Introduction

NOTE: For Specifications with illustrations, make reference to Specifications For 3406 Spark Ignited Engine Attachments, Form No. SENR3868. If the Specifications in Form SENR3868 are not the same as in the Systems Operation and Testing And Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

Troubleshooting

Troubleshooting can be difficult. On the following pages there is a list of possible problems. To make a repair to a problem, make reference to the cause and correction.

This list of problems, causes and corrections will only give an indication of where a possible problem can be, and what repairs are needed. Normally, more or other repair work is needed beyond the recommendations in the list. Remember that a problem is not normally caused only by one part, but by the relation of one part with other parts. This list can not give all possible problems and corrections. The serviceman must find the problem and its source, then make the necessary repairs.

NOTE: Problems 1 through 5 are for troubleshooting the self-powered engine protection system. To troubleshoot the energized-to-run (ETR) protection systems, refer to Troubleshooting Guide (ETR), Form No. SENR3609.

Problem Index

1. Contactor Switch (Water Temperature) Fails to Signal Shutoff.

2. Contactor Switch (Water Temperature) Signals Shutoff at Low Temperature.

3. Oil Pressure Contactor Fails to Signal Shutoff.

4. Overspeed Contactor Switch Fails to Signal Shutoff.

5. Overspeed Contactor Switch Signals Shutoff at Low Speed.

Problem Checklist

Problem 1. Contactor Switch (Water Temperature) Fails To Signal Shutoff

Probable Cause

1. Incorrect Electrical Connections

Check connections to other components or install new wiring. See WIRING DIAGRAM for SELF-POWERED PROTECTION in the WIRING DIAGRAMS section.

2. Low Water Level in Cooling System

Fill the cooling system.

3. Incorrect Setting

Test operation (trip) temperature setting and if necessary install new contactor switch with proper setting. See Specifications.

Problem 2. Contactor Switch (Water Temperature) Signals Shutoff At Low Temperature

Probable Cause

1. Incorrect Setting

Test operating (trip) temperature setting and if necessary install new contactor switch with proper setting. See Specifications.

Problem 3. Oil Pressure Contactor Fails To Signal Shutoff

Probable Cause

1. Incorrect Electrical Connections

See JUNCTION BOX WIRING DIAGRAM for SELF-POWERED PROTECTION in the WIRING DIAGRAMS section for the correct wiring connections.

2. Incorrect Setting

Test and adjust contactor. If necessary install new contactor switch.

Problem 4. Overspeed Contactor Switch Fails To Signal Shutoff

Probable Cause

1. Incorrect Electrical Connections

Check connection, wiring and correct where necessary. See WIRING DIAGRAM for SELF-POWERED PROTECTION in the WIRING DIAGRAMS section.

2. Incorrect Setting

Adjust setting or install new contactor switch with the correct rpm range if necessary.

Problem 5. Overspeed Contactor Signals Shutoff At Low Speed

Probable Cause

1. Incorrect Setting

Adjust setting or install new contactor switch with the correct rpm range if necessary.

Mechanical Gauges For Temperature

To check these gauges, put the bulb of the gauge in a pan of oil. Do not let the bulb touch the pan. Put a thermometer in the oil to measure the temperature. Make a comparison of temperatures on the thermometer with the temperatures on the direct reading gauge.

Mechanical Gauges For Oil Pressure

To check these gauges connect the gauge to a pressure source that can be measured with accuracy. Make a comparison of pressure on the gauge of test equipment with the pressure on the direct reading gauge.

Contactor Switch For Water Temperature

Fabricated heat sink.2F7112 Thermometer.3J5389 Plug.8T500 Circuit Tester.

1. Make a heat sink as shown. Material can be brass, steel or cast iron. Drill a 17.8 mm (.70 in.) hole through the plate and use a tap to make 1/2 in. NPT threads.

2. Put marks on the two contactor wires that connect the contactor to the circuit. Disconnect the two wires.

Heat Sink [Dimensions in mm (in.)].

3. Remove the contactor and install a 3J5389 Plug. Install the contactor switch in the heat sink.

4. Put the heat sink and contactor in water as shown. Use blocks to support the heat sink at surface level.

5. Connect the 8T500 Circuit Tester between the wires that connected the contactor to the circuit.

Test of Contactor Switch
(1) 2F7112 Thermometer. (2) Fabricated heat sink.

6. Put the 2F7112 Thermometer in the water.

7. Use a torch to heat the water to the temperature range at which the contactor must activate. If the circuit test light does not come on within the temperature range given in the Specifications make a replacement of the contactor.

8. Let the water temperature go down. If the circuit tester light does not go out within the temperature range given in the Specifications make a replacement of the contactor.

Mechanical Overspeed Switch

6B344 Tach Drive Adapter5L8164 Tach Drive Adapter6V7800 Multimeter

1. Install 6B344 Tach Drive Adapter between the tach drive and the overspeed contactor. The 5L8184 Tach Drive Adapter must also be installed between the 6B344 Tach Drive Adapter and the overspeed contactor. The 6B344 Tach Drive Adapter provides a 1 to 2 increase drive ratio. The 5L8184 Tach Drive Adapter has a 1 to 1 drive ratio and is used only to provide clearance for the overspeed contactor.

2. Determine the overspeed setting using the chart shown. For rated speed not shown in chart, use 118% of rated speed ± 25 rpm.

3. Identify (for reassembly) and disconnect harness wires from C (common) and NO (normally open) terminals of the overspeed contactor. Insulate each disconnected wire with tape.

4. Reset the overspeed contactor by pressing the button on top of the overspeed contactor case.

5. Connect the 6V7800 Multimeter to the C and NO terminals of the overspeed contactor. Check for continuity. If there is continuity, replace the overspeed contactor.

Mechanical Overspeed Switch
(1) Lockscrews.

6. Remove the tag wire and loosen three lockscrews (1). Adjust the contactor all the way out by turning the contactor base CCW until the end of the screw slots are against the lockscrews.

7. Start the engine and, using an engine tachometer accurate to ±1%, run the engine to 1/2 of the overspeed setting rpm.

8. Adjust the overspeed contactor setting by gradually turning the contactor case CW until the overspeed contactor relay trips as indicated by a continuity reading on the 6V7800 Multimeter between the C and NO terminals. If the overspeed contactor is turned all the way CW and the multimeter shows no continuity, replace the overspeed contactor.

9. Tighten three lockscrews (1).

10. Shut off the engine. Remove the 6V7800 Multimeter from the overspeed contactor. Reconnect the harness wires to the C and NO terminals of the overspeed contactor.

11. Reset the overspeed contactor by pressing the button on top of the overspeed contactor case.

12. Restart the engine and observe the overspeed set point rpm by rapidly increasing engine rpm until engine rated speed is reached or until the overspeed contactor relay trips as indicated by automatic engine shutdown. If the engine automatically shuts down before the engine rated speed is reached, then proceed to the next step. If the engine does not automatically shut down before engine rated speed is reached, and wiring and connections are correct, then replace the overspeed contactor.

13. If the observed overspeed set point rpm is within ±12 rpm of 1/2 of the overspeed setting, then the overspeed contactor is properly adjusted. If the overspeed set point rpm is not within ± 12 rpm of 1/2 of the overspeed setting, then repeat the procedure starting with Step 3.

14. Shut off the engine. Remove the 6B344 Tach Drive Adapter and, if used, the 5L8164 Tach Drive Adapter from between the tach drive and overspeed contactor. Reinstall the overspeed contactor.

15. Install lockwire to three lockscrews (1).