Sudden high oil pressure '99 4.0

Hi all,

am a bit stuck here... '99 XJ, 4.0... I'm actually at my friend's shop right now (50 miles from home of course) planning on installing a new muffler in preparation for getting the vehicle inspected. I ran up the street to get a pair of tires for him and while driving down the road I noticed that my oil pressure was much higher than it used to be - it's always been 45-50 PSI at any RPM off idle. Now it's 70 PSI going up to peg the gauge when I increase RPM. I pulled it in and removed the element from my filter (I'm using a CM racing filter) thinking that perhaps my element was clogged, no change.

Questions:

1) Where *is* the sending unit, hydraulically? Is it between the oil pump and the filter, or is it after the filter? (pretty much irrelevant now that I've ruled out the filter as the problem, but I'd like to know.)

2) Where is the oil pressure relief valve on the 4.0? Is it serviceable from outside the engine?

I really don't think that I have a problem with a blocked oil passage as the inside of the head was clean enough to eat off of when I replaced the valve cover gasket, and ever since I've been running Rotella or Delo synthetic with a CM 8 micron filter element.

Any ideas for troubleshooting without spending $50 on an oil pressure test kit, or at this point do I need to just suck it up and buy it? (It's frustrating to me that I am stuck at a professional shop and they don't have one, but that's another rant for another time.)

thanks for any ideas...

nate

Check grounds and connections for the engine and sending unit. Then, yes, I'd measure with a physical gauge to see if there is actually a problem, or just a failing sender.

Ground should be good, I installed Jon Kelley (5-90)'s cables maybe 2 years ago when I replaced the battery. Connections look clean and bright.

the sensor is right there next to the oil filter. likely the culprit.

The pressure relief is in the oil pump.

Dammit, just wasted $54 on an oil pressure test gauge... you are right, on the gauge it never goes over 60 PSI. @#$%@#$%.

Why do I have more/better tools than the pros?

At least when I'm here the parts peeps bring stuff to me. Also, $42 for a damn sender?

I had the same issue. Rock auto.com -- $33 delivered in 2 days.

Well the #$%^#$% dealer didn't send the part...? grr... good thing it wasn't a customer vehicle... ordered from the dealer because the parts houses weren't any cheaper

Fixed. Sender sorted it... now to do the muffler that I intended to do in the first place. (Stuff gets done slowly as every time I show up at the shop it gets busy and I end up working on customer cars...)