Coolant temp sensor removal - C28 Cutwater?

[JonR]

I'm going to be more direct with my question instead of it being buried in an older post on the subject in the hope that someone has done this before and are able to provide insight.

I have determined that I have a bad coolant temp sensor on my D4-260 Volvo/Penta engine. I have found it's location on the engine as well. Access would be fairly easy except for the mounting of the main engine computer and a mounting bracket for several electrical connections. All are on the starboard side of the engine. I have a simple question: Are there any gotcha's associated with unbolting these things for easier access to the sensor? I have the new OEM sensor already.

Sincerely,
Jon R.

 

[JonR]

So, I guess I will now answer my own question: To get to the coolant temp sensor, I suggest that you disconnect both the electrical connector mounting bracket and the main engine computer. Once these are out of the way, the temp sensor is easy to access. I was able to change it without loosing much coolant at all.

I knew I had a faulty temp sensor when I saw readings as low as 29 degrees F in August. It would read erratically and then, suddenly it would read 185 degrees, the normal operating temp. Ironically, I also had another issue affecting the temp at the same time. When it did read correctly, there was an issue where, when I went over 7 or 8 knots, I'd get a rapidly climbing temp and then a temp warning. I couple things I also noticed, my raw water washdown pump would not work well with the engine running. Additionally, I could not get my toilet to 'prime' when the engine was running. All of these are fed from the same strainer outlet. I made me thing the engine was being stared for cooling water. I checked the strainer and, while there was some eel grass in it, cleaning it had no affect. Since I was also in need of new zincs, I had a diver come out and replace the zincs and inspect the raw water intake. It was almost totally blocked with eel grass. The overheat problem has totally gone away since clearing the raw water intake. I now carry a tool for clearing drains, I water jet which balloons to seal the entrance, that I can use to blow out the raw water intake if the situation arises again. Simply close the shutoff, insert the tool, and, simultaneously open the valve and turn on the hose to clear the block. Close the valve, replace the strainer, and you should be good to go - hopefully 🙂.