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Author Topic:   Oil Pressure Ignition Cutoff System
Dirt Full Roller

Total posts: 47
posted July 09, 2002 06:04 PM
Has anybody seen a system that cuts off the ignition when the oil pressure gets too low?



Dirt Roller

Total posts: 23
posted July 09, 2002 08:36 PM
yes they do .they are called murphy switches.seen in oilfield equipment.i guess that you could hook up with oil pressure light to ground coil maybe

Dirt Full Roller

Total posts: 47
posted July 09, 2002 10:10 PM
I tried something like that without success. I used the regular oil presure switch to trigger a relay which worked fine when the oil was cold. The pressure was able to build up quickly during cranking to allow power to get to the coil and start the motor. But, when the oil was hot, forget it. The pressure never got high enough to activate the pressure switch. I figured I could use a momentary bypass switch when the oil is hot, but I would like something that is more user friendly that doesn't require any driver intervention.


Dirt Full Roller

Total posts: 70
posted July 10, 2002 12:45 AM
Instead of a cutoff switch, I installed and audible alarm (from radoishack)that can easily be heard over the noise from the car. I hooked up an oil pressure sending unit and a water temp sending unit to the buzzer. The sending units are just standard sensors from the autoparts stores for a vehicle with idiot lights. I also have a bypass switch when starting and a test switch. So now I don't have to worry about checking the gauges (or forgetting to). I came up with this after cooking a motor due to losing the water pump belt. I didn't want to make the same mistake twice.

Dirt Forum Racer

Total posts: 87
posted July 10, 2002 12:48 AM
I'm not sure of everyone's opinion on this one, but I'd rather be or have a driver in control of switching that engine off. Install a oil pressure warning light and let the driver shut the engine down when he sees it. It might help prevent a crash from occuring because if the engine shuts down at an inopportune moment it might put the driver at risk. Just my opinion on the subject. Any thoughts?

Dirt Maniac

Total posts: 111
posted July 10, 2002 01:11 PM
Got to agree with you BayouGent. I've seen the kit in question advertised in a Summit catalog i think, it kills the engine when the pressure drops below about 7 PSI. This pressure is low and it shouldn't cause a problem with the runnig but at the same time if the pressure has got that low then you are alredy looking at a rebuild.

Dirt Full Roller

Total posts: 43
posted July 12, 2002 07:11 AM
I used a normally open oil pressure switch with two connector lugs from Advance auto parts. It is a set off contacts rather than a switch to ground like the one normally found on an idiot light. I spliced the switch into the lead that powers my ignition. To get around the starting problem I ran a wire from the ign lug on the starter solenoid. This was originally used to bypass the ignition resistor at start up on older points ignitions. It works to power the ignition while cranking/starting allowing the oil pressure to build to the switch threshhold.

Dirt Full Roller

Total posts: 47
posted July 12, 2002 05:32 PM
That's seems like a good idea for the starting problem. I thought about something like that. You didn't have any problems with engine dying? It seems to me that as soon as the starter switch is released, the solinoid won't be supplying power to the coil and the motor will die unless the oil pressure comes up real fast for the oil pressure switch to close. I'm thinking of a timer of some sort to allow the oil pressure to come up, then allow the pressure switch to work as normal during operation.

What do you think?


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