TM 5-3895-346-14
ENGINE OVERHAUL
TROUBLESHOOTING (ENGINE)
Chart 3
ABNORMAL ENGINE OPERATION
SUGGESTED REMEDY
1. Check the engine coolant temperature gauge and, if the temperature does not reach 160to 185 (71to
F
85 ) while the engine is operating, consult the Abnormal Engine Coolant Temperature chart.
C
2. Check engine fuel spill back and if the return is less than specified, consult the No Fuel or Insufficient Fuel
chart.
3. Check the injector timing and the position of the injector racks. If the engine was not tuned correctly,
perform an engine tune-up. Erratic engine operation may also be caused by leaking injector spray tips.
Replace the faulty injectors.
4. Check the compression pressures within the cylinders and consult the Hard Starting chart if compression
pressures are low.
5. Erratic engine operation may be caused by governor-to-injector operating linkage bind or by faulty engine
tune-up. Perform the appropriate engine tune-up procedure as outlined for the particular governor used.
6. If the engine is equipped with a throttle delay, check for the proper setting, binding or burrs on the piston or
bracket, and a plugged discharge orifice.
If equipped with a fuel modulator, determine if there is any interference with the roller assembly or roller con-
tact with the cam at wide-open-throttle (WOT) position. Check for burrs and binding on the piston and bracket
bore. Determine correctness of the installed fuel modulator spring and check if the spring has taken a
permanent set, or if the spring rate is too high.
Perform an engine tune-up if performance is not satisfactory.
Check the engine gear train timing. An improperly timed gear train will result in a loss of power due to the
valves and injectors being actuated at the wrong time in the engine's operating cycle.
7. Perform a Fuel Flow Test and, if less than the specified fuel is returning to the fuel tank, consult the No Fuel
or Insufficient Fuel chart.
8. Check for damaged or dirty air cleaners and clean, repair or replace damaged parts.
Remove the air box covers and inspect the cylinder liner ports. Clean the ports if they are over 50% plugged.
Check for blower air intake obstruction or high exhaust-back pressure. Clean, repair or replace faulty parts.
Check the compression pressures (consult the Hard Starting chart).
9. Incorrect operation of the engine may result in excessive loads on the engine.
Operate the engine
according to the approved procedures.
10. Refer to Item 13 on Chart 4.
11. Check the ambient air temperature. A power decrease of 0.15 to 0.50 horsepower per cylinder, depending
upon injector size, for each 10 (6 ) temperature rise above 90 (32 ) will occur. Relocate the engine air
F
C
F
C
intake to provide a cooler source of air.
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