Cruising for some comments: My boat has three 4 components associated with water temperature: temp gauge, temp sender, temp. switch and thermostat. While running under high load (4000-4500 rpm) temp gauge reads 175 deg consistently. At the same time, I get intermittent alarms which I had suspected were due to engine temperature. I took out the sender and the switch and tested both. For the sender, the manual shows a table that has resistance readings that should correspond to temperatures:. at 140deg F-121to147 ohms, 194 deg F- 47-55 ohms, and at 212deg F-36-41 ohms. At 212 deg F, the lowest resistance reading was 55 ohms. The manual says to replace it if any of the readings are outside the ranges shown in the table, so I conclude (sort of) that I need a new sender. I also checked the temp switch (part 48952) and it appears to be ok. The switch is supposed to close at 190-200 deg F. It closed at a little higher than 200, more like 210 but that could have been due to my water bath setup causing some inaccuracies. I haven't checked the thermostat yet. Would like to hear from anyone that knows about this system, particularly whether or not what I have described would cause me to get alarms while running.
