Oil Pressure Switch

[mack]

Not exactly sure how this works. The flow oil passed the bottom of the tunnel creates a vacum effect that draws the switch down off the contacts so the light goes off?

[Yard Dogg]

I actually disected one cause my idiot neighbor had pulled the wire out of it, I'm just trying to remember how it worked. The wire goes inside into the first layer of plastic, then through a machined tube all the way to the top of the sending unit. Inside that tube along the wire is a diode. This wire provides the electrical contact for a metal type plate at the top of the SU. Around the tube, but still inside the SU, in the wet side of the SU, there is a float thingy that slides up and down the tube. When the float looses contact with the weird plate at the top, it turns the light on. Sorry I can't be of more detail, I'm not an electrician and the device had some strange alien to me materials the likes that I've never seen before. Since it is submerged in oil, it makes sense. My repair attempt was a failure. New ones are only 15 -20 buckaroos though. You can buy one for an XJ1100, xj550 and many other bikes, possibly Viragos'. Hope that helps.

[Yard Dogg]

My previous statement could be wrong. I can't remember if the contacts inside the switch were at the top or bottom like you're suggesting. I do remember for a fact that the wire with the diode ran all the way to the top of the sending unit. The float may just work the way you mentioned cause now I'm remembering a spring? IDK now. I should have taken pictures but I was on a mission. In any regard, the chances of destroying the SU during repair attempts, is greater than the effort to buy another.

[crazy steve]

It's a simple pressure switch. You have a sealed diaphram to keep the working fluid out of the electrical bits and giving something for the pressure to work against and prevent leaks, a spring to hold the contacts open or closed, and the contacts. Apply pressure to overcome the spring and the contacts change state. Nearly all oil light switches are NC contacts with one side grounded to the housing.

If you need a replacement, these are very generic parts. There's two basic things you need to know; 'range' (at what pressure do the contacts change), and getting the right thread so it screws in. Size, shape, and how the wire connects will vary by application. Automotive units typically operate at 5-7 PSI which should be fine for an XS with it's 'plain' bearings. Motors with roller or ball bearings (think Harley) don't produce much pressure (lubrication is by volume) so they typically operate at 1-2 PSI.

Note that these are a on-off switch, not a sending unit. Sending units work similarly, but vary resistance to ground.

[Yard Dogg]

There you go, just buy another.

[mack]

I have

no way of knowing at this stage if it will work or not. I was working on the upper case cleaning it. Getting it ready for the transplant and had removed the sending unit. I took some time to look it over and couldn't quite figure out how it worked. being an old engineer it was intriging to me. I think I have four here, one should work. Thanx for the in put guy's.

[Yard Dogg]

no way of knowing at this stage if it will work or not. I was working on the upper case cleaning it. Getting it ready for the transplant and had removed the sending unit. I took some time to look it over and couldn't quite figure out how it worked. being an old engineer it was intriging to me. I think I have four here, one should work. Thanx for the in put guy's.

If you have one for an XJ, I'll buy one. Mine has a flange with two bolts that run through it though, It doesn't screw in as I am led to believe the XS's have.

[TopCatGr58]

Hey Dogg,

You're mixing apples and oranges when talking about the XS vs. the XJ's devices. The XS IS as Steve stated, a simple pressure switch. The XJ's is an oil LEVEL sensor, not a pressure sensor...it has a float in it that rises and falls with the oil level to alert you when the oil is too low, but it does NOT tell you whether you have oil pressure!

Mack, you should be able to put an ohmmeter/continuity testing device on any of the XS units, one on the wire end, the other on the threaded end.

It should show continuity...or zero ohms, then push a screwdriver/pencil or such into the opening to press on the spring to separate the contacts and the continuity should stop/read open circuit.

T.C.

[mack]

Dog

Mine are all XS's
Cool TC, thanx.