jjfatboy

I've got a 1999 Lincoln Navi with about 93K pampered miles. Yesterday I noticed that oil pressure gauge and light were on at idle. At above 1000rpm oil pressure pops up and light goes out, stays up with no fluctuations until rpms drop below 1000, then gauge drops like you turned of a switch and light comes on. No noises in motor and idle up, gauge pops back up like turning switch back on. Could this be a sending unit or something much more severe? Anyone know were the sending unit is on this big beast? Since the pressure gauge cuts on and off like flipping a switch, could it really be the oil pressure???? if I have a bad pump or bad bearings, wouldn't pressure ramps up and down with rpm, etc...or just cut out for good? Definitely nothing happening when motor above about 1000rpm - gauge doesn't even wobble. Shows slightly over 1/2 on the gauge....maybe even 2/3 of range between H and L. I've run nothing but synthetic in here ever since I got her at about 55K. She has always run like a top, until now.
Jeff

slw2206

I have the same problem only in a 2000 Expedition. I also believe it to be the sending unit and not the pump. As you said the gauge bounces up and down, and if there truly was no oil pressure the engine wouldn't run for long before major problems developed.

I hope you or I get a reply soon as I'd really like to know where the sending unit is and where I can buy one online.

jwko

This is the only diagram I could come up with. I hope it helps



TESTING

1.Test and verify the engine oil pressure. See for more information. If no or insufficient pressure exists, oil pressure problem exists and gauge and sensor are operational, repair oil pressure problem.
2.Check the appropriate fuse before attempting any other diagnostics.
3.Unplug the sensor electrical harness.
4.Using an ohmmeter, check continuity between the sensor terminals.
5.With the engine stopped, continuity should not exist.


The switch inside the oil pressure sensor opens at 6 psi or less of pressure.

6.With the engine running, continuity should exist.
7.If continuity does not exist as stated, the sensor is faulty.

REMOVAL & INSTALLATION

1.Disconnect the sensor electrical harness.
2.Unfasten and remove the sensor from the engine.


To install:

3.Coat the new sensor with Teflon® tape or electrically conductive sealer.
4.Install the sensor and tighten to 11-15 ft. lbs. (15-20 Nm).
5.Attach the sensor's electrical connector.
6.Start the engine, allow it to reach operating temperature and check for leaks.
7.Check for proper sensor operation

wwwabbit

Thanks to ford... your "gauge" is really only an idiot light. It is "on" in the middle, or "off" at low. Was this with a hot motor?
I would suggest an oil and filter change to start with, just to make sure it's nothing simple like that.

naviracer23

I know this is an old thread but I have 00 Navigator and mostly when I start the engine, my oil pressure light will be reading 0 and the warning lights will be on and then it will stay like that and go up to normal usually within a few seconds to a minute or so. Bought a new sending unit tonight and going to install tomorrow to see if that helps.

Some background, this oil pressure gauge problem has been like that for years so I know it is not just related to the fact that my rings must be bad because I just changed the oil 2500 miles ago and checked the other day and it was down to low on dipstick. Put in 3 quarts and it is now full again. I also have an engine knock which Lincoln determined is a bad rod so I will be putting in a new reman engine with forged rods/pistons and be built as apparently this was a common problem with my engine and this engine is currently a reman from ATK with only 67,000 miles.

I would like a more accurate gauge, so could I put in an autometer gauge to get the oil psi and if I did that, would it show a lower psi when oil starts getting low?

Bert

Low oil won't always show low pressure unless it's almost out of oil. By then it's too late.

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Bert

naviracer23

What good is an oil pressure gauge then?

I picked up a new sending unit switch last night and put it in today and as of yet, no problems seems to be fixed. I have a 00 Navigator and it is underneath the vehicle about 3" from the oil filter. There appears to be no way to get it out without removing the oil filter and even then takes awhile to get out due to no hand/tool room to maneuver.

jwko

To monitor the oil pressure.

Looks to me a high end vehicle like the Navi would have a low oil sensor. My old gmc truck does.

AlwaysFord

They do. The check engine light will come on if it gets too low, the PCV system in combination with the EGR system and knock sensor will pick up on low oil and throw codes for all 3 systems if the oil is too low, but at that point you are already hearing some lifters and whatnot. I imagine it takes about 2 quarts low for a clean engine to pick up on it.

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2001 Ford Expedition Eddie Bauer 4x4 (mine)
2003 Ford Focus SE (the wifey)

AussieSean

Realize this is an old thread but I have same problem, can anyone tell me or have a better sketch that shows the location of oil sensor, thank you. I have a 1999 also.