1989 mercruiser Aplha One. water temp senor issues

[george.caines]

Good day, everyone,

I was having water temp issues with my boat and figured out that it was the thermostat. I have replaced the thermostat with a 160° unit and it seems to be working. Although it is, I am running into other issues now. At idle or running a very low speeds, the temperature spikes quickly. Running at normal speeds the temperature settles at 160.

Attached is the picture of my thermostat unit. It has two locations on it for sensors. All the research I’ve done on these engines depending on the year, the sensors are in different locations and different styles. My question, is the sensor and a sensor sending unit what I am looking at? I cannot find any differentiation in any of the places I look. My best guess is that it is a temperature sensor on the top and a temperature sending unit on the bottom. Both of these are wired to the engine so I know they gotta be sending data somewhere.

Any information or recommendations would be greatly appreciated even if you know the part numbers that would greatly assist me in finding the parts.

 

[Scott Danforth]

one is the sending unit for the gauge, the other is probably an alarm.

 

[Bt Doctur]

usually with the housing facing up in a normal position the sender is stbd and the alarm is port