mibars
Full Access Member
- Joined
- May 13, 2023
- Posts
- 268
- Reaction score
- 442
- Location
- Nadarzyn, Poland
- First Name
- Michal
- Truck Year
- 1990
- Truck Model
- Suburban V1500
- Engine Size
- 350 TBI
Hi,
Ever since I've replaced my oil pressure sending unit I get low oil pressure readings, about 15 PSI most of the time.
I'm using Standard Motors PS-262 sensor.
When cold or at high RPM it may show about 20 maybe 25 PSI, when hot and idling even close to 10 PSI, definitely below 15 PSI mark. So I was worried about engine condition.
I removed it and pressure tested and I have some interesting findings.
My setup uses air compressor, oil sending unit cross threaded into air gun with some help from teflon tape to keep it sealed. Ohm-meter on a middle prong, grounded to sender casing. I did couple of readings showing inconsistent values, settled on doing one reading while increasing pressure, 2nd one while slowly releasing air. My multimeter is showing about 0.6 ohm when shorted, about 0.7 ohm conencted to sending unit at 0 PSI.
Here are my results in a chart:
Blue is the reading I've recorded while I was gradually increasing pressure. Red is when I was slowly releasing it. I went to 6 BAR (87 PSI) which is above what the stock gauge shows (60 PSI).
Couple of observations:
-Clearly a difference when pressure goes up VS when it drops (corresponds with observations from driving)
-Not too linear
-Resistance change is not smooth, there are noticeable steps which I could see when pressure was slowly changing
-Low pressure accuracy is poor, 1 BAR (14.5 PSI) may read 6.1 or 16.6 ohm.
-sensor doesn't seem to go to 90 ohm at 60 PSI (4.1 BAR), but more like about 90 PSI
-Just above 0 PSI there is like intermittent dead spot that reads infinity. I didn't see it every time.
My big question is: My gauge is 0-60 PSI, sensor seems to go all the way to 90 PSI. Is this pressure sensor wrong for application?
If so: Is there a way to correct the reading e.g. by adding some resistors to the gauges?
I know that some square bodies came with 0-90 PSI gauges.
(edit: typo correction Ohm --> PSI on a graph and chart)
Ever since I've replaced my oil pressure sending unit I get low oil pressure readings, about 15 PSI most of the time.
I'm using Standard Motors PS-262 sensor.
When cold or at high RPM it may show about 20 maybe 25 PSI, when hot and idling even close to 10 PSI, definitely below 15 PSI mark. So I was worried about engine condition.
I removed it and pressure tested and I have some interesting findings.
My setup uses air compressor, oil sending unit cross threaded into air gun with some help from teflon tape to keep it sealed. Ohm-meter on a middle prong, grounded to sender casing. I did couple of readings showing inconsistent values, settled on doing one reading while increasing pressure, 2nd one while slowly releasing air. My multimeter is showing about 0.6 ohm when shorted, about 0.7 ohm conencted to sending unit at 0 PSI.
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Here are my results in a chart:
You must be registered for see images attach
Blue is the reading I've recorded while I was gradually increasing pressure. Red is when I was slowly releasing it. I went to 6 BAR (87 PSI) which is above what the stock gauge shows (60 PSI).
Couple of observations:
-Clearly a difference when pressure goes up VS when it drops (corresponds with observations from driving)
-Not too linear
-Resistance change is not smooth, there are noticeable steps which I could see when pressure was slowly changing
-Low pressure accuracy is poor, 1 BAR (14.5 PSI) may read 6.1 or 16.6 ohm.
-sensor doesn't seem to go to 90 ohm at 60 PSI (4.1 BAR), but more like about 90 PSI
-Just above 0 PSI there is like intermittent dead spot that reads infinity. I didn't see it every time.
My big question is: My gauge is 0-60 PSI, sensor seems to go all the way to 90 PSI. Is this pressure sensor wrong for application?
If so: Is there a way to correct the reading e.g. by adding some resistors to the gauges?
I know that some square bodies came with 0-90 PSI gauges.
(edit: typo correction Ohm --> PSI on a graph and chart)
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