Oil Pressure Sender

drolston

drolston

Well-known member
I have been through three reproduction 50# oil pressure senders on my '41. One failed, the next one showed 15# with the engine off; a second replacement worked okay for a while, now shows 20# with the engine off. Where can I find an original type oil pressure sender. I would even use and 80# unit, knowing that the calibration is way off, but will show a true zero pressure.
 
Didn't I see that the older Jeep 50 pounders are 6 volt?

Probably the same manufacturer as you have already tried, but thought I'd share what little knowledge I have.
 
Current Jeep senders are 24 volt. I will dig deeper.
Are the Jeep units same type mechanism as King Seely that designed for Ford?
 
A Standard Motor Products PS60 has been on my 59AB in the pickup for 12 years. Verified it with a mechanical gauge.
 
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41ford1 said:
A Standard Motor Products PS60 has been on my 59AB in the pickup for 12 years. Verified it with a mechanical gauge.
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Drolston: It is my understanding that the oil presssure gauge is a voltmeter, the negative (or positive on 12 volt systems) being connected to the ignition side of the ignition switch, not the battery side as I suspect yours is connected. The sender furnishes ground. If you ground the terminal on the sender, the gauge should read full scale with the ignition switch on.
 
A reminder : Ford used the King-Seely method of gauge activation and does not operate on simple changes in voltage.
 
Bill OH said:
Drolston: It is my understanding that the oil presssure gauge is a voltmeter, the negative (or positive on 12 volt systems) being connected to the ignition side of the ignition switch, not the battery side as I suspect yours is connected. The sender furnishes ground. If you ground the terminal on the sender, the gauge should read full scale with the ignition switch on.
Click to expand...

As Tubman noted, gauges that are sensitive to voltage would be erratic, due to fluctuating voltage as the generator/alternator output goes up and down with rpm and load on the system. The King Seely design is really a power meter in which the needle deflection depends on how much heat is generated within the tiny heating coil. The amount of heat generated is controlled by the average current allowed through the gauge by the sender. In King Seely senders the "average" current is controlled by points opening and closing the electrical path to ground. The King Seely sender also has a heater coil that bends a bimetal strip with one of the points. The other side of the points is moved by a diaphragm deflected by oil pressure. As the oil pressure goes up the amount of time the points stay closed goes up, the power consumed goes up, and the needle moves higher.

The reproduction senders do not have points. They control the power consumed by varying the electrical resistance through movement of the diaphragm. The inaccuracy of such senders suggests that it is difficult to get the calibration correct. I am hoping that the PS60 sender is better than the ones sold by many early Ford parts vendors.
 
41ford1 said:
A Standard Motor Products PS60 has been on my 59AB in the pickup for 12 years. Verified it with a mechanical gauge.
Click to expand...

I received the PS-60 as described by you and exactly as pictured by petehoovie. It is a switch, not a variable pressure sender for an analog gauge. At zero pressure it is an open circuit, which would leave the oil pressure gauge at zero. With pressure, the internal switch closes and the gauge comes up to about 25 psi and stays there regardless of rpm or engine temperature. The base is stamped 20-21, which I presume is the pressure the switch is set for.

So, if you are okay with an oil gauge that simply tells you whether oil pressure is above 20 psi, or not, the PS-60 is the ticket. Actually that functionality is better than the sender I have that indicated 20 psi with the engine off, so the PS-60 will stay in there until I find a fully functional sender.
 
Received a NOS 50# oil pressure sender from All Ford Parts. Not cheap, but unlike the modern reproductions, it actually works correctly. When I turn the ignition on but don't start the engine, the needle stays at the left stop. With the engine fired up it goes to about 48 lb indication. Drops to about 45 at idle when warmed up. Perfect!
 
Having installed a few of the replacements, take care to ensure that the orifice of the sending unit matches that which you are replacing; I’ve had to bore out a couple.
 
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