Oil temp sending unit

[Patrice Belkowiche]

Hello,
I am looking for an oil temperature sending unit 6 volts for my 356c year 1964.
Thank you for your help.
Pat

[Doug McDonnell]

If you can find an old sending unit you may be able to use it. The other alternative is to have your gauge recalibrated to a new sender by a vendor in my understanding. See this link: viewtopic.php?f=1&t=41942&hilit=oil+temp+sending+unit

[Patrice Belkowiche]

Thank you Doug.
I would like to find an used one so I don't have to recalibrate.
Kindly
Pat

[Patrice Belkowiche]

I just found an used one on eBay.
Thank you for your help.
Pat

[Wes Bender]

Check the calibration on the used one when you get it. Check it in boiling water. Make up some jumper wires to connect it to the car's wiring in the engine compartment.

Wes

[Patrice Belkowiche]

@ Wess,
Why jumper cables. I was thinking to hook it directly after checking if its working.
About calibrating i am going to check out with my thermometer gun if its accurate. I made the same way for a friend and it was good.
Thank you
Pat

[Wes Bender]

Jumper cables only to get the sensor from the engine compartment into the pot of boiling water. What are you going to point the thermometer gun at to read oil temperature? A dipstick thermometer would a better source of accurate oil temperature.

Wes

[Mike Horton]

Pat, the known boiling point of water, is typically used as a calibration standard, by which to determine the relative accuracy of the pair...

[Brian R Adams]

Point the IR sensor gun at the oil junction block atop the case, that's where the temperature sensor lives and samples, downstream from the oil cooler. The sump oil will be 15 - 30 degrees (f) hotter when the engine is well warmed up.

Boiling point of water varies with atmospheric pressure, but unless you are in the eye of a hurricane, or very high in the mountains, it will get you close enough. You can always dip a cooking thermometer (or the Mainley) in the water to check it.

[Larry Coreth]

Patrice et al,

Having done this before, let me suggest the following:
1. note on the indicator face (both with and without numbers) there should be a very light mark which indicates 100°C/ 212°F (water boiling at sea level, subtract 1°F/500ft.in elevation). If this mark is not discernible it is mid way between each end of the "green zone". .
2. In a small pot made of alu. or steel with no coating inside or out, fill half full and bring to a rolling boil.
3. take pot to car where the temp sender has been removed but still electrically connected,
4. set sender in the water and be sure it makes contact with pot bottom and pot is grounded to motor
5. Turn on ignition switch to "on", note gauge reading.
This will be boiling temp, +/- a degree or so which is not significant for our needs.
Note also that although the water has stopped boiling when removed from the stove it is still at 212°F and will hold this temp for several minutes.
If the gauge indicates way off of center this will require some more specialized help.

BTW does your old sender not work at all ?

[Dave Wildrick]

According to Joe Leoni, the original 6V temp sender should read about 28 ohms at normal room temperature, about 74 F:

[To: 356talk@356registry.org <356talk@356registry.org>
Date: Sunday, July 09, 2000 12:44 PM
Subject: testing temp. sender

The sensor in the tool box, will read about 28 ohms at 74 F.
This is the temp in my garage this morning.
I think in our books we say 7 ohms at 20C.

However if you have had the Oil Temp conversion with the reverse
sensor all bets are off. Brad (NLA) is the expert in this area.

Hope this helps.

Joe
356 Electrics]

[Greg Spreeman]

Trying to figure out how this part of the car works so, forgive any missteps. I took my tester, turned on the ignition switch to send power to the gauges, etc. Went to the back of the car and tested the temp sensor. Had to use it at 200 ohms setting, doesn't go any lower. My multimeter shows 69.9. What am I doing whacky?

[Wes Bender]

Turn the switch off. You don't need power to check the resistance of the sensor. Remove the lead from the temperature sensor and then measure the resistance from the electrical contact on the sensor to ground. As Dave indicates above, the sensor should read about 28 ohms at 74 degrees (room temperature).

[Greg Spreeman]

That might be the issue. I am reading some 19 ohms.

[Glen Getchell]

Using boiling water is not an accurate test, and will read low. An accurate measurement of water temp takes a much more complex setup than a thermometer in a pan. That is because just because the water is boiling it’s not all the same temperature. And the steam bubbles themselves act as an insulator. A boiling stone would help. Boiling stones or chips make more even boiling and prevent superheating. All they are are like chips of broken porcelain. But you would still get a much more accurate reading by heating a pan of oil with the sender and a trusted thermometer as the oil will not boil or evaporate.

Glen
64Cx2