paragrunt

I have a question regarding my 00 XJ Sport. It has about 99,100 miles on it. As far as engine goes, the only mod is an AEM Dryflow short ram installed in the last couple of weeks. That's not my issue though. I started it and let it warm up a few minutes and then as I was driving down the road, I noticed my oil pressure read all the way pegged to the right at 80. Then I got down the road to my destination, shut it down about 5 minutes and drove back home. I noticed that my pressure was back at about 45-50. At idle, I'm at about 30. I change my oil every 5k with Motorcraft Semi-Synthetic and either a Wix or a K&N filter. I'm at about 1200 miles on this last oil change and checked my oil a few minutes ago. It's very dark, like it's dirty. Any ideas why my oil pressure spiked, or is it a gauge problem? It seems to be running just fine. I'm no mechanic, but I have common sense and access to You Tube.

As of recent, it popped a check engine light and gave me a code for a bad Idle Air Control Valve. I replaced it and the TPS. I actually took a bunch of Q-Tips soaked in brake cleaner and cleaned out the Idle Air Control Motor as it was filthy. I made sure it was dry before putting everything back together. The check engine light went away and it's been fine ever since. I had also ran some Seafoam through the TB and cleaned that gunk out. Today I replaced both the window washer pump motors. I know Jeep stands for Just Empty Every Pocket, but this is driving me crazy. I love my XJ and I treat it right. I've replaced so many parts on that thing over the last few years it's silly. I'm hoping for a 300k+ life out of it. I don't care what anyone says, I still think that the XJ is one of the sexiest SUV's to ever grace the American roadway.

Any insight that any of y'all can provide me with would be greatly appreciated. Thanks in advance.

kgm

Common opinion seems to be the gauge is junk. You can also replace the oil pressure sender unit as they die. Mine reads seemingly accurate (50 cold/load, 20ish idling hot) but who knows. It's low on my list of replacement sensors.

Does the engine make a-clatter post-warm up? That's a sign of actual oil issues. Mine is relatively quiet (for a tractor) once warmed up, so I don't worry about it. Wouldn't mind putting some 0W40 synth in there for these cold months though.

Glockmeister

This just happened to me a month ago. I changed the oil sending unit and it fixed the problem.

paragrunt

If I remember correctly, it purrs like a kitten. So, nothing to worry about? I'm getting ready to go on a trip over the mountain pass here and really don't want to get stranded.... Is the sending unit an easy change? I'm pressed for time. Arrggg, if it's not one thing, it's another.

I bought it with 64k on it a few years ago. The head had been replaced prior to me getting it. I noticed old oil caked in the coolant neck so we flushed it. Then we replaced the radiator and back flushed the heater core. It had a tune up about 15k ago, new plugs and a new coil pack. I used Champion Copper Plugs, it's had a new thermostat, Optima Red Top, and I put a BDS 3.5" lift on it with 31" Duratrac's. All the seals in the front axle have been replaced. I have taken great care of this XJ. The day I got it, I had the trans flushed, then dropped the pan and changed the filter and refilled with Amsoil trans fluid. Both diffs were drained and replaced with Amsoil. I need this thing to be top or our vacation is kaput.

Ian96XJ

I have the same problem. I'm just replying so that I can catch the follow up replies.

tjwalker

I agree that a failing oil pressure sending unit is the likely suspect. Yes, the gauge is a possibility, but they fail way less often than the sending unit does.

Located directly above the oil filter, the sending units are very easy to change. I highly recommend using a Mopar unit for the best accuracy/reliability/mating with your factory oil pressure gauge.

Before you swap in a new sending unit, inspect the WIRING/CONNECTOR leading to this unit; any intermittent issues could be related to poor connectivity.

ksrummel

Same here cuz I'm in the same boat

salad

Inspect wiring and connector, if necessary replace the sending unit. If you take the sending unit out stick something in that hole to clear out any crud that may have built up.

And OP, that K&N oil filter is nothing special, just a Mobil 1 with a nut welded on and marked up appropriately.

my89xj

X2 on trying a new sensor, that was my issue. I went to the junkyard and got several of them and threw them in my toolbox. Picked the cleanest one and it worked dandy.

paragrunt

Thanks for the replies guys. I called the local NAPA and they have one sending unit in stock. I wish I had known dammit, I live an hour away from any other parts stores and I was just at Autozone and drove past a Dodge dealer this weekend when we went shopping. I hope to hell the wiring is okay. Does this part screw in or just kinda push in? Is my wife doing any damage driving it this way, or is this simply a relay telling the gauge what the pressure is?

salad

No issues driving like that at all.

OPSU screws in.

Glockmeister

Very easy to replace. You will only need a crescent wrench as I think the nut is 27mm. There is a switch where it plugs in. Just click the switch over, unplug then unscrew it and put the new one on. Took me about 20 minutes.

XJPat

Hey guys, my oil pressure sending unit went as well, do I put any type of sealant on the threads on the new one, old one looks like it has Teflon plumbers tape?

Glockmeister

My new unit came with a rubber washer so I didn't bother with sealant. Plus I thought I had some and was out and didn't want to make another trip to the store. It couldn't hurt but mine is doing fine with just the washer.

paragrunt

Thanks for the info everyone. I went and got a new oil pressure sending unit from NAPA and put it in. I started it up and it's between 40 & 45. No leaks either. Mine didn't come with a gasket or sealant, it had what looked like red locktite on it already. Now, I'll probably change the oil and dump some Barsleak Engine Repair in it to treat all the seals. Life is good.