Oil Pressure/Water Temp Sending Units and Idiot Lights ???

[NealinCA]

I hope this isn't too off topic.

Unfortunately I am not working on a hot rod, I am working on a tractor, but I think the topic is still related.

I have two "idiot" (warning) lights that are supposed to be hooked to sending units for oil pressure and temp. Both sending units are broken and need to be replaced.

I tried to get replacements from the tractor parts place, but they are special order and would take 1-2 weeks. I need to get this tractor out of the middle of my shop, so I can get back on the 32 p/u project.

Is there a generic sending unit that will work? What is the theory here? Are they just a switch that opens or closes at a certain pressure or temp?

The oil pressure sending unit is 1/8" NPT and the temp unit is M16x1.5 if that makes any difference.

Any input would be appreciated.

Thanks,

Neal

[roadstar]

Sending units that turn on lites are different than one used to read on a guage.
most idiot lite sender are just a ground switch. Any one with the same treads should work. The oil press sender needs presure to turn it off, so it will come on when you loose oil presure. and the temp will come on at a determined temp usually about 230. Both are basicly the ground side of the lite.
A good parts store guy( not Murrys or Auto Zone) should be able to look up something that will work.

[NealinCA]

Thank you. That makes sense.

I have always used gauges, but I figured that the warning lights must just be a simple switch.

Off to the real parts store...

Neal