Installing an engine temp sensor - Yanmar 4JH3

[papawads]

I have the -TE model version of this engine, which comes with a coolant temp switch (to alarm at overheat) but not a temp sender, to warn you beforehand    All other versions have both but…. have exactly the same water pump & thermostat housing.

As the attached diagram shows, the location of the temp sender is shown.  My problem is, that’s exactly where my coolant hose attaches,  to warm the hot water cylinder in the saloon….

I’d love to know how others have this configured to have both temp sender, temp switch AND hoses to/from the hot water cylinder.

many thanks
Papawads

note on pic…. #22 is the existing switch, red circle is around (would be) temp sender, blue lines are my hoses.



OK: now 3 hours later, and a large coffee.  Having pulled off the coolant pump to service it, I might have the answer…. But would really  appreciate confirmation.

These photos show another threaded access point to the pump housing, which is NOT visible on the Yanmar parts diagram.  Potentially I take this out and replace the current plug with the sensor?

It’s possible my hoses running to the water heater are in the wrong place!

Thoughts most welcome 🤗 

[zaphod]

It looks like the port with the plug in it is where part 22 on the diagram is supposed to go.

Notice how it shows part 22 going in on an angle similar to the unused port?

[dbostrom]

Papawads, we have the 3JH3 (3/4ths of 4JH) and successfully used the proposed port in your last photo for an analog sensor retrofit. 

[mic98034]

What are the threads of that plugged port?  (so I can make sure to buy a compatible water temp sender)