1980/02/25 Caterpillar


How To Check Operation Of Hydramechanical Shutoffs On D379B, D398B, D399 Engines{7418}

Usage:




This article tells how to check the operation of the shutoffs on D379B, D398B, and D399 Engines. You can easily check the operation of the emergency manual shutoff, and the low oil pressure and overspeed shutoffs.

Write a note in the Service Manual for these engines about this article. Write the note in the Testing & Adjusting Section of Form SEBR0511, Page 3-1. This section does not yet have this procedure:

1. There is an oil supply hose between the water temperature sensor and the shutoff control. Disconnect this hose at the shutoff control, and install a hand operated valve at this location.

2. Install a hose from the hand operated valve to the oil pan sump. Close the valve; this stops oil flow and the system will operate in a normal manner when the engine is started.

3. Start the engine and operate it at low idle.

4. At low idle, pull emergency manual shutoff (red knob). Both air inlet shutoffs must close, and the rack must move to the shutoff position.

NOTE: Open both air inlet shutoffs before starting engine again.

5. Start engine again and operate it at low idle.

6. Open the valve to lower the oil pressure. This will cause the oil pressure shutoff to stop the engine if the shutoff works correctly. The rack cylinder must move and stop the engine, but the air shutoffs must not close.

7. Close the shutoff valve.

8. Start engine and operate it at high idle.

9. Again, open the shutoff valve to decrease the oil pressure at high idle. The rack cylinder must stop the engine, but the air inlet shutoffs must not close.

10. Remove hand operated valve and the oil line added to the sump. Connect the oil supply hose from the temperature sensor to the shutoff control.

11. Start engine and operate it at high idle.

12. Turn the high idle adjustment screw slowly to increase engine rpm. The air inlet shutoffs must close and the rack cylinder move the rack to "shutoff" at about 18% above the full load rpm. This is about 1416 rpm for an engine rated at 1200 rpm.

OR

13. If the engine does not stop at about 18% above full load rpm, slowly increase engine rpm 100 more. (This is about 1516 rpm for a 1200 rpm engine.) If the shutoff still does not stop the engine, decrease the engine rpm and turn the overspeed adjusting bolt (see Item 1 on Page 4-8 of Service Manual) one turn counterclockwise. Again, increase the engine rpm to see if it will be shut off. If not, do the procedure again until the engine stops at the desired overspeed rpm.

14. Make a final check of the rpm for overspeed shutoff. To do this, make a rapid or sudden increase to the engine rpm and read the maximum rpm. When the maximum rpm is correct, tighten the locknut on the adjusting bolt.

NOTE: Open both air inlet shutoffs before starting engine again.

Caterpillar Information System:

1980/02/11 Use The Correct Water Temperature Contactor{1350,1100}
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1980/02/25 Identification Of Fuel Injection Lines And Nozzle Bodies For Different Combustion Systems{1252,1254}
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1980/03/03 Connecting Rod Changes And Replacement Information{1218}
1980/03/03 Fuel Heaters Are Now Available For Field Installation{1296}
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