It's very close to the oil filter, and it's most likely just a "snap
switch", and the pressure gauge inside the cab is just an idiot light
disguised to look like a real gauge. The "gauge" reads zero on startup,
since it takes a few seconds for the oil pressure to build up and close
the snap switch. Once that happens, the "gauge" will swing to about the
middle of scale and stay there, whether you have 10 psi or 80 psi. Shame
on Ford for fooling people like that!
I'm sure that cost figures into it the most, but supposedly Ford was having a
lot of people compare their oil pressure readings and then owners complaining
that theirs was "low" verses some other guy with the same vehicle.
It is a guage, maybe only a two position gauge, but it is still a gauge.
Without numbers and proper calibraition why is a needle that moves
around any better than a one position guage. They both tell you the same
thing - you have some oil pressure. How many owners even know how to
interpert a real gauge? What is the minimum acceptable oil pressure for
a 5.4L Ford V-8? What is the maximum? How many people worry about the
normal fluctiations in the position of a continuous reading gauge? The
Ford style of oil pressure gauge has one significant advantage over an
oil pressure warning light. It is a positive indication verus the
warning lights negative indication. When the light is not on, you don't
really know whether it is off becasue the engine has sufficient oil
pressure or becasue the light has failed.
If you are one of the relatively few individuals who can actually
interpert an oil pressure gauge, why not install a real gauge?
Persoanlly, I'd like to have an oil temperature gauge.
In that case, it's most likely the snap switch "sender". Replace that
for $5~$10 and see if makes the "gauge" work. Actually. while you have
the sender out, it wouldn't hurt to screw in a mechanical gauge
temporarily to see what kind of oil pressure you're actually getting at
various RPMs & temperatures.
Why even spend $10~$15 dollars for a VOM when you can use a paper clip?
Ignition on, helper in the cab, paper clip in the connector sender
(removed from sender, of course), touch paper clip to engine block; if
helper says that "gauge" needle swung over, it's PROBABLY the sender. If
not, it's probably the "gauge" or the wiring, BUT it could just be
genuinely low oil pressure (< 7 psi), and the engine is slowly
self-destructing without the owner even being aware of it.
Thomas Moats wrote:
I'll agree with using the paper clip as a jumper, but only to a point. I will
not agree with a low oil pressure of 7 psi. The switch will close at 4 psi. Idle
hot pressure will be between 4-8 psi. Hot oil pressure @ 2000 RPM is 40-60. Even
a worn out pump will produce enough flow to close the switch. Worn out bearings
will make noise no matter what. The driver will be able to hear the
"self-destruction". The person who made the post already said there is no noise.
The problem with the "paper clip" jumper is that if you have 0 volts going to
the sender, how would you know it with only a paper clip? How are you going to
know if it is a broken wire from the gauge to sender? How are you going to know
if the gauge is receiving power? If I'm going to spend 10-15 dollars, I will
spend it on something I can use and reuse. Spending any amount of money no
matter how small or large on a part for "diagnoses" purposes is foolish. You
would raise holy-hell if that is how your vehicle was diagnosed in a repair
shop, now wouldn't you? I can see it now........ we replaced the sender it did
not fix the problem, we will now replace the gauge and let you know how it turns
out.If that does not fix it we will replace the instrument cluster, that has to
As I said, if the "gauge" moves when grounding the wire, it's probably
the snap switch sender; it would just about HAVE TO BE, since that's all
the sender does, establish a ground. So then you replace the sender, no
big deal. After replacing the sender - WITH continuity previously
established - and there's still no response with the fake "gauge", you
either have a defective new sender (unlikely), or there's no oil
pressure at the pressure port. You still want to keep your VOM
holstered, and instead reach for the mechanical gauge and hook that to
the pressure port. If you get normal pressure readings with the
mechanical gauge, THEN you can "draw your VOM". Actually, it may then be
time to reach for the wrench set.
BTW, I really have no problem with the idea of an "idiot light", or a
gauge that is actually a gauge (I have both, on all 3 of my vehicles),
with or without numbers; just with an idiot light disguised as a gauge,
telling the driver that there's 40 psi or mid-range at highway speed
when it may really be 10 psi and the engine's main bearings are about to
kiss the crank or, in the case of a malfunctioning oil pressure relief
valve, over 100 psi, and the rear main seal is about to depart the
Thomas Moats wrote:
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