HYDRAMECHANICAL PROTECTIVE SYSTEM
TESTING AND ADJUSTING
FUEL SHUTOFF TEST
Remove the hose assembly, connector and
shutoff valve from the engine. Connect the oil supply to
Hold open the air inlet shutoff valve with a length
the thermostatic pilot valve.
of wire. (If another person is present, the valve can be
held open by hand.) Pull the red, emergency. knob.
All of the above tests are performed at low idle.
Since the air inlet shutoff valve has been held open, the
Successful shutdowns and alarms at low idle indicate
fuel shutoff actuator should stop the engine. The low oil
correct operation. Therefore, it is not necessary to
pressure, high coolant temperature alarms should also
perform the tests at high idle.
be activated, if so equipped.
SHUTOFF SPEED SETTING ADJUSTMENT
NOTE: When major disassembly or adjustment of the
Before starting the engine, make sure the air inlet
shutoff control group is needed, see CATERPILLAR
shutoff is reset so the protective system can
FUEL INJECTION TEST BENCH BOOK, FORM NO.
operate, if needed, and to prevent damage to the
SEHS7466 for the complete specifications and test
engine at start up.
bench procedures to use.
LOW OIL PRESSURE TEST
Disconnect the oil supply line that is installed
A mechanic with training in governor adjustments is
between the thermostatic pilot valve and the shutoff
the ONLY one that should perform the following
control group, at the control group. Attach a 3N4847
procedure. Severe engine damage could occur if
Hose Assembly to the control. Use a 7D5363 Connector
this procedure is not followed. Also, check the
to adapt a 3R3837 Shutoff Valve to the end of the hose.
capabilities of driven equipment to make sure
damage will not occur if run at overspeed.
NOTE: If the engine is not equipped with a thermostatic
pilot valve, remove the plug from where line (4) would
connect to the shutoff control group.
Check and make sure the engine fuel settings
are correct. See FUEL SETTING CHECK in the
Close the valve and start the engine and operate
Engine TESTING AND ADJUSTING section of
it at low idle. The engine will run normally.
this Service Manual.
Place the end of the hose in a bucket or other
Start the engine and operate it at low idle.
container and open the valve to drain approximately one-
half liter (one U.S. pint) of oil to lower the oil pressure.
This will actuate the low oil pressure protection
circuit and cause engine shutdown through the fuel
shutoff actuator or activate the low oil pressure, high
coolant temperature alarms, if so equipped. The air inlet
shutoff should not be activated by this test.
NOTE: The fuel shutoff actuator will not be activated in a
protective system that gives overspeed protection only,
when a low oil pressure fault is simulated.
SHUTOFF CONTROL GROUP
If the fuel shutoff actuator is not activated by this
test, check the actuator, oil lines or electrical
1. Emergency manual shutoff. 2. Overspeed setting
connections, and the shutoff control group for defects.
If the alarms fail to activate, make sure the
Before any adjustment to the shutoff control
pressure switch on the control valve group, the wiring
overspeed setting is made, check for correct
and alarms work correctly to locate and repair parts as
operation of the hydramechanical protective