Oil Gauge in dash reading very high

[94blu4x4]

Gauge layout is: L normal H

I thought the oil gauge in the dash just read in the middle of normal (rm) unless it got low on oil then would drop down toward the N side of normal and low oil light would go on.

I my case just regular driving the oil gauge reads to the right of middle and after 20 min of driving will be creeping up to the L in normal and at times go to the right of normal toward H on the right of the gauge.

Any idea why? Does burn some oil, but not blowing smoke out the exhaust. Has decent power and no oil in coolant or creamy oil either???

Thanks

 

[Scott B.]

You don't have real oil pressure gauge. It is a shunted gauge, that shows only 3 states - none, low, high (or normal.) On top of that, these motors are known to lose oil pressure as they age (it's scary seeing how little oil pressure my 300K mile motor has!)

There is a way to convert your in-dash gauge to show real pressure - search on this site, and you will find it. In a nutshell, you need to replace the 20K resistor shunt on the back of the instrument panel with a wire, and replace the oil pressure sender on the engine with a true pressure sending unit. Not difficult, just time consuming.

 

[Maniak]

A couple things..

The resistor on the back is a 20 ohm, not 20k (ok, I'm nitpicking, its the only one that says "20" on board next to the resistor).

The factory sending unit only has 2 states. Open and closed. When the oil pressure is below 5psi the switch (sending unit) is open which makes the gauge read 0-ish..

When the pressure is over 5psi it closes the switch and basically takes that wire and shorts it to ground (to the block). If there was no 20 ohm resistor the gauge would peg at that point. The 20 ohm resistor makes it go into around the center of the gauge.

With the needle creeping up the resistance/impedance of that wire/circuit must be going down OR the reference voltage is changing. I've heard that there is a voltage regulator on the back of the cluster, but I don't know much about it.. never had to deal with it.

Are any other gauges moving around at the same time? If the voltage is having issues usually the fuel gauge will move too (go higher)..

Normally, a resistor will increase its resistance when its going bad, not decrease it which is what it is appearing to do.

Personally, I would short out the 20 ohm resistor and put in a real sending unit and start from there..

Here is the light reading when the conversion was first done.. even has part #'s.

http://www.explorerforum.com/forums/showthread.php?t=65575&highlight=oil+pressure

~Mark

 

[94blu4x4]

Thank you for the advise, my search ability is clearly lacking. Mostly concerned that I was having an issue like sludge that could have blocked something causing the higher reading.

At least I know where to start looking if I dig into this further

take care