Copyright © 1996 General Motors Corp. 3–3
PREVENTIVE MAINTENANCE
PREVENTIVE MAINTENANCE
mission parts, or clog passages. Check the fluid level
by the following procedures and record any abnormal
level on your maintenance records.
b. Cold Check
NOTE:
•
A Cold Check is performed with dipsticks sim-
ilar to those illustrated in Figure 3–2 and 3–3.
•
The fluid level rises as sump temperature in-
creases. DO NOT FILL above the REF FILL
(COLD RUN) band if the transmission fluid is
below normal operating temperature.
(1) Park the vehicle on a level surface, apply
the parking brake, and block the wheels.
(2) Run the engine at 1000–1500 rpm for
one minute to purge air from the system. Allow the
engine to idle. Shift to
D
(Drive) and then to
R
(Re-
verse) to fill the hydraulic circuits with fluid. Then,
shift to
N
(Neutral) or
P
(Park). The sump tempera-
ture should be 60–120°F (16–50°C).
(3) After wiping the dipstick clean, check
the fluid level. If the fluid level is within the REF FILL
(COLD RUN) band (Figures 3–2, 3–3), the level is
satisfactory for operating the transmission until the
fluid is hot enough to perform a Hot Check. If the fluid
level is not within these parameters, raise or lower the
fluid level to bring it within the band.
(4) Perform a Hot Check at the first opportu-
nity after normal operating temperature is reached
(160–200°F (71–93°C) sump temperature; 180–220°F
(82–104°C) converter-out temperature).
c. Hot Check
NOTE:
A Hot Check is performed with all dipstick designs
(Figures 3–1 through 3–3).
(1) Operate the transmission until normal op-
erating temperature is reached (160–200°F (71–93°C)
sump temperature; 180–220°F (82–104°C) converter-
out temperature). Shift to
D
(Drive) and then to
R
(Re-
verse) to fill the hydraulic circuits with fluid.
(2) Park the vehicle on a level surface and
shift to
N
(Neutral) or
P
(Park). Apply the parking
brake, block the wheels, and allow the engine to idle.
(3) After wiping the dipstick clean, check
the fluid level. The safe operating level is anywhere
between the FULL and ADD lines (Figure 3–1),
within the HOT RUN band (Figure 3–2), or below the
HOT OVERFULL mark and above the COLD RUN
band (Figure 3–3).
(4) If the fluid level is outside of these pa-
rameters, raise or lower the fluid level to bring it
within the correct markings on the dipstick.
3–6. KEEPING TRANSMISSION
FLUID CLEAN
Transmission fluid must be handled in clean containers
to prevent foreign material from entering the transmis-
sion. Lay the dipstick in a clean place while filling the
transmission.
3–7. TRANSMISSION FLUID
RECOMMENDATIONS
a. Recommended Automatic Transmission
Fluid and Viscosity Grade
(1) Hydraulic fluids (oils) used in the transmis-
sion are important influences on transmission perfor-
mance, reliability, and durability. Use DEXRON
®
-III flu-
ids for standard duty, highway applications. Use C-4
fluids for severe duty and off-highway applications.
(2) Some DEXRON
®
-III fluids are also
qualified as C-4 fluids. To ensure the fluid is qualified
for use in Allison Transmissions, check for a
DEXRON
®
-III or C-4 fluid license, or approval num-
bers on the container, or consult the lubricant manu-
facturer. Consult your Allison Transmission dealer or
distributor before using other fluid types; fluid types
such as Type F, and universal farm fluids may or may
not be properly qualified for use in your Allison trans-
mission.
CAUTION:
Containers or fillers that have been used to han-
dle antifreeze or engine coolant solution must
never be used for transmission fluid. Antifreeze
and coolant solutions contain ethylene glycol
which, if introduced into the transmission, can
cause the clutch plates to fail.
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