Oil pressure gauge
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Freshman User
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Oil pressure gauge
After noticing that my oil pressure was rock solid and never varied with rpm (even when the engine was hot), I did some research on the net and found an article discussing the this.
It seems Ford replaced the analogue sending unit (~1985 thru early/mid 90s) with an on/off switch that triggers around 4 or 5 psi and used a 20 ohm resistor in the electrical path to fool the gauge into reading in the normal range if there is "any oil pressure". They implied the did this to keep consumers from worrying about the fact that true oil pressure readings varied a lot with rpm.
A mod was shown to return the gauge to its analogue reading. This consists of swapping the oil pressure sensor for a true analog sensor (from a 1984 F150) and bypassing the 20 ohm resistor. Accordingly, the gauge would then show a more representative analog reading proportional to oil pressure.
Has anyone tried this? Exactly where is the oil sending unit on a 2.9 V6? And on a '90 Bronco II, is the 20 ohm resistor wired "inline" near the oil pressure sending unit or is it on the back of the instrument panel?
'90 Bronco II XLT
'99 Firehawk #521
It seems Ford replaced the analogue sending unit (~1985 thru early/mid 90s) with an on/off switch that triggers around 4 or 5 psi and used a 20 ohm resistor in the electrical path to fool the gauge into reading in the normal range if there is "any oil pressure". They implied the did this to keep consumers from worrying about the fact that true oil pressure readings varied a lot with rpm.
A mod was shown to return the gauge to its analogue reading. This consists of swapping the oil pressure sensor for a true analog sensor (from a 1984 F150) and bypassing the 20 ohm resistor. Accordingly, the gauge would then show a more representative analog reading proportional to oil pressure.
Has anyone tried this? Exactly where is the oil sending unit on a 2.9 V6? And on a '90 Bronco II, is the 20 ohm resistor wired "inline" near the oil pressure sending unit or is it on the back of the instrument panel?
'90 Bronco II XLT
'99 Firehawk #521
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Joined: May 2000
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Oil pressure gauge
I've never tried that or heard of it. But if you are truely consered with your only pressure(as you should be) you should do what I am fixing to do. Go with a mechanical guage. They are by far more relable.
Senior User
Joined: May 2000
Posts: 101
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Oil pressure gauge
If its in the same place as my 2.8, it's towards the front of the engine infront of the motor mount. I just got mine installed tonight and it confermed what I thought. The stock oil gauge sucks.
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Freshman User
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Oil pressure gauge
gimps,
When you say rock bottom, are you saying you get no reading at all? Zero, nada? If that is the case it would appear that either your sending unit is bad or disconnected, or perhaps a fuse is blown.
In my case, my oil pressure reads on the "O" in NORMAL anytime the engine is running. It never varies with engine temp or rpm. Never. In essence the oil pressure gauge has been spoofed by the use of an on/off switch plus 20 ohm resistor in place of a true analog pressure sensing sending unit. Ford did this sometime in the mid '80s and continued the practice for about 10 years or so. Their rationale at the time seems to have been a desire to cut down on customer complaints about oil pressure variations. So they fixed it so it never appeared to vary!
Imagine if they had "fixed" the speedometer that way. It'd always read either zero - or 55 mph. Nothing in between or above. "But officer, I can only drive at 55!"
IMHO, this was NOT one of Ford's "Better Ideas!"
'90 Bronco II XLT
'99 Firehawk #521
When you say rock bottom, are you saying you get no reading at all? Zero, nada? If that is the case it would appear that either your sending unit is bad or disconnected, or perhaps a fuse is blown.
In my case, my oil pressure reads on the "O" in NORMAL anytime the engine is running. It never varies with engine temp or rpm. Never. In essence the oil pressure gauge has been spoofed by the use of an on/off switch plus 20 ohm resistor in place of a true analog pressure sensing sending unit. Ford did this sometime in the mid '80s and continued the practice for about 10 years or so. Their rationale at the time seems to have been a desire to cut down on customer complaints about oil pressure variations. So they fixed it so it never appeared to vary!
Imagine if they had "fixed" the speedometer that way. It'd always read either zero - or 55 mph. Nothing in between or above. "But officer, I can only drive at 55!"
IMHO, this was NOT one of Ford's "Better Ideas!"
'90 Bronco II XLT
'99 Firehawk #521
