2020 GMC SIERRA DENALI engine

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
Vehicle Care 343
Automatic Transmission
Fluid
When to Check and Change
Automatic Transmission Fluid
It is usually not necessary to check
the transmission fluid level. The only
reason for fluid loss is a
transmission leak or overheated
transmission. This vehicle is not
equipped with a transmission fluid
level dipstick. There is a special
procedure for checking and
changing the transmission fluid in
these vehicles. Because this
procedure is difficult, this should be
done at the dealer. Contact the
dealer for additional information or
the procedure can be found in the
service manual. SeePublication
Ordering Information 0471.
Caution
Use of the incorrect automatic
transmission fluid may damage
the vehicle, and the damage may
(Continued)
Caution (Continued)
not be covered by the vehicle
warranty. Always use the correct
automatic transmission fluid. See
Recommended Fluids and
Lubricants0452.
Change the fluid and filter at the
scheduled maintenance intervals
listed in Maintenance Schedule
0 441. Be sure to use the
transmission fluid listed in
Recommended Fluids and
Lubricants 0452.
Engine Air Filter Life
System
If equipped, this feature provides
the engine air filter ’s remaining life
and best timing for a change. The
timing to change an engine air filter
depends on driving and
environmental conditions.
When to Change the Engine
Air Filter
When the Driver Information Center
(DIC) displays a message to replace
the engine air filter at the next oil
change, follow this timing.
When the DIC displays a message
to replace the engine air filter soon,
replace the engine air filter at the
earliest convenience.
The system must be reset after the
engine air filter is changed.
If the DIC displays a message to
check the engine air filter system,
see your dealer.
How to Reset the Engine Air
Filter Life System
To reset:
1. Place the vehicle in P (Park).
2. Display the Air Filter Life on the DIC. See Driver Information
Center (DIC) (Base Level)
0 147 or
Driver Information Center (DIC)
(Midlevel and Uplevel) 0148.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
344 Vehicle Care
3. PressTon the steering wheel,
or press the trip odometer reset
stem if the vehicle does not
have DIC controls, to move to
the Reset/Disable display area.
Select Reset then press the
thumbwheel or press the reset
stem for several seconds.
4. Press the thumbwheel or the reset stem to confirm the reset.
Engine Air Cleaner/Filter
The engine air cleaner/filter is on
the driver side of the engine
compartment. See Engine
Compartment Overview 0332.
When to Inspect the Engine Air
Cleaner/Filter
If the vehicle is not equipped with
the engine air filter life system see
Maintenance Schedule 0441 for
intervals on inspecting and
replacing the engine air cleaner
filter.
How to Inspect/Replace the
Engine Air Cleaner/Filter
Do not start the engine or have the
engine running with the engine air
cleaner/filter housing open. Before
removing the engine air cleaner/
filter, make sure that the engine air
cleaner/filter housing and nearby
components are free of dirt and
debris. Do not clean the engine air
cleaner/filter or components with
water or compressed air. To inspect or replace the engine air
cleaner/filter:
5.3L V8 Engine (L84) Shown, 2.7L
L4 Engine (L3B), 4.3L V6 Engine(LV3), 5.3L V8 Engine (L82), and 6.2L V8 Engine (L87) Similar
1. Air Duct Clamp
2. Electrical Harness Connector
3. Screws
1. Locate the air cleaner/filter assembly. See Engine
Compartment Overview 0332.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
Vehicle Care 345
2. Disconnect the outlet duct byloosening the air duct
clamp (1).
3. Disconnect the electrical harness connector (2) from the
cover.
4. Remove the three screws on top of the cover of the housing,
then slide and lift the cover.
5. Lift and remove the engine air cleaner/filter.
6. Lightly tap and shake the engine air cleaner/filter, away
from the vehicle, to release
loose dust and dirt. Replace
the engine air filter if damaged.
7. Reverse steps 2–5 to reinstall the engine air cleaner/filter
cover housing.
8. If equipped, reset the engine air filter life system after
replacing the engine air filter.
See Engine Air Filter Life
System 0343.
6.6L V8 Engine (L8T)
1. Locate the air cleaner/filter assembly. See Engine
Compartment Overview 0332.
2. Remove the eight screws on top of the cover of the housing,
then lift the cover.
3. Remove the engine air cleaner/ filter from the housing. Take
care to dislodge as little dirt as
possible.
4. Clean the engine air cleaner/ filter sealing surfaces and the
housing. 5. Inspect or replace the engine
air cleaner/filter.
6. Reverse Steps 2–4 to reinstall the filter cover housing.
7. If equipped, reset the engine air filter life system after
replacing the engine air filter.
see Engine Air Filter Life
System 0343.
{Warning
Operating the engine with the air
cleaner/filter off can cause you or
others to be burned. Use caution
when working on the engine. Do
not start the engine or drive the
vehicle with the air cleaner/filter
off, as flames may be present if
the engine backfires.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
346 Vehicle Care
Caution
If the air cleaner/filter is off, dirt
can easily get into the engine,
which could damage it. Always
have the air cleaner/filter in place
when driving.
Cooling System
If the vehicle has the Duramax
diesel engine, see the Duramax
diesel supplement.
The cooling system allows the
engine to maintain the correct
working temperature.
2.7L L4 Engine (L3B)
4.3L V6 Engine (LV3)
5.3L V8 Engine (L84) Shown, 5.3LV8 Engine (L82) and 6.2LV8 Engine (L87) Similar
1. Engine Electric Cooling Fans (Out of View)
2. Coolant Surge Tank and Pressure Cap
{Warning
An underhood electric fan can
start up even when the engine is
not running and can cause injury.
Keep hands, clothing, and tools
away from any underhood
electric fan.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
Vehicle Care 347
6.6L V8 Engine (L8T)
1. Engine Cooling Fan (Outof View)
2. Coolant Surge Tank and Pressure Cap
{Warning
Do not touch heater, radiator, a/c
pipes or hoses, or other engine
parts. They can be very hot and
can burn you. Do not run the
engine if there is a leak; all
coolant could leak out. That could
(Continued)
Warning (Continued)
cause an engine fire and can
burn you. Fix any leak before
driving the vehicle.
Engine Coolant
The cooling system in the vehicle is
filled with DEX-COOL engine
coolant. This coolant is designed to
remain in the vehicle for 5 years or
240 000 km (150,000 mi), whichever
occurs first.
The following explains the cooling
system and how to check and add
coolant when it is low. If there is a
problem with engine overheating,
seeEngine Overheating 0351.
What to Use
{Warning
Plain water, or other liquids such
as alcohol, can boil before the
proper coolant mixture will. With
(Continued)
Warning (Continued)
plain water or the wrong mixture,
the engine could get too hot but
there would not be an overheat
warning. The engine could catch
fire and you or others could be
burned.
Use a 50/50 mixture of clean,
drinkable water and DEX-COOL
coolant. This mixture:
. Gives freezing protection down
to−37 °C (−34 °F), outside
temperature.
. Gives boiling protection up to
129 °C (265 °F), engine
temperature.
. Protects against rust and
corrosion.
. Will not damage aluminum parts.
. Helps keep the proper engine
temperature.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
348 Vehicle Care
Caution
Do not use anything other than a
mix of DEX-COOL coolant that
meets GM Standard
GMW3420 and clean, drinkable
water. Anything else can cause
damage to the engine cooling
system and the vehicle, which
would not be covered by the
vehicle warranty.
Never dispose of engine coolant by
putting it in the trash, or by pouring
it on the ground, or into sewers,
streams, or bodies of water. Have
the coolant changed by an
authorized service center, familiar
with legal requirements regarding
used coolant disposal. This will help
protect the environment and your
health.
Checking Coolant
The coolant surge tank is in the
engine compartment on the driver
side of the vehicle. See Engine
Compartment Overview 0332. The vehicle must be on a level
surface when checking the coolant
level.
All Engines Except 6.6L V8 (L8T)
Engine
6.6L V8 (L8T) Engine Only
Check to see if coolant is visible in
the coolant surge tank. If the coolant
inside the coolant surge tank is
boiling, wait until it cools down. The
coolant level should be at or above
the indicated mark. If it is not, there
may be a leak in the cooling
system.
If coolant is visible but the coolant
level is not at or above the indicated
mark, see the following sections on
how to add coolant to the coolant
surge tank following.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
Vehicle Care 349
Automatic Coolant Service Fill
Instructions (L3B Engine)
See 3.0L Duramax Diesel
supplement for the diesel engine
procedure.
If equipped, this feature assists in
filling and removing air from the
cooling system after service of
components or when coolant is
added after being too low.
To activate the fill and air removal
process:1. With a cold system, add coolant to the indicated mark
on the surge tank.
2. Replace the cap on the surge tank.
3. Connect the vehicle to a battery charger.
4. Set the ignition to Service or Accessory Mode. See Ignition
Positions (Keyless Access)
0 208 or
Ignition Positions (Key Access)
0 210.
5. Turn off the air conditioning. 6. Set the parking brake.
7. At the same time, press the
accelerator and the brake for
automatic transmission
vehicles for two seconds, then
release.
At the end of the cycle, check the
coolant level in the surge tank and
add coolant if it is low. Turn off the
vehicle, allow the Electronic Control
Module (ECM) to go to sleep, about
two minutes, and repeat Steps 3–7.
Listen for pump activation and
movement of the control valves
while watching the level of the
coolant in the surge tank. If the tank
empties, turn the ignition off,
carefully remove the surge tank cap,
refill to the indicated mark, and
repeat Steps 3–6. The fill and air
removal process will run for
approximately 10 minutes.
How to Add Coolant to the
Coolant Surge Tank for
Gasoline Engines Except L3B
If the vehicle has a diesel engine,
see “Cooling System” in the
Duramax diesel supplement for the
proper coolant fill procedure.
{Warning
Spilling coolant on hot engine
parts can burn you. Coolant
contains ethylene glycol and it will
burn if the engine parts are hot
enough.
{Warning
Plain water, or other liquids such
as alcohol, can boil before the
proper coolant mixture will. With
plain water or the wrong mixture,
the engine could get too hot but
there would not be an overheat
(Continued)

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 8/27/19
350 Vehicle Care
Warning (Continued)
warning. The engine could catch
fire and you or others could be
burned.
{Warning
Steam and scalding liquids from a
hot cooling system are under
pressure. Turning the pressure
cap, even a little, can cause them
to come out at high speed and
you could be burned. Never turn
the cap when the cooling system,
including the pressure cap, is hot.
Wait for the cooling system and
pressure cap to cool.
Caution
Failure to follow the specific
coolant fill procedure could cause
the engine to overheat and could(Continued)
Caution (Continued)
cause system damage. If coolant
is not visible in the surge tank,
contact your dealer.
If no coolant is visible in the surge
tank, add coolant.
1. 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 a hiss is heard, wait for
that to stop. A hiss means
there is still some pressure left.
2. Keep turning the pressure cap slowly, and remove it. 3. Fill the coolant surge tank with
the proper mixture to the full
cold mark.
4. With the coolant surge tank pressure cap off, start the
engine and let it run until the
engine coolant temperature
gauge indicates approximately
90 °C (195 °F).
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
indicated mark.
5. Replace the pressure cap tightly.
6. Verify coolant level after the engine is shut off and the
coolant is cold. If necessary,
repeat coolant fill procedure
Steps 1–6.