Water Temp Gauge

[Udi]

I have a Sunpro water temp gauge with a resistance type sender. The three connectors on the gauge are not marked. Is anyone else using this kind of gauge? I would appreciate it if you can tell me how the wires are connected.

Thanks,

Udi-

[Harry_S.]

Udi;

I don't have that make indicator but the back of mine looks identical to yours.
Mine is hooked up as your picture shows, left to right... sender- gnd- power.

Hope this helps you

[KenSandyEggo]

Udi, are you sure the marks aren't on the back of the instrument..under the mounting bracket? It looks like there are letters stamped into the back of the case. Sometimes they're very tiny, with just a "+" and "-" and "S" stamped near the posts.

[Udi]

Harry - is the second wire from the sender connected to ground?

Ken - the only markings that I could find were : MADE IN CHINA both on the instrument and the holder!

Udi-

[KenSandyEggo]

That's why stuff from China is cheaper. No instructions and no markings. :)

[Harry_S.]

Udi:

I have only one wire coming from the sender. If you have 2 wires...check the continuity of the wires. The wire that checks to the shell is the gnd. wire, the other goes to your indicator. Any good gnd. point will do.

[KenSandyEggo]

No-no, Harry. Any "good" ground point will NOT do for a water temp gauge. The water temp gauge is very persnickety. I had problems with spiking temps that drove me nuts (nuttier), until I contacted the manufacturer. I had a clustered ground. The tech told me that it is imperative that the water temp gauge have its own grounding spot and the closer to the battery, the better. I unclumped mine and gave it its own ground at the cable running to the battery and that was the end of the problems. Why the water temp gauge has this quirk is unknown to me, but it does.

[Udi]

The water temp sensor, Ken, is an RTD - a device that changes it's resistance with temperature. The temperature gauge is measuring the current that flows through this resistor. The current is a function of the voltage (ohm's low) that the resistor sees. So, to have an accurate reading, the sensor and the gauge must have the same "ground". Kapish? ;)

Udi-

[Harry_S.]

Yes, I remember you posting that on the old forum, Ken.

I agree the gauge itself would be better with an isolated gnd point. The sender has another gnd point. In my case, the sender has only one wire,that goes to the indicator, the shell is grounded to the engine gnd.

[KenSandyEggo]

Uuuuuuh...sort of Udi. So it wouldn't matter if it were clustered with other grounds as long as they were together? I can't really recall if that's how it was on my ship, but when I took the ground from the instrument and gave it its own spot, the problems ceased. I'll check it at the hangar today.

Harry, I know my sender only has one wire also and is most likely grounded somewhere at the engine area. Now I HAVE to take a look.

[KenSandyEggo]

Duuuuh. I have the little sensor with the disk that screws right into the water manifold as supplied by RAF, so it's grounded right there. A spade-lug slips over the disk to connect the wire to the gauge. I was thinking of my water temp and/or oil pressure senders I guess.