Just for note- 91 uses a switch... Noted "Closed with normal oil pressure"... I wonder what kind of magic it would take to convert it... Maybe an 88 gauge & sender? Wiring is near the same...

Scott

 

You would just have to bypass the resister, install an oil sender extension and a oil sender.

You can get the oil sender extension from any salvage yard that has a 88 or older F-series truck. You use the sender from the same truck or buy and new one.



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Put the real sender on the engine. Pull IC. Solder jumper wire across resistor on IC circuit board. Put IC back in and you have a real (electric) gauge that will fluctuate with engine rpm / temp. Down side is it will fluctuate with voltage changes.
That's what I did on 1989 super duty.

 

So you're saying the gauge itself simply needs modification, not replacement, and the switch is replaced with an extension & sender? Cool- That sounds easy enough! As to the voltage changes, a voltage stabilizer circuit can be added to relieve that problem... A simple Zener Diode in the right place...
(Thanks to Subford as well as WTroger)

Scott

 

All the info on the fake/real oil pressure gauge is well documented, but the real reason this silly modification ever saw the light of day is that people assumed their engines were worn out because of low idle oil pressure readings.

I would rely more on oil consumption and compression leakdown to determine if my engine needed rebuilding. Low oil pressure alone, especially at idle does not indicate a severely worn engine.

I would specifically never replace the bearings without turning the crank. Low oil pressure does indicate possible wear, but there is not a problem till it's knocking and higher pressure only indicates increased restriction to oil flow.

Another myth.

This is a problem that really does not happen. The factory gauge configuration has regulated voltage applied to the gauge movements. Gauges operate on current. Sure, voltage fluctuation can affect current as per Ohm's Law, but it is already considered in the gauge package design. No need to reinvent the wheel, (or regulator).

 

Figures probably the only recall or TSB that the PO ever did. LOL
Trav

 

Right. The biggest problem is finding a quality sender to put on there. I am on my 3rd one in the 4 years I've owned this truck. Need to find a better solution.

I didn't get the factory pipe nipple... just made one out of 1/4" NPT pipe.

Subford! That better not be your motor with a FRAM orange can of death on it and grease all over...

 

No that was on a 1988 van I bought with a bad engine. I replaced the engine along with a FL1 oil filter that I keep a lot of in stock.
The photo was taken just before the engine was pulled.

 

Bringing this thread back up, as I am getting ready to do the mod...

Any chance you have a photo of the mod? I am getting ready to do it before I put the engine and trans in (hopefully) this weekend, and have the new sender already in hand...

Any chance of a photo? Or a drawing? Just need to figure it out... Any idea why they gave the sender a 45 deg. angle on the factory extension?

Thanks!
Scott

 

The 45deg I think was for clearance between the sender and the fuel pump.
On a 460 the sender just screws in in place of the oil switch.

You might want to go to the below link for some photos:
Ford Oil Pressure Gauge Fix
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https://www.ford-trucks.com/forums/1270363-oil-pressure-switch-to-sender-conversion.html

http://www.supermotors.net/registry/media/768241

http://www.supermotors.net/registry/media/281470

Just did the mod. It's great having the gauge working.

 

Not only EXCELLENT! but WONDERFUL! as well- THANKS!

All the info I needed- I printed out a good bit of it, and should make a nice, easy job now- Thanks!

Scott

 

Did the mod to the gauge last night- For the first time, I managed to get the cluster out happily... Of course MY mistake was removing the wrong resistor first... Dummy... I removed the lower one for the fuel gauge (510 ohm) instead of the 22 ohm oil pressure one... So I had to put 2 resistors in series in its place- a 330 & a 180... Then I removed the CORRECT one, and gently soldered in a jumper wire... I'll know how it works when i get finished with the engine reinstall...

Not a hard job- except for me screwing up. (To be fair, I did have the cluster rotated 180 on my desk when I was working- I simply rushed a little. And got what I deserved for rushing)

Scott

 

Would this hold true for the diesels as well? My new-to-me '90 with the 7.3 _appears_ to be working as a proper gauge. It slowly works it's way up to about 1/4 of the way over while cranking, then pops to the middle of the gauge when the engine starts...and given that I need to fix the return line leaks, there's a LOT of cranking happening before it fires up,lol.

 

Possibly, but I am not sure of the specs for the diesel... If it has a big **** looking sender, it is probably a real gauge- if it is a small switch, then not... But I am guessing on a diesel...

Scott