View Full Version : WA's Dumb Farm Truck Q's, Part 7k: oil pressure gauge

War Admiral
Nov. 7, 2009, 10:29 AM
OK, help, please, kind COTHers, this isn't very clear in the owner's manual: my '94 F150 has an oil pressure gauge. Last couple days I have noticed the oil pressure gauge tending towards the low end (it's still safe according to user manual... a fraction below the midpoint but still well within "Normal" range). Where SHOULD it be reading if all is well? Midpoint? Higher than midpoint?

...Yes, I'm going to check the oil. ;-) No oil leak that I can see. What else, besides that, would cause the oil pressure to drop??

Thanks for any feedback!

Frank B
Nov. 7, 2009, 09:25 PM
Possibly the oil pump is wearing out, the screen on the bottom of the oil pickup is becoming clogged, the gauge and/or sending unit is faulty, or there's low voltage on the electrical system.

Is the electrical system volt meter reading the same as usual? If it's low, it could cause the oil pressure meter to also read low.

It would be a good idea for a trusted mechanic to take a look at it. The oil pan would have to be dropped to check the first two possibilities.

War Admiral
Nov. 8, 2009, 07:44 AM
Thanks so much, Frank! Will do.

Wooly Wintertime
Nov. 8, 2009, 11:52 AM
I had one of the same style F-150's with a 351 Windsor. Loved that truck. Unfortunately it had been pretty well used and over time main bearings went. It had *very* low oil pressure. But I think what Frank B said rings pretty dead on. A faulty sending unit seems to be a fairly common diagnosis anyway. Good luck!

Nov. 8, 2009, 06:01 PM
Faulty sensor/sender
Worn pump
Worn main bearings $$

Tom King
Nov. 8, 2009, 11:01 PM
Oil pressure is a good thing.

Nov. 9, 2009, 07:13 PM
Generally bearings.

How's the temperature/water temperature? Higher operating temperature will thin the oil and lower pressure, particularly if you're running pretty hot. That in term will lower lubrication and contribute to bearing failure.

Get it analyzed. Bearings are expensive, although pretty easy to replace, but not as expensive as turning/new crank, etc. A repair now might save a new engine later.

Nov. 9, 2009, 08:51 PM
Do you have weather? I mean, Weather?

You get different pressure readings with cold vs. hot.

The guage went on my Dakota. that was an easy, cheap fix.

But definitely have it checked, as said above.

War Admiral
Nov. 10, 2009, 11:12 PM
Thanks all, will do!