My 94 2wd 302 cid EO4 Trans, Has always had eratic oil pressure readings, Ive used heavier wt oils and different brand filters, It will go for months at mid guage readings and then it will move up and down eraticly and stay at the lower end of the normal range. Some of my friends 302's have really low guage readings as well but dont fluxuate as severe as my 302. I really hate to start replacing sending units, wires,and guages. I dont believe the motor actually has low oil pressure. If anyone has had a simular problem and can lead directly to the problem I would greatly appreciate it.

 

I've got the same problem in my truck..which is just like yours...I read a topic on this site a while back that mentioned the fact that Ford's Oil Pressure gauges are very inaccurate it's almost a scam. I just make sure I check my oil everytime I put gas in and keep it up to the level it's supposed to be at. I have a bad oil pan gasket so Im constantly adding oil because I can't afford to have it fixed and I definitly can't do it myself. I guarantee that this Ford I have will absolutely be the last one I buy forever.

 

I have owned at one time or another all the Major automakers trucks, They all have their faults, I'll openly admit that I'm a ford fan and this 94 f150 and my 92 f150 have had more than their share of problems with oil leaks, oil pressure, and keeping a tranny in one is a joke. Even with all that, Fords are hands down better than Chevys or Dodge's.

 

All you guys need to do is to get some 1/4"x3" brass tube with npt on both ends, a "T", some teflon tape and a mechanical oil pressure gauge.


Take off the sending unit (or sensor) from the block. Install the
3" brass tube, the "T" with the single outlet to the side. Mount the sending unit on the extreme end and the fitting for the mechanical gauge on the side. (face the "T" so the side fitting is at 1:30-2:00, or facing up and to the rear). ALL JOINTS sealed with Teflon tape.


Mount and install the mechanical gauge as per instructions.

Run up the engine and take readings, at idle, 2000rpm, 3000rpm, and 500 rpm below indicated "REDLINE" on tach.

Run down the road for about a 1/2 hour (get the engine hot) and retake readings .

These will be your nominal readings. Compare with "BOOK" pressures. They should be comparable.

In any event, pressure should corelate to 10 psi per 1000 rpm.

Larry
:-X12

 

Thanks Larry, I'll do that to compare readings .

 

I think that it should be much higher that 10psi per 1000rpm. My 302 does that same fluctuating thing and I checked the oil pressure and found very low pressure. It's like 1.5 psi at idle. Anyways you can buy a guage from sears or whatever to check the actual pressure without gutting your stock unit.

I believe that the stock range for the 302 should be around 10-15 psi at idle and at about 50 psi at 2500. Check a book to make sure though!

 

My 92 302 had a fluctuating oil pressure reading on the guage. I pulled the wire off the sensor and grounded it. The guage then read over half way which indicated that the guage was good. I replaced the oil pressure switch (just in front of the oil filter, hard to reach, 27mm long socket required) and replaced it with a new one. The reading is just over half way now and steady at idle or cruising.

 

Thanks for the input, next time I change my oil I'll replace the sending unit amd see if that helps ....Thanks again.

 

There were a number of posts on this subject several months ago. It was reported in them that the oil pressure gauges used from '87 (I believe that's the right year) on were actually "Idiot Gauges". Specifically, anything below a certain pressure point (say, 6 - 10 psi?) caused the gauge to read in the "Low" area, and anything (that's ANYTHING) above this amount caused the needle to automatically spring to the "Normal" range. Essentially, they have the same function as an idiot light, but you have something that looks like it's more sophisticated. Supposedly, the differences that appeared in the needle's reading (say, at the "N" as opposed to the "M" or "L" in the "NORMAL" range can only be attributed to various electrical fluctuations not specifically related to actual oil pressure. The poster went on to suggest installing an earlier sending unit (out of, say, an '84 truck or other Ford truck) and/or installing a resistor on the backside of the gauge to correct this sin of engineering. Anyone recall this, or any related details?