Vacuum Lines

[TheRev]

The oil pressure sender is nothing more than a ground switch. Without pressure to open it the light should stay on. When pressure is applied the switch opens and the light goes out.

If the light isn't lighting with the engine not running as you say then the new switch is bad I would say.

Do I have the test light procedure correct. The alligator clip on the positive side of the battery and the pointy probe on the screw on the oil pressure unit?

[BA80]

Do I have the test light procedure correct. The alligator clip on the positive side of the battery and the pointy probe on the screw on the oil pressure unit?

Yes........

[CaptonZap]

Where did you get the switch? It sounds like it is backward.
When there is no pressure, there should be continuity, (the light should light), and when the pressure comes up, the light should go out.
The oil indicator lamp and neutral lamp get system voltage from the brown wire, which is hot when the switch is on. So all the pressure switch does is complete the circuit to ground, turning on the light when there is no pressure.

CZ

[TheRev]

Where did you get the switch? It sounds like it is backward.
When there is no pressure, there should be continuity, (the light should light), and when the pressure comes up, the light should go out.
The oil indicator lamp and neutral lamp get system voltage from the brown wire, which is hot when the switch is on. So all the pressure switch does is complete the circuit to ground, turning on the light when there is no pressure.

CZ

That's correct. My initial problem is that I don't have a working dash at the moment, so I have no oil pressure light. I was using a test light as a make shift oil pressure light. However, my first oil pressure switch would light and stay lit. My second one won't light at all. So I am a little confused.

[CaptonZap]

If you can get some help to holdthe test light, you can run a wire from the body of the switch to battery ground, hold the light probe on the center terminal. and have some one blow compressed air into the hole of the threaded part.
I think it should operate around 3-5 PSI, so it won.t take much to see if it works.
One other thing you might try with the old one is to take a piece of welding or other stiff wire that will fit into the hole in the threaded end, and push hard, and see if you can feel any give.
The last one I had apart had a ball bearing that was spring loaded against the case, making continuity, and when the pressure rose, the ball was pushed off the seat and interrupted the circuit. The ball may be stuck with crud, or congealed oil. ?????
Worth a try, and doesn't cost anything.

CZ

[CaptonZap]

That was why I was curious about where you got the new one. They come in all sorts of operating pressure ranges, and make on rise or break on rise, so you need to get the right one. And even then, you might get a bad one out of the box.
If you can get some help to hold the test light, you can run a wire from the body of the switch to battery ground, hold the light probe on the center terminal. and have some one blow compressed air into the hole of the threaded part.
I think it should operate around 3-5 PSI, so it won.t take much to see if it works.
One other thing you might try with the old one is to take a piece of welding or other stiff wire that will fit into the hole in the threaded end, and push hard, and see if you can feel any give.
The last one I had apart had a ball bearing that was spring loaded against the case, making continuity, and when the pressure rose, the ball was pushed off the seat and interrupted the circuit. The ball may be stuck with crud, or congealed oil. ?????
Worth a try, and doesn't cost anything.

CZ