Temperature sensor

[dbrody]

I just replaced the temperature sensor with a VDO 300 sensor; however, the temperature gauge is always reading low. What was the stock rated at? Is there a resistive curve somewhere on the sensors?

Dave

[craign]

Check this thread it might shed some light on the subject

http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=61422

[pokemon]

I tested the temperature sensor with an ohm meter.
Results:
at 20 degrees C ~115ohms (=abient temperature)
at 60 degrees C ~145ohms
at 100 degrees C ~200ohms (=hold sensor in boiling water for accurate results or run engine hot)

Connect one wire of the ohm meter to the wire connector on the sensor.
The other ohm meter to the sensor body or engine block.

You can replace your temp sensor with a 250ohm potentiometer and see if your temperature is still OK. Turn it from 0 to max resistance and the temp meter must follow from low to high temperature.
With the sensor disconnected the temp meter should go fully to the right hand side.

[pokemon]

One more idea...
Go to a car parts shop and take your ohmmeter and a lighter with you.
Explain your search problem and ask them a few sensors for testing.
Measure the sensor resistance at ambient temperature.
Heat the sensor with a lighter and measure the resistance again. It must have risen.
In this way you may find one sensor that matches with the resistance (ohm) figures given in previous reply.

[wastintime]

Dave,

I know this probably isn't the best suggestion in the world, but I danced around with getting my temp gauge too work too. When you say that yours is always reading low, how low does it read? How far will it sweep out when you run the engine hard? It really might not be a big deal. When I had my original temp sensor I only got the needle to the halfway point once.

As a lot of people on the forum have said, these aren't temp guages like the 911 had, so they're not too terribly indicative of what is actually going on in your engine. All you know is the oil temp where you're taking the reading. Granted, it is nice to know what your engine is doing.

Anyway, if the needle moves to a certain point once the engine is warmed up you could always just use that as your new reference point for normal operating temperature, and know that something wrong my be happening if the needle suddenly gets really hot. My gauge reads backwards, and I have a similiar reference point on mine. It's probably not the greatest, but whatever works....


Andrew

[dbrody]

I put in a 300F sensor which probably has a different curve than the one in there. The resistance data is great. Now I just have to figure out what the resistance is for the new sensor.

Dave