Just been trying to test the temp gauge to actual temp, i thought if i remove temp sender pop it into boiling water, switch ignition on , then see what the gauge reads.
But oh no, its not that simple, all other gauges come to life, except the temp gauge.
Does anyone have a remedy, so that i dont have to bung up the hole in the head , fill up with water, and start the engine running.

could it be lack of an earth from the engine?

you probably need to earth the body of the sender to complete the circuit

I would think the temp gauge would need earhed. ( that how the work out the temp ).

So as you were doing --- but a bit of wire from the treads back to the engine.

regards

Agriv8

Cheer's fella's.Brad.

It worked a treat.
When you look at my temp gauge you have the 90deg in the center(its a smiths gauge) then small gap then a mark(guessing this is 100deg) then slightly bigger gap to 140deg, my problem is, when sender was placed in boiling water it was between 100 and 140deg, even though it is a Smiths sender unit.
What can i do to fix this missreading, thank's Brad.

Did you also have a thermometer to check the temp (as any contaminant in the water could affect the boiling point) and is it possible that the sensor was touching the sides of the container?
If when you earthed the sensor the wire could possibly conduct additional heat.

[Edited on 24/1/07 by Schrodinger]

I used fresh water in a kettle, and no sensor was not touching the sides.
I have suspected for a while now that the temp reading was out.

Yes I have a temp probe for my multimeter.

regards

Agriv8

how did you power the temp sensor - some need a stabiliser so only get 9v normally, if you gave it 12 it might over read.

The senor was fed by the car loom, and the gauge is definately 12v.

Suspect it could be 10% out of true...most guages are used just to notice if anything out the norm is happening, ie running hotter than normal. I would not be too bothered about it being spot on accurate, just use it as a reference to the normal running temp.
If it really bugs you you could use a variable resistor to drop it to the correct reading, bet then it is incorrect somewhere else in the scale.

Or else stick a pin in the dial at 100 and the needle wont go too far then .

quote:

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stick a pin in the dial at 100 and the needle wont go too far then .

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Didn't Smiths use colour coded senders for thier temperature gauges? the colour of the plastic insulation around the connection could be a clue. Speedy cables are probably the best people to speak to?