Temp Sender Testing?

[Bob Baird (39424)]

Hi all,

I have a 1960, but the question should apply to any temperature sender. I have the original sender and a redone gauge. The temp reads about 145-150 max. I want to try various senders, but it would be nice if there were a way to test them in some way first without having to install them one at a time and heat up the engine.

So, is there some simple test, resistance, etc., so that I can at least narrow a larger number of senders to a smaller?

Thanks,

Bob

[Larry Linder (22779)]

Re: Temp Sender Testing?

A few years ago I ran several tests on a batch of sensors, new, nos, junk yard finds and several orig. that read correctly in orig. cars.

A dozen were suspended from a set of brass rails and partially immersed in a water bath, heated, and an every 10 degrees the resistance of all were read. The data was plotted and compared to the orig. spec. control drawing.

The goal was to see if you could measure one cold or at a known temperature of your hand, approx 94 deg. and be able to predict how the sending unit would work at 160, 180, 200 deg F.

The conclusion was that the slope resistance / deg F of the internal thermister was so great and had such a wide variation that - we conclued that it would not give you an indication of the sensors resistance at temperature.

So before you toss the sensor suspend it in water bath, SS cook ware on the stove and measure the resistance at 180 deg. Using a good digital ohmmeter. The sensors are filled with an oil to thermally connect the thermistor / brass shell. DO NOT imerse the sensor or you may find you have lost the oil and replaced it with water.

If you would like to view the results I can post them for you all to view. They are not in a condition to publish but the data is there and a set of plots of the data.

You can look at the values and substitue a 2 watt resistor of that value and check operation of the gauge.

I have heard of a lot of hokey schems to add resistors both in series and paralle to make the instrument read correctly with a particular sending unit but it easir to sort a bunch of Junk Yard devices, clean and install a working sending unit.

Make sure that you do not use teflon tape or other selers when you install the sending unit as this gives you very eratic readings.

Look at the data and make your own conclusion.

Hope this helps and if you test a few send me the data.
Thanks.

[Bob Baird (39424)]

Re: Temp Sender Testing?

Larry,

Would love to see the data!

Thanks,

Bob

[Dick Whittington (8804)]

Re: Temp Sender Testing?

I do not have my CD with me right now, but in an earlier Restorer there was an article on the temp senders. Maybe some one will come up the the Vol and issue #

[Donald Ling (31176)]

Vol 16 #2 *NM*

[Larry Linder (22779)]

Re: Vol 16 #2

The article said a lot but there was a lot it didn't say - that is why we did the testing. There is a vast difference between a spec. control print / analysis and actual testing of real units. The prints were used to control product but the vender understood what was necessary to make it work and prints at local plants had mods to them that never got back to Chevrolet.

[Larry Linder (22779)]

Re: Vol 16 #2

Send me your E-Mail address to ljlinder@sbcglobal.net and I will send you a copy in what ever foram you would like. The orig was done in StarOffice and can be written as a .doc so you can suck it in. I can send you a .pdf so you can view it as we intended it to be viewed. I don't know if the translator copeis the graphs correctly.
See what you think?