Fluid Check Procedure - Allison Transmission AT 500 Series Manual

1–4. FLUID CHECK PROCEDURE
WARNING: When checking the fluid level, be sure the transmission
is in N (Neutral) or P (Park), parking brake and/or emergency brakes
are set and properly engaged, and the wheels are chocked.
Unexpected and possible sudden vehicle movement may occur if
these precautions are not taken.
CAUTION: Dirt and foreign matter must not be permitted to enter
the fluid system. It can cause valves to stick, cause undue wear of
transmission parts, or clog passages.
Always check the fluid level a minimum of two times. Consistency is important in
maintaining accuracy. If inconsistent readings persist, check the transmission
breather and the vent hole in the dipstick fill tube to ensure they are clean and free of
debris. The vent hole is located on the underside of the fill tube just below the seal of
the dipstick cap.
Check the fluid level by the following procedures and record any abnormal fluid
level, milky appearance, or any trace of coolant in the fluid on your maintenance
records. Refer to Paragraph 1–8.
Cold Check
a.
NOTE: The only purpose of the Cold Check is to determine if the
transmission has enough fluid to be safely operated until a Hot Check
can be made.
• Park the vehicle on a level surface, set the parking brake and/or emergency
brakes, and chock the vehicle wheels.
• Run the engine at 1000–1500 rpm for one minute to purge air from the
system. Return engine to idle, then shift to D (Drive) and then to R (Reverse)
to fill the hydraulic circuits with fluid. Then, shift to N (Neutral) or P (Park)
and allow the engine to idle (500–800 rpm). The sump temperature should be
between 60–120°F (16–49°C).
CAUTION: The fluid level rises as sump temperature increases. DO
NOT fill above the COLD RUN band if the transmission fluid is
below normal operating temperature.
• Clean around the end of the fill tube before removing the dipstick. Wipe the
dipstick clean and check the fluid level. If the fluid on the dipstick is within
the COLD RUN band, the level is satisfactory for operating the transmission
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