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oil pressure?

646 views 11 replies 8 participants last post by  JustinH 
#1 ·
oook...For about a year now, I've been having little issues with my oil pressure gauge wavering around. Last spring I took the car to the dealership shortly after first noticing the gauge moving around and they told me the actual pressure was in spec and they never saw the gauge move. Of course on the way home from the dealership the gauge moved around again, but I dismissed the whole thing as a bad sending unit or gauge. I replaced the sending unit with a generic AutoZone part and it didn't do squat, so I assumed it was the gauge or wiring harness.
About a week ago, it started dipping so low that my check gauges light would come on, and that's just too annoying to deal with, so I decided to run a full set of tests on the circuit to see where the problem really was. Here's what I found:

Key on: Gauge drops to nothing. ok...good so far.

key on with circuit grounded: hmm..uh-oh. Gauge reads slightly above midpoint right on the "M" in norm consistently. It hasn't been there in a LONG time.

It seems the gauge and wires are fine, but now I'm faced with this question. Was the sending unit I put in to fix the problem also no good, or am I actually having oil pressure issues?

I haven't noticed any bad noise or anything from the engine, but I am a little sketched out by the fact that the gauge tends to drop when I rev up the engine to 3k or so in park.

Is there any other easy testing I can do other than replacing the sending unit with Motorcraft part?
 
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#6 ·
Hmm, fake gauges suck, IMO! So what I would do is to pull the cluster out, and use an ohmmeter to make sure that the circuit from the gauge to the sending unit is intact. Then, do the mod in the tech articles and modify the gauge so that it reads actual oil pressure. Or just install an aftermarket gauge and that will be MUCH better than stock.
 
#7 ·
Do the gauge mod. But before you put the sender in the engine connect it to a air line (from a compressor) that has a regulator with a gauge. Be sure to ground the sender housing to the engine. Then run the regulator pressure up in 5-10 pound steps and record where the needle is on the oil pressure gauge in the instrument cluster. Install the sender, and now you know what the oil pressure really is in your engine.
 
#9 ·
I've been having similar problems on my '95. The needle keeps going up and down, sometimes turing on the check gauges light, but the aftermarket gauge I have is reading plenty of pressure. I had a thought on my way down to North Carolina today... could an unstable ground cause this?
 
#11 ·
Thanks for the info guys! :) I'd like to get a pillar pod gauge or do the dash gauge mod later this summer if I can. In the meantime I installed a real motorcraft sending unit and it's generally better. I guess this is a good case for not trusting generic AutoZone parts. :)
 
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