My 1994 4 cyl. 40 h.p. Mercury is having cooling issues.
I had a short overheat warning a couple of trips ago. On the following trip, we ran her at full cruise power for three hours + and had no warning. The next one we had the horn almost continuously after running at full cruise power for 15 mins. and it continued even at low power. I changed the water pump, cup, and plate. The ground test went okay, but then we got the horn again while on the water. I disconnected the temp sensor on the powerhead, and the horn still sounded. Is that to be expected in a properly operating warning system, or should the horn go off when the sensor is disconnected? This model has no thermostat, so that's not the issue. Anyone have any suggestions?
I had a short overheat warning a couple of trips ago. On the following trip, we ran her at full cruise power for three hours + and had no warning. The next one we had the horn almost continuously after running at full cruise power for 15 mins. and it continued even at low power. I changed the water pump, cup, and plate. The ground test went okay, but then we got the horn again while on the water. I disconnected the temp sensor on the powerhead, and the horn still sounded. Is that to be expected in a properly operating warning system, or should the horn go off when the sensor is disconnected? This model has no thermostat, so that's not the issue. Anyone have any suggestions?