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Oil temperature gauge


Froc

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Hi all,

I have a Vitesse with an oil temp gauge fitted. The sensor for the gauge was in the oil filter adaptor when I bought the car, and the gauge didn't seem to work (it just flickers around zero. Doesn't ever get to 30c, the minimum reading on the gauge).

The car came with a sump plug oil temp sensor. I fitted that, and connected it up, expecting that it would give a stronger reading from that position, but it has made no difference to how the gauge behaves.

With the ignition on, I have earthed the sensor wire, and the gauge reads maximum, so I know the wiring and gauge are ok. Basically, I am stumped. Either both the sensors (sump and oil filter location) are broken, or I have missed something. Any ideas?

Cheers

Froc

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While in ourcars the sensor will have one wire, moderns have two, or even three!   So check that compatibility.

 

Then, use a multimeter to check the sensor function.

Measure the resistance of the sensor, between the connection and earth.

As the temperature rises from cold, that will either rise or fall, depending on what type of sensor it is.

There are two types of temperature senders, negative and positive coefficient types (NOTHING to do with electrical polarity!)

A Smith's or Jaeger's gauge expects a negative sensor, whose resistance falls as temperature rises.

 

Here is the chart of a WATER temperature sensor that I tested.   A new, correctly working sensor is shown in purple, but the blue and yellow responses are from old sensors.

I suspect that an oil temperature sensor will have the same range response.

 

post-139-0-96753700-1453630833_thumb.jpg

 

If your sensors show the smooth decline as the engine warms up, then they are working, but as you have excluded problems in the wiring, I suspect they won't.

JOhn

 

 

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