randomXY

I've read lots of threads on oil pressure gauge readings and I thought I had it figured out but apparently not...

Background: 1999 Cherokee Sport, 136K, 4.0L and bought it about a month ago. Last couple of weeks noticed oil pressure at idle hovering at 40. With mild acceleration would run up to near 80. Not sure if that was a change or I just hadn't noticed before purchasing.

With no change it just pegged itself at about 60, when starting, running, accelerating - whatever, it just stayed right around 60. Lots of forum searches it sounds like a good candidate for a NEW oil pressure sensor. Got one from NAPA, installed today and now the oil pressure stays right around 50 - at idle, driving, accelerating.

Any thoughts on what might be the next thing to investigate?

Few things:

• Haven't done a manual oil pressure check because none of the stores near me rent one. Prefer not to buy a tool I'll only ever use once.
• Engine seems to run fine but I have no baseline of how an XJ should run.
• Given it runs OK, I know its most likely not an issue but all the same I'd like to fix it

Thanks!

4WD4EVER

If you really want peace of mind knowing what your oil pressure is you need to borrow or purchase a gauge to manually test; there's no other way. It is the best and most reliable way of settling the issue once and for all and taking the guesswork out of it.

It's either that, or, you can chase ghosts and never settle the issue in your mind.

Your choice.

GreaseMonkey17

I'm confused by your post . Are you wanting to investigate the accuracy of the oil pressure sensor or do you think you have low oil pressure ?

nujeepguy

50 running sounds good.
but ive never seen an oil gauge read steady with no change when idling hot/
mine drops to 30

randomXY

GreaseMonkey - I don't think it's the sensor. Both the new sensor and the one it replaced just give a steady reading. Turn it on cold it goes to directly to 50, hard acceleration it sits at 50. (old sensor sat at 60, new sensor sits at 50 - nothing else changed).

It runs fine but it seems really strange to me. I will get an oil pressure test kit on it at some point, just looks like I'll need to suck it up and buy one.

GreaseMonkey17

I'd say you have nothing to worry about but seeing the actual pressures will certainly give you peace of mind ! Sometimes that's all you need , myself included .

freegdr

Just turning key on it goes to 50 ?

XJeepCheep

Get a set of cheap aftermarket Manuel gauges and hook up the oil one to test. Could be your dash is just off. But unless it's low I wouldn't worry.

moparado

My oil psi instantly goes to 55+ with an overnight cold start.
Hot engine at freeway speed, its around 50.
Hot engine, @15mph to highways speeds, a solid 50.
Hot idle, its around 27 to 30+ depending on hot or cold weather.
I'm running rotella 15W-40 oil.

Does this also include hot idle?
Are you saying the cluster gauge is always at 60 even with the engine off?

If its reading 60 at hot idle then there's something going on.
Like mentioned, you need to hook up a mechanical gauge to cut troubleshooting the problem in half.
Either its on the pump/sending side.
or
The instrument cluster side.

randomXY

At hot idle it sits at 50. Lately it might drop to 48 when driving but mostly just hanging out at 50 no matter what I'm doing.

With the engine off the needle drops to 0, so at least I know it's not stuck

I'm going to get a mechanical gauge on it shortly and will update this thread with the outcome.

freegdr

Unplug sensor turn key to run whats it read ?

PoorMansWrangler

Oil pressure sending unit is a quick fix