2002 Explorer Useless Oil Fault indicator

This is a 2002 Explorer with a 4.6L V8.

I just had another oil level surprise. 2 1/2 quarts low. Nothing to give any hint of a problem (dash indicator) which really irks me.

I don't know if this lack of any indication a typical problem or just something unique to this explorer.

Some history...

I purchased this explorer used back in 2007 with 80K miles on it. Within a week of taking delivery, it was running odd. I don't remember what it was I noticed, but there was no indication of any oil problem. I did a basic fluids check and found the oil low. Had it towed back to the dealer and they said the oil was radically low and that the engine was shot. Used car dealer honored their warranty and replaced the engine with a salvage yard engine. That ran fine. I was concerned about lack of low indication, had oil pressure switch checked out with the replacement engine and all was fine. It never crossed my mind I would have to check the oil before the end of my first tank of fuel.

About 70K miles later in 2011 I was making a left turn, no hint of engine problems I heard a distinct tap tap tap (just three). The fake pressure guage hooked with the switch never moved off center. I checked oil at my destination just a mile down the road. The oil level was not showing on the stick. I poured a quart in, still nothing. I put a total of four quarts in and just got an indication on the bottom of the stick.

And too late, while it had not made a single extra tap between that turn and when I stopped, after having gotten oil in it, the tap returned and got worse and worse and required major engine work again. And why was it that low on oil to begin with? Apparently at the last oil change I had done they torqued the oil plug too much and stripped it so it was leaking slowly even when I wasn't driving it. Parked over dirt with other oil marks I didn't pick up on it.

So with this last instance, is there some indicator missing that might signal before it gets so low? Or is the oil pressure switch set at such a low pressure threshold as to provide zero warning before engine damage?

On one of my old BIIs it went thru oil and if it got low, at idle with the engine hot I would see the red idiot light flicker. I once even had an oil filter spring a leak squirt the oil out so fast that just seconds after the first flicker of the light all the valves were tapping away. Far worse than anything I heard out of the 4.6L and putting oil back in, it was fine. I guess the 2.9L just let me be sloppy in a way the 4.6L (or any other car/engine) I've ever had.

I know I am far from good with this stuff, but I know I am better than many. Shouldn't an idiot light (or idiot gauge as in the case of this explorer) provide some useful benefit for an idiot?

On our 99 Ranger we plumbed in a actual gauge to read in parallel with the idiot gauge because it kept not-reading anything at times.

Would doing this be any benefit with the 4.6L? If it was down a couple quarts would that show in an actual gauge? Or is the engine design such that pressure alone is not a good indicator of the lubrication status and it again be possible with this 4.6L to see no abnormalities in pressure and suddenly get tap tap tap?

If there is benefit, we will figure out how to get a real guage in there.

If there should be another warning or maybe the pressure switch is insensitive, that be good to know.

I check my oil weekly on vehicles I know, daily when they are new to me. You CANNOT rely on an oil pressure gauge, whether it's a real pressure sensor or just an idiot light because by the time it shows a problem it's too late, as you have found out.

Richard

An oil pressure gauge or light is good to have but as alwaysFlOoReD said, when it shows a problem the damage has started, even immediate shutdown of the engine doesn't always prevent damage.
And generally you "hear" an oil pressure problem before you see the guauge or light, so.......

What has been used for years and seems to work fine is an oil level sensor on the oil pan, I am surprised your 2002 doesn't have this.
This would turn on a light when oil level was down about a quart, so before any damage could occur.
If you do have that "low oil level" light on the dash then sensor on the pan might be bad or bulb is burned out, it should come on with the key then go off if oil level is OK.
Or you could retro fit one.

I guess I just got lucky for many years for all the times low oil level either caused a light to flicker or resulted in tapping I didn't have major damage till this explorer.

I don't know if I have every had a vehicle with an oil level sensor. I always thought the oil lights on the vehicles I had were wired to pressure switches.

If this Explorer is supposed to have one it certainly isn't working....

Yes, oil light would be from a pressure switch, below 5psi closes the switch so light comes on, engine running with above 5psi oil pressure opens the switch so light goes off, so oil light should come on with the key and stay on until engine is started, and psi goes above 5psi.

Ford oil gauge also uses a switch but it is the opposite, it is open with key on engine off, starting the engine and getting above 5psi cause the switch to close which powers the gauge and it shows "normal" oil pressure.
If this type of gauge changes needle position you probably have a problem with the alternator or battery, lol, voltage change would change needle position

If you have both then oil light would be on a relay.

Found an interesting post at another forum, hope link is OK to post here.
http://www.explorerforum.com/forums/showthread.php?t=283383

There is a link in this thread for another thread with pictures of the wiring issues on this model.

If you are not going to check it with a dipstick you may as well just wait for it to make noise before you worry about it. An oil pressure guage no matter how it is activated won't be any more accurate of a way to measure oil level.

Thanks for the link Ron. It definitely isn't an issue on mine, but mind has suffered another issue related to the wiring harness. I work with wiring quite a bit and it has amazed me how much wiring harnesses in many things have migrated to thinner gauges and been subject to breakage.

85_Ranger4x4 said:

If you are not going to check it with a dipstick you may as well just wait for it to make noise before you worry about it. An oil pressure guage no matter how it is activated won't be any more accurate of a way to measure oil level.

Click to expand...

Agreed. I just wish for a something to give a clue the oil level is grossly off (like 2 quarts or more down) before catastrophic damage like every other vehicle I have ever owned before this Explorer.

The difference between your old BII and your 4.6 Explorer is that the 2.9 in your BII had an actual oil level sensor in addition to the pressure switch, and so if you got a quart low the level sensor would flip the light. Your 4.6 doesn't have a level sensor. You gotta check the oil manually.

The level sensors were deleted to remove a point of potential leakage.

You know, I can imagine you guys muttering to yourselves "why she keep going on bitching about the sensor to protect herself from her own stupidity, just check the damn oil!!!". lol

I guess having driven mostly older cars in the 100K+ mile range that leaked oil (and I am sure burned some too) where I was always was having to check and add oil plus several catastrophic events causing oil loss quickly, I just got so many reliable secondary hints that I had low oil and never lost an engine to low oil whereas this Explorer just silently gets into trouble. Doubly so because it doesn't routinely lose oil. For two years it hasn't lost enough oil between changes that I had to add any, now suddenly out of the blue it is down. I suppose it starts sometime.

adsm08 said:

The difference between your old BII and your 4.6 Explorer is that the 2.9 in your BII had an actual oil level sensor in addition to the pressure switch, and so if you got a quart low the level sensor would flip the light. Your 4.6 doesn't have a level sensor. You gotta check the oil manually.

Click to expand...

I hadn't known this, but it is good to know. It does explain one mystery I had many years ago in my 88 B2 as well. I did once get a light that came on in the central area indicating to check oil. I had never seen that light come on before or after. The shop manual says it should come on when turning ignition to start as a "bulb prove out". In the 87 B2 I have now I can see it in the stencil lower right, but it definitely does not come on momentarily for a prove out and I never remembered that in my 88 either.

In any case, the light in the B2 that gave me hints oil was low (by flickering momentarily at low idle) was the one wired to the pressure switch, just once it was that oil level sensor.

Before I got my original 88 B2 I was driving a 72 Chevy Malibu and 79 Buick Regal, both of which leaked oil like a sieve and gave similar hints in the oil pressure if I let it slip too far. Maybe I just am getting too old and don't understand this newer stuff which is in part why I have liked my old B2s better than any of this newer stuff I have driven.