2008 GMC YUKON coolant temperature

When towing at high altitude on steep uphill grades,
consider the following: Engine coolant at higher altitudes
will boil at a lower temperature than at or near sea
level. 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 5-31.
Parking on Hills
{CAUTION:
You really should not park your vehicle, with a
trailer attached, on a hill. If something goes
wrong, your rig could start to move. People
can be injured, and both your vehicle and the
trailer can be damaged.But if you ever have to park your rig on a hill, here’s
how to do it:
1. Apply your regular brake, but don’t shift into
PARK (P) yet.
2. Have someone place chocks under the trailer
wheels.
3. When the wheel chocks are in place, release the
regular brakes until the chocks absorb the load.
4. Reapply the regular brakes. Then apply your
parking brake and shift into PARK (P).
5. If you have a four-wheel-drive vehicle, be sure the
transfer case is in a drive gear and not in
NEUTRAL.
6. Release the regular brakes.
4-60

Consistency of Readings
Always check the uid level at least twice using the
procedures described. Consistency (repeatable
readings) is important to maintaining proper uid level. If
uid is added, it may take 15 minutes or longer to
obtain an accurate reading because of residual uid
draining down the dipstick tube. If inconsistent readings
persist, check the transmission breather to be sure it
is clean and not clogged. If readings are still
inconsistent, contact your dealer/retailer.
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 5-31.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.
5-28

Adding Coolant
If more coolant is needed, add the proper DEX-COOL®
coolant mixture at the surge tank, but only when the
engine is cool.
{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.
When replacing the pressure cap, make sure it is
hand-tight and fully seated.
Coolant Surge Tank Pressure Cap
If your vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual for more information.
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 5-14for more
information on location.
Engine Overheating
There is a coolant temperature gage on your vehicle’s
instrument panel. SeeEngine Coolant Temperature
Gage on page 3-47.
In addition, ENGINE OVERHEATED STOP ENGINE,
ENGINE OVERHEATED IDLE ENGINE, and a ENGINE
POWER IS REDUCED message comes on in the
Driver Information Center (DIC) on the instrument panel.
SeeDIC Warnings and Messages on page 3-64.
5-31

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 the vehicle has an air conditioner and it is on,
turn it off.
2. Turn on the heater to the highest temperature and
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.
If there is still no sign of steam and your vehicle has 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 parked.
If there is still no sign of steam and your vehicle has an
electric cooling fan, idle the engine for ve minutes
while 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 might 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
ENGINE POWER IS REDUCED 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.
5-33

(c)Visually inspect hoses and have them replaced if they
are cracked, swollen, or deteriorated. Inspect all pipes,
fittings, and clamps; replace with genuine parts as
needed. To help ensure proper operation, a pressure test
of the cooling system and pressure cap and cleaning the
outside of the radiator and air conditioning condenser is
recommended at least once a year.
(d)Inspect wiper blades for wear, cracking, or
contamination. Clean the windshield and wiper blades, if
contaminated. Replace wiper blades that are worn or
damaged. See Windshield Wiper Blade Replacement on
page 5-62andWindshield, Backglass, and Wiper
Blades on page 5-113 for more information.
(e)Make sure the safety belt reminder light and safety
belt assemblies are working properly. Look for any
other loose or damaged safety belt system parts. If you
see anything that might keep a safety belt system
from doing its job, have it repaired. Have any torn or
frayed safety belts replaced. Also see Checking
the Restraint Systems on page 1-92.
(f)Lubricate all key lock cylinders, hood latch assembly,
secondary latch, pivots, spring anchor, release pawl,
rear compartment hinges, outer liftgate handle pivot
points, rear door detent link, roller mechanism, liftgate
handle pivot points, latch bolt, fuel door hinge, cargo
door hinge, locks, and folding seat hardware. More
frequent lubrication may be required when exposed to
a corrosive environment.Applying silicone grease on weatherstrips with a clean
cloth will make them last longer, seal better, and
not stick or squeak.
(g)Check vent hose at transfer case for kinks and
proper installation.
(h)Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as found in taxi, police, or delivery
service.
(i)Drain, flush, and refill cooling system. This service
can be complex; you should have your dealer/retailer
perform this service. See Engine Coolant on page 5-28
for what to use. Inspect hoses. Clean radiator,
condenser, pressure cap, and filler neck. Pressure test
the cooling system and pressure cap.
(j)A fluid loss in any vehicle system could indicate a
problem. Have the system inspected and repaired and
the fluid level checked. Add fluid if needed.
(k)Inspect system. Check all fuel and vapor lines and
hoses for proper hook-up, routing, and condition. Check
that the purge valve works properly, if equipped.
Replace as needed.
6-8

Chemical Paint Spotting.................................5-114
Child Restraints
Child Restraint Systems...............................1-57
Infants and Young Children...........................1-54
Lower Anchors and Tethers for Children..........1-61
Older Children.............................................1-51
Securing a Child Restraint in a Rear Seat
Position..................................................1-69
Securing a Child Restraint in the Center
Front Seat Position...................................1-71
Securing a Child Restraint in the Right
Front Seat Position...................................1-72
Where to Put the Restraint...........................1-60
Cigarette Lighter.............................................3-23
Cleaning
Aluminum or Chrome-Plated Wheels.............5-113
Exterior Lamps/Lenses................................5-112
Fabric/Carpet............................................5-109
Finish Care...............................................5-112
Instrument Panel, Vinyl, and Other Plastic
Surfaces...............................................5-110
Interior.....................................................5-108
Leather....................................................5-110
Tires........................................................5-114
Underbody Maintenance.............................5-114
Washing Your Vehicle.................................5-111
Weatherstrips............................................5-111
Windshield, Backglass, and Wiper Blades......5-113Climate Control System...................................3-23
Dual Automatic............................................3-26
Outlet Adjustment........................................3-33
Rear Air Conditioning and Heating System......3-33
Rear Air Conditioning and Heating System,
Electronic................................................3-35
Clock, Setting.................................................3-82
Collision Damage Repair..................................7-11
Compass...............................................2-49, 2-52
Content Theft-Deterrent....................................2-22
Control of a Vehicle
.......................................... 4-3
Coolant
Engine Temperature Gage............................3-47
Heater, Engine............................................2-30
Surge Tank Pressure Cap.............................5-31
Cooling System..............................................5-34
Cruise Control................................................3-13
Cruise Control Light........................................3-53
Cupholder(s)..................................................2-71
Customer Assistance Information
Courtesy Transportation.................................. 7-9
Customer Assistance for Text
Telephone (TTY) Users............................... 7-5
Customer Assistance Offices........................... 7-5
Customer Satisfaction Procedure..................... 7-2
GM Mobility Reimbursement Program............... 7-6
Reporting Safety Defects to General Motors....7-14
3

Engine
Air Cleaner/Filter.........................................5-19
Check and Service Engine Soon Light............3-48
Coolant......................................................5-28
Coolant Heater............................................2-30
Coolant Temperature Gage...........................3-47
Drive Belt Routing.......................................6-16
Engine Compartment Overview......................5-14
Exhaust.....................................................2-47
Fan Noise..................................................5-39
Oil .............................................................5-15
Oil Life System...........................................5-18
Overheated Protection Operating Mode...........5-33
Overheating................................................5-31
Running While Parked..................................2-48
Starting......................................................2-28
Entry Lighting.................................................3-20
Event Data Recorders.....................................7-16
Exit Lighting...................................................3-20
Extender, Safety Belt.......................................1-50
Exterior Lamps...............................................3-16
F
Filter
Engine Air Cleaner......................................5-19
Finish Damage.............................................5-114
Flashers, Hazard Warning.................................. 3-6
Flash-to-Pass................................................... 3-9Flat Tire........................................................5-87
Flat Tire, Changing.........................................5-88
Flat Tire, Storing...........................................5-103
Fluid.....................................................5-22, 5-24
Power Steering...........................................5-39
Windshield Washer......................................5-40
Fog Lamp
Fog ...........................................................3-19
Fog Lamp Light..............................................3-53
Four-Wheel Drive....................................2-38, 5-54
Front Axle......................................................5-55
Fuel............................................................... 5-5
Additives...................................................... 5-6
California Fuel.............................................. 5-6
E85 (85% Ethanol)........................................ 5-7
Filling a Portable Fuel Container....................5-11
Filling the Tank............................................. 5-9
Fuels in Foreign Countries.............................. 5-8
Gage.........................................................3-54
Gasoline Octane........................................... 5-5
Gasoline Specications.................................. 5-6
Low Warning Light.......................................3-55
Fuses
Center Instrument Panel Fuse Block.............5-119
Fuses and Circuit Breakers.........................5-117
Instrument Panel Fuse Block.......................5-118
Underhood Fuse Block...............................5-120
Windshield Wiper.......................................5-117
5

G
Gage
Engine Coolant Temperature.........................3-47
Fuel..........................................................3-54
Oil Pressure...............................................3-51
Speedometer..............................................3-39
Tachometer.................................................3-39
Voltmeter Gage...........................................3-44
Garage Door Opener.......................................2-64
Gasoline
Octane........................................................ 5-5
Specications............................................... 5-6
Glove Box.....................................................2-71
GM Mobility Reimbursement Program.................. 7-6
H
Hazard Warning Flashers................................... 3-6
Head Restraints..............................................1-10
Headlamp
Aiming.......................................................5-56
Headlamps
Bulb Replacement.......................................5-59
Daytime Running Lamps...............................3-17
Exterior Lamps............................................3-16
Flash-to-Pass............................................... 3-9
Halogen Bulbs............................................5-59
High/Low Beam Changer................................ 3-9
On Reminder..............................................3-17Heated Seats................................................... 1-5
Heater...........................................................3-23
Heater...........................................................3-26
Highbeam On Light.........................................3-53
Highway Hypnosis...........................................4-28
Hill and Mountain Roads..................................4-29
Hood
Checking Things Under................................5-12
Release.....................................................5-13
Horn............................................................... 3-6
How to Wear Safety Belts Properly...................1-35
I
Ignition Positions.............................................2-26
Infants and Young Children, Restraints...............1-54
Ination - Tire Pressure...................................5-72
Instrument Panel
Overview..................................................... 3-4
Instrument Panel (I/P)
Brightness..................................................3-20
Cluster.......................................................3-38
J
Jump Starting.................................................5-46
6