testing Water temperature sender


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By MoonShadow - 13 Years Ago
I want to test some single wire temp senders that I have out of the car. Is there an Ohm reading that would indicate if the sender is good or faulty? Chuck
By Y block Billy - 13 Years Ago
Don't know what the ohm reading is as I am at an airport, but when you find out, hold a lighter to it while the meter is hooked up and make sure it changes.
By bergmanj - 13 Years Ago
What year system are they out-of?  '54 & '55 were King-Seeley 6-V, and '56 was King-Seeley 12-V; none of these is at all compatible with earlier or later systems!  They use a "different" hot-wire, points, and bi-metal sensor which you CANNOT test the same way as other resistant-dependent systems!!!

The very best way to test them - IF they are any of the above type - is to substitute them into a known-good complete system: Resistance measurement alone WILL NOT tell you what you want to know.  Resistance-only measurement will only tell you a specific set resistance of the internal hot-coil just until the points open, then you will read "open" until it closes again, at which time it will again read only the fixed coil resistance.

Search back for some of my previous posts on this very subject for details.  Otherwise, you will probably throw-away perfectly good senders due to misunderstanding how they are designed to work.

Regards,   JLB

By MoonShadow - 13 Years Ago
Thanks for the responses. Mine is in a 56 Victoria. The one in the car seems to be bad and I've collected several in my stash over the years. I wanted to make sure one of them was working before draining the radiator and making the swap. Knowing how to id the 55/56 will be helpful. Thanks again, Chuck
By bergmanj - 13 Years Ago
Moonshadow,

It's been a while - so I don't remember specifics anymore; but, I've carefully opened-up one of the temp. sensors, cleaned the points (they're usually the problem / burnt or corroded), re-calibrated it (very small spring-tension calibration screw inside - to mid-point on the matching gauge while sensor is in boiling water); then, sealed it back up with soft solder.

Thought that someone here might be interested.

Regards,   JLB