posted 04-05-2006 09:07 AM ET (US)
While there is a replacement system for the entire oil injection mechanism on your Mercury motor, I do not believe there is an after market substitute for the electronic alarm module. They are expensive, too! And from a small sample of owners that I know, that module seems to need frequent replacement. Two out of two owners with that module in their older Mercury motors have replaced it.The alarm module on your Mercury motor connects to three sensors:
--cylinder head temperature sensor
--oil reservoir float switch
--motion sensor in the drive shaft for oil mixing pump
The first two sensors are just simple electrical contact closures, I believe, and it would not be particularly difficult to just have them signal an alarm directly.
The motion sensor is a magnetically actuated signal which detects the motion of the input shaft turning the mixing pump. The shaft has a a steel driven gear which is operated by a plastic drive gear clamped around a crankshaft journal. The plastic gear rotates at crankcase speed, and the gear reduction is very high, so the pump shaft turns much slower. The steel driven gear is coupled to a plastic shaft. This has a magnet set into it and glued in place. The spinning of the magnet poles produce an electronic signal from a sensor.
The plastic gear is in the crankcase area, and its only lubrication is from the oil carried into the crankcase with the fuel. If the engine temperature rises, as in a overheat condition, the gear is also subjected to temperature stress.
The electronic signal from the sensor is connected to the alarm module. The alarm module also receives pulses from the ignition module. The frequency of the pulses from the ignition and motion sensor are compared. If the ratio falls below a threshold level, the alarm module sounds an alarm.
This motion sensor was added to the system to detect failure of the plastic drive gear. Failure of the plastic drive gear was previously undetected, and it would cause loss of oil pumping and subsequent engine failure. The Mercury alarm system has no sensor which actually detects flow of oil. Thus it has no way to detect "starvation" of the oil, as you mention. It just detects two conditions: reservoir full, and input shaft moving.