TM-9-2320-272-23-3
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; FIELD MAINTENANCE MANUAL; VOLUME 3 OF 5
SEPTEMBER 2012
TM-9-2320-272-23-3 - Page 338 of 1469
ADJUSTMENT - Continued
WARNING
Do not allow anyone to stand in front of vehicle when conducting stall test. Vehicle may move.
Failure to comply may result in injury or death to personnel.
CAUTION
•
Do not maintain the stalled condition longer than 30-second intervals due to rapid heating
of transmission oil. Observe transmission oil temperature gauge. Normal operating range
is 120°F to 220°F (49°C to 104°C).
•
Observe engine coolant temperature gauge. Operating temperature is 175°F to 195°F
(79°C to 90°C).
•
If oil temperature reaches 300°F (148°C), or if thirty seconds is insufficient time to
complete needed tests, transmission oil temperature must be lowered or damage to
transmission may result.
•
Run engine at 1,200 to 1,500 rpm with transmission in neutral for two minutes to cool oil
between tests.
NOTE
•
The stall test is conducted when engine and/or transmission are not performing
satisfactorily. The purpose of the stall test is to determine if transmission or engine is the
malfunctioning unit.
•
The vehicle's transmission will stay in first speed during the stall tests regardless of
transmission 5-4-3-2 and 1 quadrant position. Transmission does not and cannot upshift
because the internal mechanism, output shaft, and governor are not turning. The stall
test checks the engine performance, converter clutch operation or installation, and
holding ability of the converter one-way clutch.
•
Refer to TM 9-2320-272-10 for the following steps.
13.
Apply service brakes and place transmission shift lever in any forward drive position 5-4-3-2-1.
14.
Accelerate engine to full throttle (1,900 to 2,050 rpm).
NOTE
Perform Step (15) only if engine speed exceeds 1,700 rpm.
15.
If engine speed exceeds 1,700 rpm, check transmission oil level.
a.
If oil level is low, fill to proper level.
b.
If oil level is correct, repair transmission as necessary.
TM 9-2320-272-23-3
0374
0374-19
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