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Discussion Starter #1
I have all of my guages working now [see previous post "Wiring Woes.." except for the damn oil pressure guage. I know I have oil pressure - just the factory guage is not reading anything. everything is hooked up correctly, and all terminal plug connections are tight as they should be. I did buy a new oil sending unit. i told them it was for a guage - not a light.

Is there a difference between a light O.S.U and a guage O.S.U. ??? could that be the problem ? I mean visually the new sending unit LOOKS just like my old one, but alas - 'tis does not work... :( and I already threw the old one away :: :( :: :(

any suggestions ?
 

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I am not sure about the type of switch originally installed on your car but, most pressure switches for oil gauges are shaped like a dome. Most of the switches designed to work with idiot lights are the smaller style of switch.

I would double check with your supplier of your current switch to be sure.
 

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Yes, they are different. As already posted, the sender for use with gauges is larger and shaped like a dome.

Another thought... by any chance did you use teflon tape when you installed it? And might you have used so much tape that the sender is not making electrical contact (ground) with the block?
 

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I had problems with a Standard Ignition OPS for a gauge in my '67. Seems the output terminal was too small diameter for the push-on terminal in my wiring harness. I didn't want to crimp my wiring terminal, so I bought a Borg Warner OPS and it fit and worked perfectly.
 

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I had the same problem on the 66 I bought last March. The sender for the gauge is larger in diameter, deeper and as indicated in a previous response, the top is dome shaped. Also there is an extender that screws into the block. The sender then screws into the outboard end of the extender. I found that the sender for a light fits directly onto the engine between the fuel pump and the oil filter without the extender. The gauge sender does not fit in that location and has to be fitted at the end of the extender. Mustang Depot sells a chrome extender that I was very pleased with.
 

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Test the system by grounding the wire to the sending unit. The gauge should go to the far end of the scale. If not, the sending unit is not the problem.
 

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Discussion Starter #7
Another thought... by any chance did you use teflon tape when you installed it? And might you have used so much tape that the sender is not making electrical contact (ground) with the block?
hmm.... yes I did use teflon on both the extension and the sending unit.. I would have thought that threading it in wouild have cut the teflon to make contact - but that is a great idea to check. thanks bud!
 
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