My Oil Pressure gauge normally gives a reading between the "R" and the "M" on the NORMAL indicator. However, for the past couple of days, it has gone down between the "N" and the "O" and even sometimes right on the "N". Although this is still technically in the "normal range", I am a bit concerned as to the cause of this. I checked the oil level and it was a bit low so I topped it off and drove about 50 miles or so and it is still reading on the "N". What are some other causes of low oil pressure that I should check into? Any help would, as usual, be much appreciated!

 

my 90 Bronco 351w dos the same thing every once and a wile drops between N and the O but it normally gives a reading between the "R" and the "M" than after a few starts or some times wal i am driving it gos back to were it is normally i am sick of it i am just going to put a auto meter gauge in it and i have replaced the oil pressure sending unit still dos the same thing.

 

Guys I may be wrong about this, but I remember hearing on "Cartalk" a few years ago that the factory oil pressure gauges on Ford trucks during the early and mid 1990's were not truly displaying oil pressure, the gauge just activated when the motor started and would sit somewhere in the middle (between the "R" and "M"). Can anyone else confirm or deny this?

 

My 93 is just that, an idiot light that looks like a gauge. It's easy to tell, just look at the pressure sender on the block. If it's a small sender it's really just an idiot indicator. If it's the large sender it's probably a real gauge

 

Where might I find the pressure sender? Also, how large is large, and how small is small? Thanks.

 

I got my oil pressure-sending unit at auto zone it is a Bog Waner part. It is right above the oil filter I think it is a 1 1/16 deep socket it is about the size of a 1/2 role of lifesavers. Takes about 10 min there is only one wire going to it's really simple.

 

I do not have the oil pressure guage on the inst. cluster but I do have an aftermarket guage. I have an 83 351w and after its wormed up it idles at about 50 psi.
For some reason right after I got a timing cover leak fixed the pressure after being on the highway for a bit (and sometimes randomly) will drop to 20psi at idle but will go back up once i touch the gass.
I was told that 20psi is normal at idle and a mechanic told me that the older 351's only need 7psi to run alltho another mechanic said that sounded a bit low.

As for the 90's trucks only having a warning guage kinda makes sence. You know how Ford and there infinate wisdom is.
If you are worried about it get a mechanical guage or the part 91F-150302 is talking about.

 

I'm thinking it might have something to do with oil temp and/or viscosity maybe. When I first start my truck up after sitting a while it goes to the "R" now, but after driving it for a bit it goes back down to the "O" or between the "O" and the "N". Also, the colder it is when I start my truck, the higher the reading is. I know that when things are warmer, they are less viscous (usually) which means they flow easier which would mean less pressure. I may be way off here and may be reading to much into my oil pressure readings, but it just kinda seemed to make sense. But I wouldn't know what could be wrong except for switching to a more viscous oil, but I don't remember it being too much of an issue in the past. I will look into getting a better gauge, too.

 

your gauge isnt a gauge, its either on or off, the sending unit is simply a pressure switch and is not variable. i would say dont worry about it until you have a more accurate means of reading the oil pressure.

 

TF.
Slap one of those Auto meter pillar gauge setups. Put in a mechanical oil pressure gauge and a mechanical water temp.
It will be nice and accurate ... No questions asked.
Take a look at some off my pics.....I should have 1 or 2 pics of gauges in there ......LOL!

Jerry D.

 

That's a good idea. I was planning on doing oil pressure/water temp/tranny fluid temp when I get my tranny rebuilt, but I don't suppose this is a prerequisite. I'll probably get these guages as soon as I get a couple extra bucks.