I am trying to diagnose if my oil temp sender is working.

I took a reading on the 20k scale, at room temp and got 1.8 1.9 ohms

Put a little heat on it with propane torch for a few seconds and the reading is .003 - .004 ohms

Funny thing is the meter will jump around a lot particularly if I slide the lead up and down the length of the sensor tip.

Do anyone know if this resistance seems like the sensor is working or not?

My gauge wasn't reading anything so i started with this as I was doing an oil change.

wiring from the sensor to the gauge reads as good.

Grounding green wire terminal on gauge makes needle peg tot he right.

So I am thinking the sensor is bad, is my thinking correct?

Google:

site 914world.com oil temp sensor resistance

http://www.914world.com/bbs2/index.php?showtopic=97987 here ya go. found some information regarding the temp senders.

trying to figure this out.

I checked 3 different sensors that I have and a see resistance drop on the sensors when I apply heat from a torch. So I assume the sensors are working.

I took the wire going to the senor under the car and grounded it and the gauge pegs.
So I assume the wiring to the gauge is good.

I plugged a sensor into the wire and applied heat from a torch onto the sensor.
after about a minute the gauge hasn't moved.

What am I missing?

Was the case if the sender grounded when you heated it? If not you will not see the gauge move. They measure resistance to ground.

Yup - ground the body of the sensor, plug in the wire to the gauge and then heat it up. if you can, put it in boiling water and you'll find out where 212 is on the gauge.

I bet I didn't have it grounded when I tried it. 'll try it again

yeah with the ground hooked up the gauge moves.

Any chance the taco plate isn't getting a good ground?

Maybe run a wire form under one of the small bolts to a good ground?

are you using a sealant on the sender threads? May interfere with a good ground.

Not sure if the engine builder used sealant on the small bolts or not.

I'll clean it up and try to make sure I get a good ground