2001 GMC SIERRA Owner's Manual

6-27
5. Perform a hot check at the first opportunity after the
normal operating temperature of 160
F (71
C) to
200
F (93
C) is reached.
6. If the fluid level is in the acceptable range, push the
dipstick back in all the way.
Hot Check Procedure
The fluid must be hot to ensure an accurate check.
The fluid level rises as temperature increases.
1. Operate the transmission in DRIVE (D) range until
the normal operating temperature of 160
F (71
C)
to 200
F (93
C) is reached.
2. Pull out the dipstick and wipe it with a clean rag or
paper towel.
3. Push it back in all the way, wait three seconds and
then pull it back out again. Repeat the check
procedure to verify the reading.4. Safe operating level is within the HOT RUN band
on the dipstick. The width of the HOT RUN band
represents approximately 1.06 quart (1.0 liter) of
fluid at normal operating temperature.
5. If the fluid level is not within the HOT RUN band,
add or drain fluid as necessary to bring the fluid
level to within the HOT RUN band.
6. If the fluid level is in the acceptable range, push the
dipstick back in all the way.
Consistency of Readings
Always check the fluid level at least twice using the
procedures described previously. Consistency (repeatable
readings) is important to maintaining proper fluid level.
If inconsistent readings persist, check the transmission
breather to be sure it is clean and unclogged. If readings
are still inconsistent, contact your dealer.

6-28 How to Add Fluid
Refer to the Maintenance Schedule to determine what
kind of transmission fluid to use. See ªRecommended
Fluids and Lubricantsº in the Index.
Add fluid only after checking the transmission fluid while
it is hot. (A cold check is used only as a reference.)
If the fluid level is low, add only enough of the proper
fluid to bring the level up to the HOT area for a hot
check. It doesn't take much fluid, generally less than
one pint (0.5 L). Don't overfill.
NOTICE:
We recommend you use only fluid labeled
DEXRON-III, because fluid with that label is
made especially for your automatic transmission.
Damage caused by fluid other than DEXRON
-III
is not covered by your new vehicle warranty.

After adding fluid, recheck the fluid level as
described under ªHow to Check.º

When the correct fluid level is obtained,
push the dipstick back in all the way.
Manual Transmission Fluid
When to Check
A good time to have it checked is when the engine oil
is changed. See your maintenance schedule to find out
when to change your transmission fluid.
How to Check
Because this operation can be a little difficult, you
may choose to have this done at your GM dealership
service department.
If you do it yourself, be sure to follow all the
instructions here, or you could get a false reading.
NOTICE:
Too much or too little fluid can damage your
transmission. Too much can mean that some of
the fluid could come out and fall on hot engine
parts or exhaust system parts, starting a fire.
Be sure to get an accurate reading if you check
your transmission fluid.

6-29
Check the fluid level only when your engine is off, the
vehicle is parked on a level place and the transmission is
cool enough for you to rest your fingers on the
transmission case.
Then, follow these steps:
5-Speed for VORTEC 4300 V6 and 4800 V8 engines
shown, other manual transmissions similar1. Remove the filler plug.
2. Check that the lubricant level is up to the bottom
of the filler plug hole.
3. If the fluid level is good, install the plug and be sure
it is fully seated. If the fluid level is low, add more
fluid as described in the next steps.
How to Add Fluid
Here's how to add fluid. Refer to the Maintenance
Schedule to determine what kind of fluid to use. See
ªRecommended Fluids and Lubricantsº in the Index.
1. Remove the filler plug.
2. Add fluid at the filler plug hole. Add only enough
fluid to bring the fluid level up to the bottom of the
filler plug hole.
3. Install the filler plug. Be sure the plug is fully seated.

6-30
Hydraulic Clutch
The hydraulic clutch linkage in your vehicle is
self
-adjusting. The clutch master cylinder reservoir is
filled with hydraulic clutch fluid.
It is not necessary to regularly check clutch fluid unless
you suspect there is a leak in the system. Adding fluid
won't correct a leak.
A fluid loss in this system could indicate a problem.
Have the system inspected and repaired.
When to Check and What to Use
Refer to the Maintenance
Schedule to determine how
often you should check the
fluid level in your clutch
master cylinder reservoir
and for the proper fluid.
See ªOwner Checks
and Servicesº and
ªRecommended Fluids and
Lubricantsº in the Index.
How to Check and Add Fluid
The proper fluid should be added if the level does not
reach the bottom of the diaphragm when it's in place in
the reservoir. See the instructions on the reservoir cap.
Rear Axle
When to Check Lubricant
Refer to the Maintenance Schedule to determine
how often to check the lubricant. Additional rear axle
scheduled maintenance is required when trailer towing.
See ªScheduled Maintenance Servicesº in the Index for
more information.

6-31 How to Check Lubricant
1500 Series shown, 2500 LD Series similar.
2500 HD and 3500 Series located on rear axle cover.
The proper level for the 1500 Series is from 5/8 inch to
1 5/8 inch (15 mm to 40 mm) below the filler plug.
The proper level for the 2500/3500 Series is from
0 to 3/8 inch (0 to 10 mm) below the filler plug.
Add only enough fluid to reach the proper level.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See ªRecommended Fluids and
Lubricantsº in the Index.
Four-Wheel Drive
Most lubricant checks in this section also apply to
four
-wheel-drive vehicles. However, they have two
additional systems that need lubrication.
Transfer Case
When to Check Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant. See ªPeriodic Maintenance
Inspectionsº in the Index.
How to Check Lubricant
Manual Transfer Case

6-32
Automatic Transfer Case
If the level is below the bottom of the filler plug hole,
you'll need to add some lubricant. Add enough lubricant
to raise the level to the bottom of the filler plug hole.
Use care not to overtighten plug.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See ªRecommended Fluids
and Lubricantsº in the Index.
Front Axle
When to Check Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant. See ªScheduled
Maintenance Servicesº in the Index.
How to Check Lubricant
If the level is below the bottom of the filler plug hole,
you may need to add some lubricant.

6-33
When the differential is cold, add enough lubricant
to raise the level to 1/2 inch (12 mm) below the filler
plug hole.
When the differential is at operating temperature
(warm), add enough lubricant to raise the level to the
bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See ªRecommended Fluids
and Lubricantsº in the Index.
Engine Coolant
The cooling system in your vehicle is filled with
DEX
-COOL engine coolant. This coolant is designed
to remain in your vehicle for 5 years or 150,000 miles
(240 000 km), whichever occurs first, 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, see ªEngine Overheatingº in
the Index.A 50/50 mixture of clean, drinkable water and
DEX
-COOL coolant will:

Give freezing protection down to
-34F (-37C).

Give boiling protection up to 265F (129C).

Protect against rust and corrosion.

Help keep the proper engine temperature.

Let the warning lights and gages work as
they should.
NOTICE:
When adding coolant, it is important that you
use only DEX
-COOL (silicate-free) coolant.
If coolant other than DEX-COOL is added to
the system, premature engine, heater core or
radiator corrosion may result. In addition, the
engine coolant will require change sooner
-- at
30,000 miles (50 000 km) or 24 months,
whichever occurs first. Damage caused by the
use of coolant other than DEX
-COOL is not
covered by your new vehicle warranty.

6-34 What to Use
Use a mixture of one-half clean, drinkable water and
one
-half DEX-COOL
coolant which won't damage
aluminum parts. If you use this coolant mixture,
you don't need to add anything else.
CAUTION:
Adding only plain water to your cooling system
can be dangerous. Plain water, or some other
liquid like 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 wouldn't
get the overheat warning. Your engine could
catch fire 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 wouldn't 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 the proper coolant, you don't have to
add extra inhibitors or additives which claim to
improve the system. These can be harmful.