Oil Pressure guage drops after highway driving

[skibum2u]

My 91 explorer recently has been having oil pressure problems after a recent oil change. When stopping on an offramp after driving for about 20 minutes my oil pressure guage drops to nothing. Once I apply gas to the accelerator the guage brings itself back up to normal. Generally during normal driving I don't notice a problem unless I have been driving for an extended time.

Is this something I should be worried about and if so what can I do to fix it.

 

[Raceit]

I never really noticed mine moving all that much, but it's just an electronic gauge. A couple of months ago I hooked up a machanical oil pressure gauge. It had a copper tube going to the gauge instead of having a sensor attached to the engine block.
However when I hooked it up it would always fluctuate (sp?) depending on what the engine is doing. At idle (once warmed up) it would go down to about 20psi. On the highway it would hover right around 60psi. And when it was stone cold it would even make its way up to 80psi until the engine warmed up.
I would consider it normal for the oil pressure gauge to move depending on what's going on. I had a Mustang do the exact same thing with a machanical oil pressure gauge.
You can always get a somewhat inexpensive oil pressure gauge from an auto parts store to keep in your cab at least temporily to see more accurately what's doing. Just make sure you get copper tubbing instead of any plastic ones that may come with it.

Hope that helps. And welcome to the board!

 

[Maniak]

Raceit is right.. the Oil pressure guage in at least the first Generation explorers is actually just an analog idiot light. You can easily make it a real guage (or at least closer to one) by changing the current oil pressure switch (small little thing) with one of these part numbers..

NIEhoff brand: FF133E
SMP brand : PS-60
GEN (it is on my box): OP24761

Once you do that you need to pull your instrument cluster out (it isn't that hard).. and you will see a 220 ohm resister marked on the back of the cluster.. just short out the resister and then your old analog idiot light is now a guage.. it will move as the pressure really changes..

Now on to your issue.. I notice you also have a thread about voltage fluctuation.. Here is what I've noticed on our 1992.. When we have a bad ground.. or any type of voltage problem. our guage will go nuts.. It normally got all the way up and stays there.. I tested it with a mechanical guage and know it is an electrical problem since the mechanical guage showed good pressure. Currently our 1992 needs new battery cables.. (they are coroded) and I can clean them up and then our oil pressure reads correct for a week or so.. then it goes nuts again.. and the cables are coroded again.. Now we have a new symptom.. Lights are flickering and if I have the trailer attached.. the turn signal makes the volt guage bounce (which it didn't used to do). The alternator/regulator is good so I think it it our cables doing it.. possibly even the battery (3 years old). This weekend we will change the cables.. and I'll let you know if that fixes the flickering light issue..

but as Raceit said.. get a cheap mechanical oil pressure guage.. if it shows all is good.. then don't worry about it as much.. just fix the electrical problem and it should start to work right then.. If the mechanical guage shows no pressure after the freeway driving.. then worry.. alot..

~Mark