TM-9-2320-272-10

TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)

TECHNICAL MANUAL; OPERATOR'S MANUAL

SEPTEMBER 2004

CHANGE 2

TM-9-2320-272-10 - Page 356 of 481

TM 9-2320-272-10

Change 2

3-7

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

Table 3-1. Troubleshooting (Contd).

5. ENGINE OVERHEATS AS INDICATED BY ENGINE COOLANT TEMPERATURE

GAUGE

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

will cause injury.

Step 1. Check radiator core for obstructions.

If clogged, remove debris (refer to table 2-1).

Step 2. Check coolant level in surge tank.

If low, add coolant to surge tank until at bottom of fill neck.

Step 3. Check for leakage from radiator, surge tank, hoses, and hose

connections.

If loose, tighten. If still leaking, notify unit maintenance.

Step 4. Check engine oil level.

If low, add oil (para. 2-10).

Step 5. Check radiator fan clutch operation.

If fan blade is not turning, install override lockup bolts (para. 3-14).

6. LOW ENGINE OIL PRESSURE.

Check engine oil level.

If low, add oil (para. 2-10).

NOTE

• If oil pressure is still low, notify unit maintenance.

7. ENGINE FAILURE DURING OPERATION.

Step 1. Check to see if emergency stop cable is pulled out.

On M939A2 series vehicles, manually reset emergency stop. On

M939/A1 series vehicles, notify unit maintenance.

Step 2. Check to see if throttle control solenoid is malfunctioning (M939/A2

series vehicles).

If solenoid is malfunctioning, tie up with strap or rope and finish

mission. Report to unit maintenance as soon as possible.