I have a 93 f-150 w/ a 5.0. My oil pressure would fluctuate rapidly from none to normal. I figured that could not actually be happening so i replaced the sending unit. Now the oil pressure reads normal, but in the exact same location all of teh time. I thought I had read that this truck had a "off or on" type sending unit/guage which read out on the dash as normal or no oil pressure, although I do believe that before I replaced the sending unit it did fluctuate correctly with rpm. Is there a different sending unit I can put on to make it actually read the pressure, and if not what can I do to get the real reading.

thanks,
travis

 

Why not buy a mechanical gauge that you can test it with
OR
Tee in a mechanical gauge that rests/mounts on the inner fender
to check periodically.
I don't care for mechnical that brings oil line into the cab,just in case the lines bursts.
That way you have both your factory gauge and a underhood gauge for verifying pressure.


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[updated:LAST EDITED ON 18-Jul-02 AT 08:30 AM (EST)]You can change your sending unit to a variable type, but you will need to pull your instrument cluster and jumper the 20 ohm resistor.(ask for a sending unit for a 92 mustang gt). Actually, Ford has used the same sending unit for as long as I can remember. My 68 Mustang had the same one. So almost any analog sending unit from a Ford will work. Remember, your gauge may not be calibrated, but you can get a relative indication of changing pressure.

The direct reading gauge is more reliable. I did both on my Explorer, leaving the real gauge under the hood for confidence checks periodically, and having the electric one work so I could tell if I lost pressure at hot idle (traffic lights, etc).

Winford

 

I purchased the "real" sending unit from Ford for $30. Installation is a bit of a problem on a 302 in an F-150. the location on the engine block is too close to the oil filter for a direct replacement, as the sending unit is much larger than the original pressure switch. A pipe nipple and elbow are requred. There is very little clearance to the frame crossmember. Make sure that the sender can't hit the crossmember as the engine mounts flex. A broken pipe nipple or sender would cause a severe oil leak.

Jim

 

I was just working on doing this mod this morning. I got it all hooked up and it works like it should, but the new sender is up against the oil filter too close. I'm thinking I just need to extend it farther out. Any ideas here?

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[font color="green"]1995 F-150 Supercab XLT 4x4 302 M5OD 8' bed [/font]31x10.50's
[font color="green"]1986 F-150 4x4 300 I6 NP435 [/font]Warn hubs, DeeZee bed caps, '96 XLT bench seat, new paint job

 

Does the sending unit screw directly into the block, or does it have a hexagonal male/female/45degree adapter? If it doesn't have that adapter, that's what you need. There was one on my explorer. I have not yet done my f150, as I have the direct reading gauge on the dash panel. Those adapters are available from Mustang parts houses, for about $10. You can also use standard plumbing, although it doesn't look as neat. And I would use brass if possible. Just personal preference.


Winford

 

My switch origninally screwed directly in. I used a 2" brass piece plus a 1" coupler and it was still too tight. Is that 45 degree adapter stock on Mustangs? (Don't some of them have a "real" oil pressure guage?)

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[font color="green"]1995 F-150 Supercab XLT 4x4 302 M5OD 8' bed [/font]31x10.50's
[font color="green"]1986 F-150 4x4 300 I6 NP435 [/font]Warn hubs, DeeZee bed caps, '96 XLT bench seat, new paint job

 

So if I understand correctly, I can get this new sending unit from ford and that will read the actual pressure, or get one from another vehicle as mentioned and just jump the resistor? If i get the one from the ford dealer does the resistor still have to be bypassed?

 

Yes, I the resistor will have to be bypassed in any case, because the switching type sending unit sends a full signal to the gauge, which moves approximately half scale. So if you don't jumper the resistor, you will get very low readings all the time.

And all (up to 93) Mustang GT's had the real analog type sending unit, and the adapter was standard equipment.

Standard plumbing works ok, but I would be wary of having too long a piece of pipe extending from the side of the block. Never heard of it happening, but I can imagine the normal engine movements and vibration causing stress cracks in it if it is too long.



Winford

 

My truck runs rich and when I'm stopped the battery gauge goes down and my pressure gauge goes to nothing. When I give it gas it goes back up, maybe it could be improper current going to the sending unit?

 

ok fellas i really want a simple question answered i have an 86 150 with a 302 and is efi and has had oil press probs b4 but that is besides the point right now i changed my oil press send unit b4 and this is a metal canister type item that screws into what may be a hexagon shaped rod coming from the block and this sending unit sits behind the power string pump bracket my questions are is mine the accurate 1 or is this the on/off 1?? and also how would something that only in a sense reads on and off be accurate enough to show changes in pressure ???

i am no x-pert but i would think in the case of the on/off style the slightest change wouldnt be noted or would cause some sort of a vehicle shut down because the slight change in pressure could bring the reading to 0 and trip something in the computer as a preventative measure to protect engine uit would shut it down

 

>ok fellas i really want a simple question answered i have
>an 86 150 with a 302 and is efi and has had oil press
>probs b4 but that is besides the point right now i changed
> my oil press send unit b4 and this is a metal canister
>type item that screws into what may be a hexagon shaped
>rod coming from the block and this sending unit sits behind
>the power string pump bracket my questions are is mine
>the accurate 1 or is this the on/off 1?? and also how
>would something that only in a sense reads on and off be
>accurate enough to show changes in pressure ???
>
>i am no x-pert but i would think in the case of the on/off
>style the slightest change wouldnt be noted or would cause
>some sort of a vehicle shut down because the slight change
>in pressure could bring the reading to 0 and trip
>something in the computer as a preventative measure to
>protect engine uit would shut it down

You've got the good one. Read on below.

1.) The on/off switch is about the size of peppermint with a blade lug on top and screw threads on the bottom. This sensor switches (via a small piece of metal that flexes) at about 4 to 7 psi of pressure. Combined with the 20 oHm resistor inline, the gauge on YOUR dash will show either NO PRESSURE or approx. 1/2 way UP THE GAUGE. It's a lousy way to run a railroad but you'll find that in MOST cars with idiot lights and idiot gauges. (Don't you just love engineers that have NEVER gotten under the hood of a vehicle before!)


2.) The gauge sensor/sending unit (ANALOG) is the LARGE BELL SHAPED unit. It has a metal tube coil that expands and contracts with changes in pressure. this metal tube coil has a small wiper that contacts a variable resistor (kinda like you're gas sender/gauge....only this works better!) which will end up showing on your gauge.
YOU MUST BYPASS THE 20 oHm RESISTOR IN ALL CASES OF USING THIS TYPE OF SENSOR whether you pay $20+ at the dealer or $6 at Western Auto/Pep Boys/Autozone/etc.....it's the same sensor.

If you think that paying the dealer will help with guilt trips......pay the dealer. Otherwise save yer $$$$$ and get the sending unit at the local parts store.

Larry

 

well larry i thank you for youre helpful input on the subject and i am srry that was so long but i was really tired last night and just kinda rambling on and on to the public via the keys under my fingers