Alarm Systems
Engines are equipped with alarms in order to alert the operator if undesirable operating conditions occur. When an alarm is activated, corrective measures must be made before damage to the engine can occur.
Alarms are activated by critical operating temperatures, pressures, levels, or speeds. Table 1 lists the alarms that are available and the corresponding suggested setpoints. Some of the conditions that cause an alarm will also cause the engine to be derated. Table 1 also lists conditions that will cause the derating.
Note: Some of the alarms that are listed in Table 1 are optional.
| 3618 Engine Alarm Systems | ||
|---|---|---|
| Condition | Setpoint | Derating |
| Lubrication System | ||
| Low oil pressure (1) | 120 kPa (17 psi) |
No |
| Low oil pressure (2) | 320 kPa (46 psi) |
No |
| High crankcase pressure | 0.6 kPa (.09 psi) |
Yes |
| Oil filter differential pressure | 100 kPa (14.5 psi) |
No |
| High oil inlet temperature | 80 °C (176 °F) |
No |
| High turbocharger oil outlet temperature | 104 °C (219 °F) |
No |
| High main bearing temperature | 112 °C (234 °F) |
Yes |
| Excessive oil mist (3) | - | Yes (5) |
| Malfunction of the oil mist detector (4) | - | No |
| Metal particle detection (3) | - | No |
| Low oil level | Open contacts | No |
| Charge Air System | ||
| Aftercooler outlet air temperature | 50 °C (122 °F) |
No |
| Aftercooler inlet air temperature | 280 °C (536 °F) |
No |
| Inlet air temperature for the turbocharger | 45 °C (113 °F) |
Yes |
| Speed of turbocharger | 29500 rpm | Yes |
| Sea water | ||
| Low sea water pressure (1) | 30 kPa (4.3 psi) |
No |
| Low sea water pressure (2) | 140 kPa (20.3 psi) |
No |
| Cooling System | ||
| Low jacket water pressure | 70 kPa (10.2 psi) |
Yes |
| Low aftercooler pressure and low oil cooler pressure | 70 kPa (10.2 psi) |
Yes |
| High jacket water outlet temperature | 97 °C (207 °F) |
Yes |
| High jacket water inlet temperature | 90 °C (194 °F) |
Yes |
| High aftercooler and oil cooler inlet water temperature | 40 °C (104 °F) |
Yes |
| High jacket water outlet temperature | 70 °C (158 °F) |
No |
| Low coolant level (3) | Switch | No |
| Exhaust System | ||
| High cylinder exhaust temperature | 550 °C (1022 °F) |
No |
| High turbocharger inlet temperature | 650 °C (1202 °F) |
Yes |
| High turbocharger outlet temperature | 550 °C (1022 °F) |
No |
| Individual cylinder exhaust temperature | 50 °C (90 °F) |
No |
| Fuel System | ||
| High fuel temperature | 50 °C (122 °F) |
No |
| Low fuel pressure before the fuel filters (1) | 250 kPa (36.2 psi) |
No |
| Low fuel pressure before the fuel filters (2) | 450 kPa (65 psi) |
No |
| Low fuel pressure after the fuel filters | 260 kPa (38 psi) |
No |
| High fuel filter differential pressure | 70 kPa (10.2 psi) |
No |
| Starting Air System | ||
| Low starting air supply pressure (3) | 1034 kPa (150 psi) |
No |
| ( 1 ) | This setpoint is for an engine that is operating at less than 788 rpm. |
| ( 2 ) | This setpoint is for an engine that is operating over 788 rpm. |
| ( 3 ) | See the Technical Manual that was supplied with the engine or consult a Caterpillar dealer for information about the setpoints. |
| ( 5 ) | A derating for excessive oil mist is the decision of the chief engineer and/or the captain. |
| ( 4 ) | For information on the oil mist detector, see Service Manual, RENR2225, "Oil Mist Detectors". |
Engine Shutoffs
Shutoffs are set at more critical operating setpoints than alarms. Any problem that causes the engine to shut off must be corrected before the engine is restarted.
Table 2 lists the conditions and the recommended setpoints for the available engine shutoffs.
Note: Some of the shutoffs that are listed in Table 2 are optional.
| 3618 Engine Shutoffs | |
|---|---|
| Condition | Setpoint |
| Overspeed | 1186 rpm |
| Low oil pressure (1) | 105 kPa (15 psi) |
| Low oil pressure (2) | 260 kPa (38 psi) |
| High main bearing temperature (3) | 112 °C (234 °F) for 30 seconds |
| High crankcase pressure | 1 kPa (.15 psi) |
| Metal particle detection (4) | Both detectors activated. |
| Excessive oil mist (4) | Contact closed. |
| ( 1 ) | This setpoint is for an engine that is operating at less than 788 rpm. |
| ( 2 ) | This setpoint is for an engine that is operating over 788 rpm. |
| ( 3 ) | Rate of the rise in temperature |
| ( 4 ) | For more information, refer to the Engine, "Technical Information Manual" or consult your Caterpillar dealer. |
Procedure for Excessive Oil Mist
If an alarm occurs due to excessive oil mist, the engine will shut down. Then use the following procedure.
- After the shutdown, inspect the control system for other alarm conditions. Compare the timing of the shutdown to the activation of the alarm. Ensure that the shutdown was initiated by the oil mist detector.
Note: Instructions from the Service Manual, "Disassembly and Assembly" module will be necessary in order to perform this procedure.
Note: A sudden shutdown may initiate alarm conditions that do not indicate an actual abnormal condition. This may occur because the shutdown is uncontrolled. For example, a low oil pressure alarm can occur during an uncontrolled shutdown.
- Inform the chief engineer that the engine is unavailable.
- Inspect the display of the oil mist detector in order to ensure that the alarm is genuine.
If the detector is operating normally, the green "Ready" LED is ON and the red "Alarm" LED is FLASHING. The display will continue to indicate the percentage of opacity of the oil mist.
If the detector senses the oil mist during a fault condition, the green "Ready" LED is OFF and the red "Alarm" LED is OFF. The red "TEST" LED is illuminated and the red LED that indicates the fault is FLASHING.
- After verifying the cause of the alarm, shut off the air supply to the starting motor. This will prevent accidental starting.
- Open the manual valves for all of the cylinders.
- Activate the prelube pump.
| NOTICE |
|---|
The prelube pump should not be operated continuously for extended periods of time in the manual mode. If, during repairs, the prelube pump has run continuously for a period of three hours or more, it will be necessary to remove any oil that may have collected in the cylinders and/or above the valves. |
- Operate the barring device. If the flywheel will rotate freely, rotate the engine for two complete revolutions (720 degrees). Lock the barring device.
 |
Guards must be in place prior to operating barring device motor. Remove all hand tools prior to operating barring device motor. |
 |
| NOTICE |
|---|
Do not use an impact wrench to operate the barring device. The use of an impact wrench will cause gear tooth failure. |
- Deactivate the prelube pump.
- After the engine has been shut down for 15 minutes, remove all of the crankcase covers. The oil mist detector monitors each section of the crankcase. First investigate the section with the fault condition.
|
Flash fire may result in personal injury, if crankcase covers are removed within fifteen minutes after emergency shut down. Do not restart engine until cause for shutdown has been corrected. |
|
- Use a 123-6700 Laser Infrared Thermometer. Record all three temperatures for the small end bearing and for the large end bearing of each connecting rod. Record the temperatures for the front, the center, and the rear of each bearing.
- The temperature of any small end bearing should not exceed the average temperature of all of the small end bearings by more than 15 °C (60 °F). The temperature of any large end bearing should not exceed the average temperature of all of the large end bearings by more than 15 °C (60 °F).
Note: Lower temperatures can be expected for a shutdown during partial load operation.
- The maximum temperature of any bearing after full load operation should not exceed 112 °C (234 °F).
- Open and inspect the metal particle detector.
Note: It is important to measure the temperatures quickly, before the bearings can cool. This will provide the most accurate indication of the operating temperatures of the bearings. Step 10 can be efficiently performed by two people: one person measures the temperatures, and one person records the temperatures.
- Ensure that the large end bearings of the connecting rods can move freely. Normally, the rods can be moved slightly. Move the rods back and forth along the crankshaft journal.
- If the following conditions occur, perform Steps 12.a and 12.b:
- The temperatures are within the specifications that are listed in Steps 10.a and 10.b.
- A closer visual inspection shows no damage to the following components: pistons, cylinder liners, piston pins, main bearings and gear trains.
- Remove the oil filters. For instructions, see this Operation and Maintenance Manual, "Engine Oil and Filters - Change" topic (Maintenance Section).
- Cut the oil filters open with a utility knife. Inspect the pleats of the filter material for debris. The type of debris that is found will indicate components that require further inspection.
- The temperatures are within the specifications that are listed in Steps 10.a and 10.b.
- If the temperatures of the bearings exceed the specifications that are listed in Steps 10.a and 10.b, remove the components that are affected. Perform a full inspection of the components.
- When the engine is in satisfactory condition, perform a complete inspection of the oil mist detector. For instructions, see the literature that is provided by the OEM of the detector.
- Start the engine according to this Operation and Maintenance Manual, "Engine Starting" topic (Operation Section). Operate the engine at low idle rpm for ten minutes. If the oil mist detector causes another shutdown, repeat this entire procedure.
| NOTICE |
|---|
Do not operate the engine starting motor until the barring group pinion gear is fully disengaged from the flywheel ring gear. Serious damage to the engine could result. |
- After the engine has operated with no problem for ten minutes, stop the engine. Immediately remove all of the crankcase covers. Measure the temperatures of the connecting rod bearings. This will verify the correct operation of the engine.
- Resume normal operation.