1980/02/25 Caterpillar

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


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.


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}
1980/02/11 Warning: Avoid Use Of Fuel Mixtures Of High Volatility. If You Are Exposed To Such Mixtures, Be Aware Of The Hazards Involved And Take Proper Precautions{1280}
1980/02/04 Real Value Available Through Caterpillar Remanufacturing Programs{0374}
1980/02/04 Change To Gear On Accessory Drive Shaft Assembly Gives Longer Service Life{1207,1206}
1980/02/04 New Cylinder Liner Has Improved Design To Keep Liner Temperatures Lower{1216}
1980/01/28 Oil Drain Hole Added To Spacer Plate Cylinder Block To Permit Use Of Scroll Fuel System{1201,1221}
1980/01/28 New Attachment Air Compressor Group and Lines Groups Have Improved Design{1065}
1980/01/28 Installation Procedures For 5N5880 Remote Shut-Off Group And 5N6336 Oil Pressure Indicator Gauge Group{7418,7403,7455}
1980/01/28 New 6V199 Socket For Use On Fasteners In Areas With Limited Clearance{0612}
1980/01/21 New Fuel Injection Nozzle Assembly Used{1254}
1980/01/21 Extended Shafts Now Available For Front Power Takeoff Units{3055}
1980/01/21 Cooling System Improvements Prevent Expansion Tank Leakage{1354,1380,1153}
1980/02/25 Revision Of Special Instruction Form No. SMHS7267, "Use Of 5P8709 Tool Group For Alignment Of Piston Cooling Jets" Has Important Changes{1307}
1980/02/25 Stronger Braces Used Between Air Cleaner And Engine{1051}
1980/02/25 Plunger Movement Must Be Adjusted When New Rack Shut-Off Solenoid Is Installed{1259}
1980/02/25 Drawings Available For Six Tools Used During Repairs Of Damaged Pin Bores In Two-Piece Booms{6501,0665}
1980/02/25 Identification Of Fuel Injection Lines And Nozzle Bodies For Different Combustion Systems{1252,1254}
1980/03/03 Spacer Plate Block Group Used For Parts Service Of Block Group With Counterbore Design{1101,1201}
1980/03/03 Connecting Rod Changes And Replacement Information{1218}
1980/03/03 Fuel Heaters Are Now Available For Field Installation{1296}
1980/03/24 Inspect Regulator Cover Assembly When Overcooling Is A Problem{1350,1380}
1980/03/24 Crankshaft Rear Seal And Wear Sleeve Are Now Serviced As A Group Instead Of Separate Parts{1161}
1980/03/24 New Top Piston Ring Has Plasma-Coated Face{1215}
1980/03/24 8S2252 Carbon Seal Tool Can Be Adapted For Use On 8N7001 Fuel Nozzle Assembly{0611,1254}
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