Oil pressure sender
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Senior User
Joined: Mar 2003
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From: Wisconsin
Oil pressure sender
My oil pressure sender is going on my '92 bronco 302. I was going to change it out tonight, but there is no way I could get a wrench on it and my sockets didn't match the end on the sender right. Is there any special tool or trick to get this thing out? Thanks in advance for any help.
Post Fiend
Joined: Nov 2002
Posts: 9,987
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From: Memphis, TN
That's actually not a "sender" - just a switch that turns on at ~6psi. 
You can retrofit an older (pre-'87) sender and short across the 20 Ohm resistor on the back of your instrument cluster to make the gauge actually work.
Why do you think the switch is bad? Have you checked your oil pressure with a real mechanical gauge? You can get one cheap at Wal-Mart or any parts store for under $15 and use it temporarily just dangling under the hood.
Until you know what the oil pressure really is, I wouldn't change any parts. When you do decide to remove that thing, you'll probably have to use an open-end wrench and work from under the front of the engine. That's what I had to do last year on my brother-in-law's truck when his pressure dropped. Unfortunately, he needed an engine.
You can retrofit an older (pre-'87) sender and short across the 20 Ohm resistor on the back of your instrument cluster to make the gauge actually work.Why do you think the switch is bad? Have you checked your oil pressure with a real mechanical gauge? You can get one cheap at Wal-Mart or any parts store for under $15 and use it temporarily just dangling under the hood.
Until you know what the oil pressure really is, I wouldn't change any parts. When you do decide to remove that thing, you'll probably have to use an open-end wrench and work from under the front of the engine. That's what I had to do last year on my brother-in-law's truck when his pressure dropped. Unfortunately, he needed an engine.
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Senior User
Joined: Mar 2003
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From: Wisconsin
I know the switch is bad because the last couple of days when it got to almost freezing, the oil pressure gauge didn't register anything until the engine warmed up a bit. The days when its cold, the gauge will go through its normal sweep when I start it up and then just go back to way past the L mark like when the truck is off. So when ever its warmer outside, the gauge displays normal pressure.
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Joined: Oct 2003
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So, steve83, what you said was that this "oil pressure sender" is basically an on and off switch? That it only works or shows pressure on the gauge when the "sender"sees 6psi? If that was the case then how does the gauge in the dash now what degree of pressure or amount of pressure to display? If it was an on and off switch I would think the gauge would just display high(6psi) or off, nothing else. Am I right or wrong in assuming this? Where is the sending unit located that sends a signal or voltage to the dash gauge that woud tell the dash gauge what to display? Just wondering cause I might need to replace the same thing?
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
G-Force
You didn't say what kind of truck you have, but yes: the switch is either on or off. It sends current to the gauge through the resistor, which puts the needle in the NORMAL range. It never shows the oil pressure, or anything resembling the oil pressure. It only tells you if you have more than 6psi. Ford just used a gauge face to make people THINK their engines had good pressure.
The truly variable "sender" is at the parts store, listed for pre-'87 F-series & Broncos and costs under $15. It fits the same hole as the switch, but it's much larger, so Ford used an extension tube on V-8s to push it out from the block where there's enough room. You can use standard plumbing fittings and teflon tape instead of trying to find an original spacer.
You didn't say what kind of truck you have, but yes: the switch is either on or off. It sends current to the gauge through the resistor, which puts the needle in the NORMAL range. It never shows the oil pressure, or anything resembling the oil pressure. It only tells you if you have more than 6psi. Ford just used a gauge face to make people THINK their engines had good pressure.
The truly variable "sender" is at the parts store, listed for pre-'87 F-series & Broncos and costs under $15. It fits the same hole as the switch, but it's much larger, so Ford used an extension tube on V-8s to push it out from the block where there's enough room. You can use standard plumbing fittings and teflon tape instead of trying to find an original spacer.
