TM-9-2320-272-24-1
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 1 OF 4
JUNE 1998
TM-9-2320-272-24-1 - Page 556 of 1015
TM 9-2320-272-24-1
THIS TASK COVERS:
a. Removal (Internal Bypass)
b. Cleaning and Inspection (Both Types)
c. Installation (Internal Bypass)
d. Removal (External Bypass)
e. Installation (External Bypass)
APPLICABLE MODELS
M939A2
TOOLS
General mechanic’s too kit (Appendix E, Item 1)
Torque wrench (Appendix E, Item 146)
MATERIALS/PARTS
Gasket (Appendix D, Item 148)
Gasket (Appendix D, Item 149)
Gasket (Appendix D, Item 150)
Gasket (Appendix D, Item 151)
Gasket (Appendix D, Item 152)
Seal (Appendix D, Item 598)
Antiseize tape (Appendix C, Item 72)
REFERENCES (TM)
TM 9-2320-272-10
TM 9-2320-272-24P
EQUIPMENT CONDITION
Parking brake set (TM 9-2320-272-10).
Hood raised and secured (TM 9-2320-272-10).
Drivebelt tensioner removed (para. 3-71)
GENERAL SAFETY INSTRUCTIONS
Do not drain coolant when engine is hot.
NOTE
There are two different bypass systems used for M939A2 engines.
An identifiable difference is the thermostat housing for external
bypass and internal bypass engines.
Do not drain coolant when engine is hot. Severe bums to
personnel may result.
1.
Drain three quarts of coolant from oil cooler drainvalve (11) into container.
2.
Loosen clamp (3) and remove hose (2) from adapter (4).
3.
Loosen alternator link screw (12).
4.
While supporting alternator (15), remove two screws (13) and washers (14) from bracket (16). Pivot
alternator (15) down and move bracket (16) aside.
5.
Remove four screws (17) and bracket (18) from thermostat housing (7).
NOTE
Tag screws for identification in installation.
6.
Remove two screws (1), adapter (4), and gasket (5) from thermostat housing (7). Discard
gasket (5)
7.
Remove two screws (6), thermostat housing (7), and gasket (8) from engine block (10). Discard
gasket (8).
Cover coolant passages. Dirt in cooling system will cause
overheating and engine failure.
8.
Remove two thermostats (9) from engine block (10).
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