Hello,
I have a 16' Lund with a 2008 Mercury 25 HP 4 stroke that began sounding an alarm usually when trolling at its lowest engaged speed over the last three years. To solve this on the water I turn the motor off and then back on and that normally "solves" it for a while. Sometimes it simply doesn't happen at all. My neighbor suggested reviewing the issue on this forum prior to bringing it in to the local marina for service ($150/hr labor). Any help would be greatly appreciated. Here are the details:
1. This happens usually at very low speed, trolling for salmon/trout, however it will also sound occasionally while under way at higher speeds. The alarm is unbroken and the red warning light is illuminated.
2. When the alarm goes off, the water being pumped out of the motor is pretty hot. Hotter than I would imagine is "normal" and certainly hotter than when the alarm is not sounding.
3. The last professional maintenance performed on the motor was in 2013 as I don't use the boat a lot (approximately 3 weeks a year). From what I understand it's not particularly good to not use the motor this infrequently but that's the way it is at the moment (young kids, etc.). Additionally, this is only used in fresh water, not sure if that's a consideration. I had the motor tuned up and the impeller changed (suggested every 3 years). The mechanic mentioned there was an obstruction in the water line that he snaked to address the alarm at that time (I was a little skeptical).
4. When putting the motor away this fall, I ran it "dry" with treated fuel. There was not a lot of water was being pumped out of the motor (spitting, inconsistent stream) and the alarm sounded a few times.
5. Based on research, I'm seeing the following: bad impeller, deposits in the coolant system, heat sensor in head going bad, alarm module going bad, loose wires, and intermittent thermostat. I imagine there is a valve or switch that releases the coolant water when the motor gets to temperature that might be the problem.
Has anyone had issues like this with their Mercury and can provide some suggestions on how to approach diagnosing the root cause of the alarm and perhaps an approach to fixing it? I have the original owners manual which doesn't really address fixing things and a SELOC Repair Manual at hand. I am not a mechanic but am not completely motor ignorant.
Much appreciated!
C
I have a 16' Lund with a 2008 Mercury 25 HP 4 stroke that began sounding an alarm usually when trolling at its lowest engaged speed over the last three years. To solve this on the water I turn the motor off and then back on and that normally "solves" it for a while. Sometimes it simply doesn't happen at all. My neighbor suggested reviewing the issue on this forum prior to bringing it in to the local marina for service ($150/hr labor). Any help would be greatly appreciated. Here are the details:
1. This happens usually at very low speed, trolling for salmon/trout, however it will also sound occasionally while under way at higher speeds. The alarm is unbroken and the red warning light is illuminated.
2. When the alarm goes off, the water being pumped out of the motor is pretty hot. Hotter than I would imagine is "normal" and certainly hotter than when the alarm is not sounding.
3. The last professional maintenance performed on the motor was in 2013 as I don't use the boat a lot (approximately 3 weeks a year). From what I understand it's not particularly good to not use the motor this infrequently but that's the way it is at the moment (young kids, etc.). Additionally, this is only used in fresh water, not sure if that's a consideration. I had the motor tuned up and the impeller changed (suggested every 3 years). The mechanic mentioned there was an obstruction in the water line that he snaked to address the alarm at that time (I was a little skeptical).
4. When putting the motor away this fall, I ran it "dry" with treated fuel. There was not a lot of water was being pumped out of the motor (spitting, inconsistent stream) and the alarm sounded a few times.
5. Based on research, I'm seeing the following: bad impeller, deposits in the coolant system, heat sensor in head going bad, alarm module going bad, loose wires, and intermittent thermostat. I imagine there is a valve or switch that releases the coolant water when the motor gets to temperature that might be the problem.
Has anyone had issues like this with their Mercury and can provide some suggestions on how to approach diagnosing the root cause of the alarm and perhaps an approach to fixing it? I have the original owners manual which doesn't really address fixing things and a SELOC Repair Manual at hand. I am not a mechanic but am not completely motor ignorant.
Much appreciated!
C