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

  TM-9-2320-272-24-1 - Page 161 of 1015

TM 9-2320-272-24-1
Table 2-2. Mechanical Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Step 1.
Inspect exhaust piper, stack, and muffler for secure connections, cracks, breaks, and
excessive rust.
a. If loose, tighten.
b.
If leaking at pipe connection, replace gasket(s) (para. 3-48).
c.
If cracked, broken, or rusted, replace (para, 3-48). If loose, tighten.
Step 2.
Check exhaust manifold for leaks. If leaking, notify DS maintenance.
NOTE
Perform step 8 for M989A2 series vehicles,
Step 3.
Inspect turbocharger for secure mounting and exhaust leaks.
If turbocharger mounting is loose or leaks exhaust, notify DS maintenance.
21. EXHAUST FUMES IN CAB
Inspect exhaust pipes, stack, and muffler for secure connections, cracks, breaks, and excessive rust.
a. If loose, tighten.
a.
If leaking at pipe connection, replace gasket(s) (para. 3-48).
b.
If cracked, broken, or rusted, replace (para. 3-48).
END OF TESTING!
COOLING SYSTEM
22. ENGINE DOES NOT REACH NORMAL OPERATING TEMPERATURE
WARNING
Extreme care should be taken when removing surge tank filler cap
if temperature gauge reads above 175°F (79°C). Steam or hot
coolant under pressure may cause injury.
NOTE
If STE/ICE is available, perform NG31 - Gauge Test (para. 2-24).
Step 1.
Start engine (TM 9-2320-272-10). Remove surge tank cap and visually check coolant for
proper circulation.
Stop engine. If coolant is seen circulating and temperature is below 175°F (79°C), replace
thermostat (para. 3-65 or 3-66).
Step 2.
Test coolant temperature gauge, sending unit, and electrical leads for malfunction
(Electrical Troubleshooting, para. 2-22).
a.
Replace coolant temperature gauge if defective (para. 3-86).
b.
Replace coolant temperature sending unit if defective (para. 3-93).
NOTE
Perform step 3 for M939A2 series vehicles.
Step 3.
Observe fan clutch and actuator for proper operation.
Replace fan clutch and/or actuator if defective (para. 3-74).
END OF TESTING!
2-73


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