The oil pressure gauge on my '94 Ranger STX/ (4.0/ 5-speed stick) does some weird things. It starts out in the low to normal range, but gradually creeps higher as the truck warms up. By the time I've reached the end of my 30-mile commute, the needle is usually pegged on the "H" or high mark. Sometimes it will remain in the normal range, but at the very top end of it. Going home last night, snowy with truck in 4WD, the temp gauge climbed to the high end of the normal range (which it's never done), and oil pressure gauge was totally pegged. Engine otherwise seems to run OK. Dealer says it's PROBABLY a faulty sending unit, don't worry about it. If it was the sending unit, I wouldn't think the gauge would gradually creep up- it would just shoot to the top, IMO. Any ideas?

 

Mark, I thought the '94 models came with a dummy gauge, no? (I could be wrong).

You might find some useful info here:

http://www.rogueperformance.com/oilsw.html

 

Rockledge, I know what you're saying, but those gauges (the "dummies") immediately jump to the center as soon as you start the engine. This one starts out low and gradually rises to the top of the gauge, as though it's actually "reading" the oil pressure. I don't think it could do that if it was the "dummy" gauge.

 

Mine did! Not just once. Had trouble getting one to last 3 months.
Even lost an oil pump before getting a low pressure indication. Cost me $900 to rebuild it myself by the time I got out of the woods.(hunting)
Finally went to the sight mentioned above by Rockledge.
$6 latter I have a real working gauge.
If I could recommend only 1 thing to anyone, It is "DO THIS FIX!"

 

Is there a chance that the previous owner may have already done the switch assuning there was a previous owner.

 

I believe that there is a voltage regulator that drives the temp, and oil pressure gauges. This voltage regulator could be going bad, or you have a bad ground connection on your instrument panel. A single sensor going bad should not effect both temp, and oil pressure....