Oil pressure bypass switch

[AquaHydroChem]

In the pix you can see a throttle box
There is some kind of switch attached to it that is broken could be an oil pressure bypass switch, over ride switch or a momentary switch, not exactly sure what its purpose is
But I do know it has something to do with the oil senor which is located on top of the oil filter
And when the oil level drop the machine should shut down
Have the Briggs and stration manual and the hydramaster manual but there is nothing in it about this switch or the sensor

 

[AquaHydroChem]

Ok I have just tested it with the multi meter and when it wants to work it is a N/O switch

 

[ericmark]

Could it be stop button?
Seems likely it only one wire.
Normal idea is to earth wire to coil no spark engine stops.
That would also explain why connected to low oil switch also stops engine by shorting out ignition low tension.
What do you think. Long time ago since worked on B$S realised throw away engine when one thing goes faulty engine normally worn out. Ali big ends and bore etc. They run well but once they start to give trouble every thing seems to go together and new ones were so cheap if you did one up it could cost more than new one.

 

[bernardgreen]

It almost certainly is (was) a stop switch.

 

[AquaHydroChem]

So you two think it’s for stopping the engine
If you look at the first picture it looks broken maybe it had 2 wires I don’t know
But if it’s for stopping the engine then it will need to we wired to the engine stop lug
On my oil senor there is one male spade terminal on it and roomer has it that the oil senor is earthed through the body of the engine
If I replace it with a push switch N/O
Wire one terminal of the switch to the oil senor and the other to the engine stop lug will it work or should I wire the senor to the engine stop lug and as well to the push switch using a piggy back connector and the other wire from the switch wire it to earth

 

[ericmark]

From what I can remember you will need piggy back and new switch one wire to frame other to engine stop.
It was a long time ago so may have it wrong.

 

[bernardgreen]

But if it’s for stopping the engine then it will need to we wired to the engine stop lug

Yes but read to the end.....

The oil sensor switch closes when the oils system is faulty. this will short out the ignition and prevent the engine spark plug firing.

Normally the shorting is to the metal framework / cylinder block of the motor. A stop switch does the same thing when pressed so the stop switch must be wired in parallel with the oil switch


BUT if the oil pressure sensor is closed when no oil pressure then the motor can not be started as without oil pressure the ignition is dis-abled by the lack of oil pressure. So the oil pressure sensor must be dis-abled ( taken out of circuit ) to allow the machine to start and until oil pressure has been built up. This could be a start enable switch in series with the oil pressure sensor. When operated it DIS-CONNECTS the oil sensor switch from the engine stop lug.

To acheive this there would as you believe have been two connections to the switch.

 

[AquaHydroChem]

Would ever of theses diagrams do the job

 

[bernardgreen]

Wired as the first one the either the switch or the oil pressure will stop the engine.

Wired as the second one the oil pressure will only stop the machine if the switch contacts are close. This would be necessary to allow the machine to be started before oil pressure built up.


The third one is pointless as the oil sensor is shorted ou with both sides connected to ground.