[C320-list] Faulty Temperature Sender

[Dennis Cookson]

Our temperature gauge has not worked since acquiring our C320 last year, and fixing it has been on my to-do list for a while now. Today I finally managed to disconnect the wire that is normally attached to the sender and conduct a resistance test, which confirmed that it is open circuit.  Despite appearances, the sender body was making good contact with the engine ground.  Connecting the wire to ground swung the temperature gauge needle fully over, so both the wiring and the gauge are ok.

I don’t know if this temperature sender was an original fit by Catalina, or a subsequent addition, but it is plumbed into a T-piece that leads from the thermostat area to the water heater. It seems to be a relatively small device screwed into a brass adaptor, which in turn screws into the T-piece.  I’ve uploaded a picture here <https://c320.org/mediagallery/media.php?f=0&sort=0&s=20200623135307185>.

Can anybody help me identify this device, particularly the thread as I would prefer to do a quick swap to a new sender without draining the coolant. It looks like it will unscrew with an 11mm socket.  There is an article on c320.org <http://c320.org/> that mentions a Stewart Warner, 240-33 ohm device, but there are several different sizes. The suggested replacement on Catalina Direct doesn’t look much like the unit I have, but the notes suggest that it should have a metric thread.  But perhaps the adaptor converts the thread?

Grateful for advice,
Dennis Cookson
#577