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Author Topic: Oil Pressure gauge in a MN12  (Read 1923 times)

J dot Miller

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Oil Pressure gauge in a MN12
« on: November 26, 2007, 08:03:53 PM »
As many of you know or may not know the oil pressure gauge in your Ford is a switch.  The stock oil sender is just a switch not a gauge.  It tells you when the oil pressure if below a certain point.  Nothing else...

A few years back there was an article on "How to convert your oil pressure gauge".  Here are the instructions:

by Mike Maroschak 2001
 [email protected]

      1.Remove sender unit's wire.

      2.Remove oil pressure sender unit with a 1 1/16" socket or the special oil pressure sender socket
        (which actually works better if you have one).

      3.You might have to move some of the accessory belts out of your way.

      4.Put Teflon tape on the new sender unit's threads.

      5.You may have to use a 7/8" open ended wrench to :censor: the threaded pipe (that comes out of
        engine block) slightly one way or the other.

      6.Thread in the new sender as tightly as you can with your bare hands (as you would your oil filter).
        It's easier if you make sure the sender and your hands are dry and grease free.

      7.Re-connect sender unit's wire

      8.A small number of Thunderbirds have the 20 ohm resistor located on the oil sender wire
        approximately 5 inches form the sender itself. If this is the case, bypass or remove this resistor
        and skip steps 8 through 14 (inclusive).

      9.Remove trim around instrument cluster. There are 2 screws at the top, then ease it on out.

     10.Remove screws around instrument cluster. Ease it out several inches, tilt the bottom out, and
        gently pull the 2 connectors off.

     11.Be careful not to scratch the instrument cluster's bezel.

     12.Flip it up side down and solder a piece of 18 gauge (insulated) wire in parallel to the 20 ohm
        resistor behind the oil pressure gauge. There is no need to remove the resistor. Be careful not to
        melt the plastic.

     13.This would be a good time to remove the bezel and clean it.

     14.Also a good time to replace any burnt out bulbs.

     15.Replace instrument cluster.

     16.Start 'er up & check it out!

     17.Remember to check for leaks.

     18.When cold: between M and top line When hot at speed: M When hot in gear idle: between N and
        O When hot in park: O

     19.The oil sender part numbers are as follows:
        Standard Motor Products: PS-60
        Echlin: OP6091
        Motorcraft: SW-1547-B, E4ZZ-9278-A
        AutoZone :  NIEHOFF OP24761

As illustrated in number 18 you will not know what the real oil pressure is.  A colleague asked me how can you read the pressure...  Lets discuss that topic...

The pressure is important if you are racing and can look at both your RPM and your oil pressure at the same time.  That is if you know what pressure you need?  If you can not watch them both and let off the gas when the numbers are not correct a quality gauge is a waste...

The fact is you need around 10 PSI of oil for every thousand RPM's.  Too much pressure will rob horsepower and less pressure will cause internal damage.  Each type of engine is different so you may need more or less pressure.  In general, if you are at 4,000 RPM your oil pressure should be at least 40 PSI.

If you have an after-market gauge how do you know that the gauge is really accurate?  Is it adjustable?  If it is adjustable it can be calibrated.  Is it calibrated against a National Standard?  I have dealt with gauges for many years and I know about accuracy issues.  Wether you buy an after-market gauge or make a calibrated stick on oil pressure gauge for your instrument cluster it will loose accuracy over time.

With most people the money is short and their free time is free...   So buying an after-market oil pressure gauge may not be an option.  O0  Needless to say this is not a hard thing to do.  All you need to do is to have a custom sticker made up??  I would tape (masking) a piece of paper behind the needle and carefully mark up the pressure settings.  There are several ways you can do this:

1.  Use another gauge and compare.  Ge the zero set point and an known number and wing it.
2.  Use a NIST calibrated pressure gauge calibration tool.  They have hand pumps and should be included with a current NIST calibrated gauge. 

Of course I would assume that someone first checked the calibration range of the pressure transmitter. 

The above picture is of a pressure gauge calibration tool.

So if you were so inclined you can borrow or buy one of the above tools and calibrate the gauge yourself???
The 5.4 swap has been called a bad idea, and considered an underpowered considerable waste of time, since 2007.

Nice to see that most donít think that anymore.
Bondfreak13 07/28/09 09:05 PM