TM-9-2320-272-24-3
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 3 OF 4
JUNE 1998
TM-9-2320-272-24-3 - Page 64 of 799
TM 9-2320-272-24-3
4-54. ENGINE RUN-IN TEST AND IDLE SPEED ADJUSTMENT
THIS TASK COVERS:
a. Engine Run-in Test
b. Idle Speed Adjustment
INITlAIL SETUP:
APPLICABLE MODELS
M939A2
REFERENCES (TM)
LO 9-2320-272-12
TOOLS
TM 9-2320-272-10
General mechanic’s tool kit (Appendix E, Item 1)
TM 9-2320-272-24P
EQUlPMENT CONDITION
PERSONNEL REQUIRED
Parking brake set (TM 9-2320-272-10).
TWO
Hood raised and secured (TM 9-2320-272-10)
a. Engine Run-in Test
1.
Pull emergency engine stop control (4) out all the way.
Do not operate starter continuously for more than 30 seconds at a
time. Wait two minutes between periods of starter operation.
Failure to do so may result in damage to equipment.
2.
Crank engine until oil pressure registers on oil pressure gauge (3).
Prime fuel system if engine fails to start (para. 3-22).
3.
Push emergency engine stop control (4) all the way in.
4.
Start engine (TM 9-2320-272-10) and run at l,000-2,000 rpm for 30 minutes.
5.
Check oil pressure gauge (3) and water temperature gauge (2).
a. If oil pressure gauge (3) does not register or suddenly drops to less than 10 psi (69 kPa), stop
engine and troubleshoot lubrication system (para. 4-2).
b. If water temperature gauge (2) increases above 205°F (96°C), stop engine and allow to cool. If
engine overheats again, troubleshoot cooling system (para. 2-21).
6.
Stop engine and inspect for leaks.
b. Idle Speed Adjustment
Assistant will help with this procedure.
Start engine (TM 9-2320-272-10) and check tachometer (1) for proper idle speed, 550-650 rpm. If idle
speed is not within limits, adjust accelerator linkage (5).
a. Loosen locknut (7).
b. Turn throttle rod (6) clockwise to increase idle speed; counterclockwise to decrease idle speed.
c. Tighten locknut (7).
4-328
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