99 4.0 orig oil pressure gauge to "true pressure" gauge

[coopab]

One of the quirks about my "new" 99 Ranger with 4.0 was that the oil pressure gauge needle was on the wrong side of the peg. Today I pulled the dash apart to replace the 6 burned out dash cluster light bulbs. While in there I slid the needle off its shaft and replaced it with the needle resting on the peg. Now when engine is running it's more or less "all over the place", usually very high.

I am going to check the connection at the pressure sending unit, but after reading some old threads on this subject I learned that the OEM gauge is really just an "idiot gauge" so I'd like to know how practical it is to replace it with an oil pressure gauge that actuall registers engine oil pressure.

If I don't discover a bad connection on the existing setup, how do I determine if the problem is the current sending unit or perhaps the dash gauge itself?

coopab

 

[rtg143]

Unplug the sender and see what it reads. Then ground it and see waht that does.

 

[Explorin94]

Basically it is a switch and that is it. If you want a gage then go buy a good gage and that will tell you where your pressure actually is.

 

[alwaysFlOoReD]

Pull the sending unit, put in a tee, put sending unit in one outlet and new mechanical gauge in other.

Richard

 

[--weezl--]

it's funny, i've got a scangauge type deal in my truck, i watch the water temp rise and fall, it sits dead center over a good 20-30 degree variance, then i'll watch it rise 1 extra degree, and all of a sudden the gauge goes from the 1/2 mark to 3/4 mark, then 5-10 more degrees (i forget exactly which) it jumps an extra 1/4 of the way up... i found it quite funny that the dash in my truck (albeit 07) was not at all a direct linkage...

 

[coopab]

Unplug the sender and see what it reads. Then ground it and see waht that does.

Since I posted I've replaced the sending unit...no change. But when I unplugged unit I discovered that the wire was hanging by a thread so yesterday I took the pigtail apart and soldered an extension so I could have a solid connection. Still no change.
Plugged in the needle is pegged as high as it can go but unplugged the needle drops to the mid-point and the check gage light comes on. Grounding the wire gives the same "pegged needle" result as plugging it into the sending unit.
Seems like my 'long term memory' about gauges is telling me that there's a short somewhere in that circuit.
I don't trust mechanical OP gauges so I'm leaning toward an aftermarket electrical OP gauge.
Problem is that there's no convenient flat surface on the dash for installation. In fact the only place I see that might work is on the lower dash panel with some sort of fabricated box to make it visible from the driver's seat.
If the problem is a short in the wiring harness where would sending unit get power?

Coopab

 

[Earl43P]

Set the needle to the 0 peg with no power on.
That should make it read about mid-scale when the oil pressure switch is closed (>7psi)

 

[coopab]

Set the needle to the 0 peg with no power on.
That should make it read about mid-scale when the oil pressure switch is closed (>7psi)

In the original post I mentioned having done the above

One of the quirks about my "new" 99 Ranger with 4.0 was that the oil pressure gauge needle was on the wrong side of the peg. Today I pulled the dash apart to replace the 6 burned out dash cluster light bulbs. While in there I slid the needle off its shaft and replaced it with the needle resting on the peg.

When I got the truck the needle was on the wrong side of the peg and so didn't move at all whether the engine was running or not. When i slid the needle off its shaft and moved it to the other side of the peg I place it at the bottom of the scale, resting on the peg.

I was wondering if I took the dash apart and reassembled it with the acrylic dash cover OFF and the needle removed from the shaft, if I then started the motor and placed the needle back on the shaft at the middle of the scale, would it remain there when I shut the engine down, or would it "rotate" itself on the shaft back to where it is at present or would it merely "settle" down on the peg?

 

[coopab]

Oil pressure gauge revisited

In the original post I mentioned having done the above

When I got the truck the needle was on the wrong side of the peg and so didn't move at all whether the engine was running or not. When i slid the needle off its shaft and moved it to the other side of the peg I place it at the bottom of the scale, resting on the peg.

I was wondering if I took the dash apart and reassembled it with the acrylic dash cover OFF and the needle removed from the shaft, if I then started the motor and placed the needle back on the shaft at the middle of the scale, would it remain there when I shut the engine down, or would it "rotate" itself on the shaft back to where it is at present or would it merely "settle" down on the peg?

I eventually "solved" this issue by relocating the needle on the gauge shaft and it has pretty much worked (such as it is) for the past year. Lately it is gone bonkers again and drops down to the L mark causing the check gauge light to come on, back up to the middle check gauge light off. I keep a close eye on the oil level since this Ranger is long in the tooth and probably a candidate for a rebuild at some point. However....

In the short term has anyone modded a dash to install a mechanical OP gauge? If I install a mechanical gauge with a tee, keeping the old OP switch intact, would the electrical gauge still be subject to the wonky performance?

 

[RonD]

1997 and new oil pressure gauges can not be converted to read "real" oil pressure.

But the older ones can be converted, and you can often swap out the guts so you can get true oil pressure with your original faceplate and needle.
You would need a real sending unit, PS60 is a part number for a real sender available almost anywhere($15), it is a larger sender so you often need to get an adapter to fit it into the old 'switch sender' location.

The older gauges had a 20ohm resistor soldered across the back of them, you just need to remove this or sold a jumper across it so its out of the circuit.

I would pull the dash again and have a look at how the oil gauge is attached to the face plate, also the degree of travel of the needle, and then hit the wrecking yards to find one that is pre-'97 and that will attaching to your face place.

 

[coopab]

1997 and new oil pressure gauges can not be converted to read "real" oil pressure.

But the older ones can be converted, and you can often swap out the guts so you can get true oil pressure with your original faceplate and needle.
You would need a real sending unit, PS60 is a part number for a real sender available almost anywhere($15), it is a larger sender so you often need to get an adapter to fit it into the old 'switch sender' location.

I think i saw this sender in the Info-technical area. It looks like a brass colored dome. If I swapped out the original gauge and replaced with, say a '95 would I still be looking at a L-H range as opposed to psi readings?

The older gauges had a 20ohm resistor soldered across the back of them, you just need to remove this or sold a jumper across it so its out of the circuit.

I would pull the dash again and have a look at how the oil gauge is attached to the face plate, also the degree of travel of the needle, and then hit the wrecking yards to find one that is pre-'97 and that will attaching to your face place.

Before I crawl down and pull my dash, go to the boneyard and try to find an older Ranger with an intact dash how pre-'97 could I go? I'm guessing '90-'96 although my boss has a '96 with a 3.0 and it seems to have the phony electronic switch type gauge.
What appeals about this solution is not having to find a mounting spot in the center console area and the fact that the new gauge would be where you expect to look to check oil pressure. Also, it would eliminate entirely the phony gauge, where adding a mechanical gauge would mean retaining the hinkyness of the phony gauge and adding the "failsafe" mechanical gauge via the NPT tee fitting. Has anyone actually swapped out a 97+ gauge with an older true oil pressure one?