flight systems
Flight Systems Engine Saver Troubleshooting
A number of Engine Savers have recently been sent to us for repair. Upon inspection it seems that there is nothing wrong with a large number of them. Regardless of the “fault” indicated by service personnel, the only real problem seemed to be incorrect calibration or poor adjustment of trip points.
These units were not new, and were obviously operating correctly for many months prior to their return. The conclusion we have come to is that the setting had been changed, resulting in the “fault” indication being incorrectly displayed. This suggests that service personnel do not fully understand the equipment. They may not be aware that a simple visual inspection of the unit will tell them whether or not the system is functioning correctly.
In the past similar problems were encountered, and a document detailing visual inspection procedures was circulated. Consequently, the failure list dropped alarmingly. The document has been reproduced for your benefit, as it could save your operation a lot of time and expense. Better surveillance also means that with a more accurate fault diagnosis, the Engine Saver will do the job it was installed to do.
The following should be kept in mind before conducting a visual inspection:
- The Engine Saver is precision equipment. It requires sensible study of the manual before making any setting changes.
- Operation of the Engine Saver is almost totally RPM driven. Therefore, the unit must be calibrated to the RPM signal. If this is done incorrectly, there will be faults in pressure and other settings. The calibration procedure is described in good detail in the manual. It can be set from the vehicle engine using the coarse and fine dials and a voltage reading from a multi-meter. RPM can be provided from different sources but ideally using a magnetic pick up against the engine ring gear on the flywheel. This is fairly standard on large diesel engines.
- Program switches MUST be selected to suit the RPM source. This again is detailed in the manual.
- Ideally, the Engine Saver to be HOT-wired, although this is not mandatory.
GUIDELINES FOR VISUALLY CHECKING OR RESETING AN INSTALLED ENGINE SAVER
An Engine Saver displays what is happening to an operating engine with a series of RED & GREEN LED’s. The internal presentation is regarded as diagnostic and the external presentation displays fault conditions that have been identified.
With the engine stopped, open the device door and look inside. Because there is NO pressure in oil and coolant circuits, RED LEDs will be illuminated on their respective electronic module sections. These indications are exactly as they should be.
A yellow LED on the outside of the door indicates power is ON to the unit. A problem can be indicated by a GREEN LED on the ENABLE section of the electronic module. This Green LED will be matched by a YELLOW LED on the OUTSIDE of the DOOR. This Yellow LED will illuminate 10 seconds after the internal GREEN illuminates and shut down action is called for. This will have happened while the engine has been stopped. The Engine Saver will have to be reset before the engine can be started.
In this case, the engine idle speed setting is incorrect. This can be corrected by sufficiently increasing the engine idle speed setting on the internal enable dial, such that the internal GREEN LED is turned off.
This particular exercise has set the ENABLE point for all subsequent checks. It has also demonstrated that the Engine Saver is functioning as required.
PLEASE NOTE that in all fault checks the Engine Saver has to be ENABLED to take programmed action. There is, however, an exemption in the event of engine Overspeed. Programmed action will take place, 0.5 sec after the Trip Point is exceeded.
An Overspeed Trip Point will have been nominated by the engine manufacturer (probably in the order of 2000+ RPM), and this can be simply set on the RPM dial. If you are not satisfied that it doesn’t trip at normal full throttle approved speed, you can increase the Trip Point slightly.
The Oil Trip Point should be set next. It is important to keep in mind that RPM speed against pressure is a lineal display, but fuel pump speed against pressure is a curve. This curve can vary in two different machines even with the same model. The following procedure should be followed to allow for this.
Firstly, set the oil pressure Trip Point. Run the engine at 900 RPM and set the dial to about 5PSI. Then turn the idle dial up until the Red LED illuminates. This is the Trip Point for the engine at 900 RPM. Add +10% and set the number on the Idle Dial. Increase engine RPM to 1800RPM. Using the RUN adjustment find the 1800RPM trip point and add +10% for the setting. (To avoid future FALSE TRIPS, make sure that the run trip points +10% is always above RADIATOR CAP pressure).
Next set the coolant pressure Trip Point as per the method for oil pressure above. Here, the source of coolant pressure is the coolant pump and the pressure is measures at the pump outlet. This is a very sensitive detection condition, meaning even the smallest deviations from normal will be detected. Common gauges are never this effective.
Finally, Run The Engine From Idle To Full Throttle.
Note that nowhere in the speed range does a red led illuminate. If it does so even for a brief second, adjust idle and run trip points to correct the settings.
Also note that when the engine is at low idle, the enable speed led is off and the low oil pressure led is on. as the engine accellerates, the oil pressure led goes off and the enable led comes on. This is the rule for all operation.
Assuming that an enable LED and a low oil or coolant pressure LED are illuminated together, a trip situation is set up in 10 seconds. Regardless of whether the engine is running or has been shut down, the trip condition will operate as programmed. This means that the Engine Saver will have to be reset before the engine can be restarted. The external fault indication will still show that the shutdown was due to low oil or coolant pressure but there will be no indication that the fault was due to incorrect setting
The above procedure details how to set the oil and coolant circuits to benefit from the Electronic Ramp built into your Engine Saver. (The procedure is exactly the same for coolant) It provides a valuable means of visually checking oil and coolant surveillance, since it is possible for the surveillance mechanism to be faulty without anyone realizing.
It is advisable to develop the habit of looking inside the door at regular intervals. Although one should not regard this as an invitation to start adjusting settings.
Remember, with overspeed, oil and coolant monitoring the system is fail safe. In the event of the RPM source failing, the overspeed LED on the FAULT LED will blink to indicate that the circuit is not working and must be investigated.
Also, oil and coolant transducers will blink their respective circuit LEDS, indicating they are in Open Circuit mode and reading permanent high pressure.
It is also important to make these adjustments when the engine is at normal operating temperature. The difference between HOT and COLD settings can affect circumstances.
Having set Trip Points for overspeed, oil and coolant one can proceed to other trip point settings. Having checked calibration and program switches, the dials on the electronic module can be regarded as REAL numbers. If a Trip Point of 80 degrees Celsius is required, then the dial can be set at 80. This will be the Trip Point.
Crank case pressure is still a fixed pressure switch with a Trip Point of 10” W.G. It is a very accurate switch. As an alternative, other switch valves up to 15” WG can be provided if required.
The Level 7C model engine saver has provision for an additional module permitting the fitting of an adjustable transducer for monitoring crankcase pressure. In certain circumstances, this is a very useful option. Such as monitoring deterioration of crank case pressure, thereby extending service life.
The function of the Turbo Boost switch has been expanded from the original Engine Saver to include duties such as providing an RPM back up for oil and coolant. It is a 15” WG switch and when it is on line, a GREEN LED illuminates on the Electronic Module. It is difficult to test this in a low RPM condition but can usually be tripped by stalling the converter with the machine stationary.
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