Rebuilding/repairing oil pressure *light* switch question

[jawn101]

While my muffler was off a few weeks ago, I knocked the connector for this off. No big deal. I decided to spin the spade a bit to reduce the risk of the wire touching the cat. After I put the car back together, I realized that the oil light no longer came on with the key in the 'ON' position (with the battery light)

Just today I decided to dismantle my old pressure light switch to see how it works, since I remember David T saying that these were rebuildable. And it clearly is - it's a very simple normally closed spring switch inside. When oil pressure is applied from the inside to the plunger, it opens the circuit. I measured the ohms across the installed switch and my spare and realized that the switch was open even at rest. So I tightened the nut on the outside of the post some and voila - the light works at key-on again.

Went for a drive and realized that the light is also on pretty much all the time now.

Is there a way to know if it's "calibrated" properly? I could try setting it like cracking the injectors on the FD - back the nut off until the light goes out then turn it very slightly until it comes on? Or are there electrical measurements I could take to set it?

Also, I'm having a hard time visualizing this for some reason. How will turning the nut clockwise affect the switch, vs counter clockwise?

[David T]

The calibration is totally dependent on the pressure of the spring. If the light is on all the time you didn't reassemble it correctly and it is grounding itself. Pull the switch out and see what is touching. It is also possible the wire going to the switch is all burned up and the copper is touching bare metal. Put a firesleeve over it or get a short piece of heat resistant wire. That wire gets all crispy from the heat.
David Teitelbaum

[jawn101]

I should clarify. I didn't take apart the one that's in the car, just turned the center post nut a bit after I realized I had messed it up by turning the tab. Wire is fine and not grounding. Under heavy engine load (rapid acceleration on the highway) when the oil pressure climbs higher, the light goes off. The problem is entirely within the switch and I'm just curious if I'm on the right track with my proposed solution to try and get it reading correctly again.