0-100psi stock oil pressure guage sending unit?

[73k5blazer]

So I have this gauge cluster I built from various pieces:

I used a 0-100psi electric oil pressure gauge. Apparently, that is very not normal. Since I used a standard sending unit from mid 80's truck, that sending unit is probably for a 0-60psi gauge, which seems to be far more common.
Trouble is, I can't find a sending unit for a 100psi gauge. Med. duty parts seem to be alot harder to find, tech's at dealers don't want to waste their time on an oddball lookup.
The way it's installed I have anywhere from 50-100psi pressure showing while the engine is running. I don't believe that's right. I supposed I could swap the gauge itself for a 0-60psi one. But I'd rather find the right sending unit if I could.

I don't remember exactly where I got the gauge. I believe it was the same leftover cab from some med. duty truck I pulled the Tach/Fuel gauge and the air gauge from (btw, that air gauge is nice, stock GM, and it has dual different colored needles with dual air inputs so you can monitor regulated and unregulated OBA). It was late in the yard one day,getting dark, as I was walking back with another part in my hand, I notice this med. duty cab laying on it's side, not on a frame or anything and I happen to notice the cluster, saw it had a tach/fuel I was looking for and pulled it. Best part was he sold it to me for $30. Those tach/fuel gauges with a working printed circuit on the back of the cluster go for $200-300.

Anyway, does anyone know a year and model of vehicle that this 0-100psi electric oil pressure gauge would have come from?

 

[KansasTwister]

Paging fordum.

Could you use some type of tester to see what the range of the gauge is and find a sender to match?

 

[Fordum]

Well, I assume that its a standard variable resistor type. It changes resistance to ground according to pressure.
Somewhere in the back of my mind, I want to say that most GM pressure sensors have the same resistance range.
It just takes more or less pressure to move from one to the other end.

And somewhere I also seem to remember it ranges from 0 to 90 or 100 ohms.
The easiest way to figure it out, is to hang a variable resistor, also known as a potentiometer, from the gauge wire to ground, and move the knob back and forth watching the gauge.
Measure the resistance when its at 0 and when its full scale, and that will give you the readings you need.

The problem comes in when you start trying to find an actual sensor to match those readings.
I don't have a reference for GM part numbers vs ohms or pressure.

However, if the resistance is linear, then you might be able to add a resistor either in series or parallel to shift the readings to the correct range.

This outfit sells a 0-100 psi pressure sender, but I don't know if its the right one for your setup.

https://www.classicinstruments.com/

Bear in mind, that precision suffers when you have more range than you need.

 

[sweetk30]

6.2 equiped truck got 80 . mabye 100 is med duty .

 

[British Slave]

Is the sender different, or is the gauge's span the difference? I would bet the gauge is the difference. I would bet too that the standard sender will work.
I bet 30# on a 0-60 requires the same resistance that 50# does on a 0-100 gauge.

 

[sweetk30]

been told its both each gets its own sender.

 

[British Slave]

I've searched parts listings and can find no 0-100 specific sending unit. Plenty of after market gauges, but no GM.
I still bet it's the gauge face.

 

[ion]

Just get an aftermarket 0-100psi sensor, on the regular 60 psi gauges the sensor is rated for 60 Pei before it will pop. Never assume it will work. You need a 100 psi sensor

 

[British Slave]

GM gauges are 0-90 ohm. And 0-90 ohm is 0-90 ohm no matter what the gauge face says. O ohms means the gauge will read zero. 90 ohms means the gauge will read full deflection, makes no difference what numbers are printed on the gauge face.

 

[73k5blazer]

Yeah, what I find in parts books are listing for sending units "60psi" "80psi" etc and those sending units are different part numbers. ..I don't see a 100.
If I'm really pushing 100psi, I think I'd be blowing out seals. Perhaps I'll just get a 0-60 gauge. These gauges aren't the most accurate anyway, they are more a 'ok, this is where it usally is' and if it's off from that than there's an issue.

 

[80' 427]

I wonder if it is from a C60, they could have had a detroit diesel and they may run higher pressure. I have seen that gauge before and I keep thinking it was in a medium truck.

 

[ion]

GM gauges are 0-90 ohm. And 0-90 ohm is 0-90 ohm no matter what the gauge face says. O ohms means the gauge will read zero. 90 ohms means the gauge will read full deflection, makes no difference what numbers are printed on the gauge face.

Hey bud, 0-90 Ohm only pertains to the fuel tank sending unit level.

 

[British Slave]

Hey bud, 0-90 Ohm only pertains to the fuel tank sending unit level.

Yeah? Someone better tell GM.