OT: 1998 Ford Ranger Oil Pressure Gauge

 Many of you have forgotten more about mechanical things than I'll ever know,
so here goes ...

(It is cold here.)

1998 Ford Ranger, 150K miles, properly maintained.

Oil pressure gauge read zero this morning when I started the truck, causing
the "Check Gauge" light in the instrument cluster to illuminate.

It had done this once before, and I thought it was the same behavior as
before.  Turned off the engine and checked the dipstick -- I did have oil
(losing my oil somehow overnight would of course be a good reason to have no
oil pressure).  My understanding is that oil pumps are very simple devices
and don't fail.  Between the past behavior and the presence of oil, I
figured I was OK, so I went driving off.  Sure enough, about a mile down the
road the oil pressure gauge sprung to life and showed about the midpoint
(which it usually does).

I normally wouldn't operate an engine showing zero oil pressure, but I was
pretty sure I had oil pressure in this case.

Questions:

a)I'm assuming that I'm probably looking at a bad sensor or gauge --  
anything I should look for that would actually result in zero oil pressure
for a while?

b)Any hints on how the gauge is likely to work or what needs replacing?

Thanks, The Lizard

 Jujitsu Lizard wrote:


I had a 1990 Dodge D150 pickup, that the oil pressure gage
dropped to zero 300 miles from home.  That shook me up, pulled
over to the side, checked oil.  level was proper.  A little more
cautious, I made it home safely without further stopping.

Oil pressure sending unit had failed. After replacing, it worked
fine.

First, I would check wiring, to be sure there was not a poor or
loose connection.  Sensors aren't that expensive, and with that
many miles, replacing it would be prudent.

Oil pumps are normally mechanically driven devices.  It is rare
that they fail.  Instead, oil pressure may degrade over time due
to increased slop in badly worn bearings or badly worn pump,
causing pressure drop.  It is also possible that check valve
balls can stick.  If oil changes were faithfully maintained (and
hence a good reason to do so), I would suspect the sensor.

It is possible that the gage itself is going bad, but from what
you describe I doubt it.

I put 246,000 miles on that 3.9 L V-6 and it was still
maintaining proper oil pressure the day I got rid of it (with the
new sensor of course).

--
HPT
Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

 Jujitsu Lizard wrote:

Are you David T. Ashley?

 nasty milo wrote:


Isn't that obvious?   ;-)

--
   -bts
   -Friends don't let friends drive Windows

 
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