FUEL SHUTOFF TEST

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START-UP OVERRIDE VALVE CHECK

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TM-5-2815-232-14 Engine Diesel Caterpillar Model 3508 Manual

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UG-8L GOVERNOR

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

NOTICE

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

NOTICE

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.

adjustment bolt.

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

needed.

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