice:Engine damage from running your
engine without coolant is not covered by your
warranty. SeeOverheated Engine Protection
Operating Mode on page 450for 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
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 on page 445for more information.
453