Just had to replace the original OEM oil pressure sending unit as it was starting to leak and make a mess.
The replacement one seemed to be of good quality, but was not from Jeep.... and after install, well that fixed the leak...but now my psi is like 10 lbs lower both hot idle and cold.
I know I still have a pretty tight motor as it only has 107k on the clock. So what gives? She used to sit at full hot idle at 40-45 psi all day long...and about 65ish under load at full op temp.
And now 30 lbs at hot idle and just over 50 under load.
My question is.....is this the sign of a crap quality replacement sending unit? or do they all fluctuate from unit to unit?
At the end of the day yes I do have oil pressure...but it just bugs me that the aftermarket one indicates so much differently than the original OEM one, even though it was starting to leak.

 

IMO tough to say cause you only have 107K on the clock but the OEM one sounds a little high.
To me the replacement seems to read a little more where I would expect it to be.
But I'm just guessing here.
Where was the OEM one leaking out of?
Could it have been leaking just cause the thread sealant had deteriorated some?
Remember these are all pipe thread.
I think you are OK but maybe throw a mechanical gauge on her to check if it really bugs you.
I would just cause OCD is a *****. But that is me. LOL.
In my '00 I had to replace mine. All of a sudden was pinned all the way to the right. All the time.
I used Napa one and want to say it pretty much read the same as the first one before it screwed up.
Also guessing that it was the original one but to be frank just threw it in the box of old parts never really looking at it.

 

Original sounds like it was high.

 

For under $20 you can pick up a quality mechanical gauge, and in less than 10 minutes you can swap in it, verify your pressure, and swap it back out.

 

Ditto. Sounds like it was reading high and now reading normal.

Did it read that high when it was brand new? I could imagine, from the way they are built, failing to report low and just being high.

When mine had its catastrophic failure and started spewing oil it always read way high. But when it was working (and when the original was working) it read like your new one.

 

Thanks everyone.... just out of curiosity... what makes everyone say that the OEM one was reading a little high from the factory unit compared to what I'm seeing now with the replacement one?
For our 4.0's that only has 107k on the clock.... So for a plant with that few of miles, what is average good oil pressure? And on the other side... at what point psi-wise is there cause for concern?

 

I can't say exactly where it was leaking out of, but I know the whole bottome of the sensor was soaked and when I unplugged it the whole inside of the connector was full of oil too.

 

The senders originally and as replacements were unreliable at best.

Try testing it like this and see if you can get to sleep without counting sheep.

 

If mine with only 137k had 30 psi hot idle I would be happy. Hell if mine had 15 psi hot idle I would be happy!

 

Test 'em fellas!!!!

 

Already hooked up my gauges and yes 9 psi hot idle 54 down the road at operating temp. No noise yet so just gonna drive it till it complains....or I finally get my shop built that I have been planning on doing for uh like 30 years lol!
Oh already tried the pipe cleaner trick also.

 

You'll be fine for another 30 years. The 4.0 needs very little oil pressure at idle. I think spec is 9 to 13 pounds at idle. How accurate is your gauge?

Drive it.

The test I was referring to was the ohm test to see how accurately your dash gauge and sender match up.

 

My OTC mechanical gauge and the in dash gauge are within 2 psi of one another.

 

What brand oil filter are you using?

 

I'll have to look when I get home but no worries not a Fram either its a motorcraft or puralator I think.