My brother and myself recently bought a new hull and fitted our existing engine onto it. The engine is a 1996 Mercury 200 offshore carb'd motor that I bought from a friend who was a fishing guide. The engine has had one fishing season on it since being rebuilt due to a ring coming apart in one cylinder so he had all 6 cylinders redone with new pistons and rings since it was already apart and the extra labor was minimal. Before installing the engine, I changed the oil hoses from the remote tank to the engine tank, changed the clear oil hoses from the oil tank to the oil pump and from the oil pump to the fuel line it injects into. We also put in new voltage regulators since one had failed as well as all new water lines under the cowl.
We had the boat out yesterday and had been idling through no wake zones on a river and suddenly the oil alarm went off out of nowhere.
We shut the boat down and the river current helped us drift out of the middle of the water way. After pulling up to the bank and pulling the cowl off, nothing obvious was wrong. No oil leaks, oil in both reservoirs and the heads were cool to the touch. So we fired up the engine and once again the oil alarms started going off. Since it was still smoking and was obviously still burning oil, we revved the engine up and the alarm would shut off at around 1200 rpms. If brought back down to idle, the alarm would come back.
Since we were only a short way back to the launch, we ran back, keeping the rpms up and had no alarm until once again idling at the launch to put the boat back on the trailer.
Once getting home, I started searching online for the symptoms which could be:
1) float in the engine mounted oil tank has gone bad and is sounding a low oil alarm
2) the oil pump isn't turning and the rotation sensor is doing its job
3) the module is going out and not doing its job
Since the cap has the float installed on it and is new due to the old cap cracking, I doubted it was the problem. I verified it wasn't by checking continuity on the wires while moving the float and the contacts opened and closed as they were supposed to.
I figured the oil pump was turning since the engine was still smoking like normal and we could get the alarm to go off, but I wanted make sure all was well after reading about the drive gear to turn the oil pump shaft being nylon and possibly failing and having bad spots. So, I pulled the oil pump and drive shaft and inspected everything, and here is what is inside:
and here is a video of that worm gear turning after pulling all the plugs so I could turn the engine over by hand:
All of the teeth looked fine. While there was a little slop between it and the gear it drives, it wasn't stripped by any means.
Here is what goes into the hole and the oil pump attaches to:
That bushing with the black dot has the magnet in it that makes the rotation sender put out the 5 volt pulse to let the module know the oil pump is turning. The original bushing had some wear marks and the local Mercury dealer had one on the shelf for $16 so I went ahead and installed a new one in case the magnet had failed or become weak. Part number is 41429A2.
I fired the engine back up and still had the oil alarm go off while cranking and continuing while the engine was running. Since I am running it at the house now with earmuffs to supply water, I can definitely tell it is getting oil and has the normal amount of blue smoke coming from the prop.
I get back online and keep reading and see that the white wire coming from the alarm module going to the rotation sensor should have 12V going to the rotation sensor. I put my meter on it and it has 2V with the key on and 3V with the engine running. So now it is looking like the module is to blame, which I read is fairly common. Part number on the boat is 41470A23
I hook up a jumper wire to the white wire's barrel connector and give it a quick tap the positive battery lead on the solenoid and it doesn't spark, so I clip it to the solenoid and start the engine and now there is no oil alarm!!!!
I pulled the wire off of the solenoid expecting the alarm to sound again and it doesn't......
I put my meter back onto the white wire and it is now sending 9V to the sensor. I don't know if back feeding 12V woke up a failing component or what, but now alarm has stayed off for several rounds of cranking and running. While it only has 9V going to the rotation sensor, I guess that is enough to make it work. I double checked by completely disconnecting the white wire the alarm did sound again. As soon as I hooked the white wire back up, the alarm silenced.
I am still ordering a used, more recent model number 41470A26 on ebay to be sure all is well.
Hope this helps with anyone else who has this issue come up.
Robert
We had the boat out yesterday and had been idling through no wake zones on a river and suddenly the oil alarm went off out of nowhere.
We shut the boat down and the river current helped us drift out of the middle of the water way. After pulling up to the bank and pulling the cowl off, nothing obvious was wrong. No oil leaks, oil in both reservoirs and the heads were cool to the touch. So we fired up the engine and once again the oil alarms started going off. Since it was still smoking and was obviously still burning oil, we revved the engine up and the alarm would shut off at around 1200 rpms. If brought back down to idle, the alarm would come back.
Since we were only a short way back to the launch, we ran back, keeping the rpms up and had no alarm until once again idling at the launch to put the boat back on the trailer.
Once getting home, I started searching online for the symptoms which could be:
1) float in the engine mounted oil tank has gone bad and is sounding a low oil alarm
2) the oil pump isn't turning and the rotation sensor is doing its job
3) the module is going out and not doing its job
Since the cap has the float installed on it and is new due to the old cap cracking, I doubted it was the problem. I verified it wasn't by checking continuity on the wires while moving the float and the contacts opened and closed as they were supposed to.
I figured the oil pump was turning since the engine was still smoking like normal and we could get the alarm to go off, but I wanted make sure all was well after reading about the drive gear to turn the oil pump shaft being nylon and possibly failing and having bad spots. So, I pulled the oil pump and drive shaft and inspected everything, and here is what is inside:
and here is a video of that worm gear turning after pulling all the plugs so I could turn the engine over by hand:
All of the teeth looked fine. While there was a little slop between it and the gear it drives, it wasn't stripped by any means.
Here is what goes into the hole and the oil pump attaches to:
That bushing with the black dot has the magnet in it that makes the rotation sender put out the 5 volt pulse to let the module know the oil pump is turning. The original bushing had some wear marks and the local Mercury dealer had one on the shelf for $16 so I went ahead and installed a new one in case the magnet had failed or become weak. Part number is 41429A2.
I fired the engine back up and still had the oil alarm go off while cranking and continuing while the engine was running. Since I am running it at the house now with earmuffs to supply water, I can definitely tell it is getting oil and has the normal amount of blue smoke coming from the prop.
I get back online and keep reading and see that the white wire coming from the alarm module going to the rotation sensor should have 12V going to the rotation sensor. I put my meter on it and it has 2V with the key on and 3V with the engine running. So now it is looking like the module is to blame, which I read is fairly common. Part number on the boat is 41470A23
I hook up a jumper wire to the white wire's barrel connector and give it a quick tap the positive battery lead on the solenoid and it doesn't spark, so I clip it to the solenoid and start the engine and now there is no oil alarm!!!!
I pulled the wire off of the solenoid expecting the alarm to sound again and it doesn't......
I put my meter back onto the white wire and it is now sending 9V to the sensor. I don't know if back feeding 12V woke up a failing component or what, but now alarm has stayed off for several rounds of cranking and running. While it only has 9V going to the rotation sensor, I guess that is enough to make it work. I double checked by completely disconnecting the white wire the alarm did sound again. As soon as I hooked the white wire back up, the alarm silenced.
I am still ordering a used, more recent model number 41470A26 on ebay to be sure all is well.
Hope this helps with anyone else who has this issue come up.
Robert