high oil pressure

Hey folks, newb with a question...

The other day, I started my 2000 XJ Sport (4L) and noticed an almost gurgling sound coming from the engine. Loud enough to hear when idling, but doesn't increase in sound when driving. Also, the oil pressure gauge jumps straight to 80 and doesn't move.

After doing some research, I read the usual culprit is the oil pressure sending sensor by the oil filter. If it wasn't for the weird noise, I would have just replaced it immediately. I needed an oil change anyway, so I went ahead and changed it and noticed a slight leak coming from the oil pan gasket, so that needs tightened down or changed. After putting the new oil filter on and driving awhile, I checked underneath again and see a good bit of oil coming from the seal around the oil filter, so I bet the oil pressure really is just too high.

Further research mentions a pressure release valve on the oil pump...maybe it's stuck in a closed position? I bought a new oil pan gasket and figured I could check out the oil pump when I took off the oil pan, but after having a look, it appears to be a bit more work than I care to do, so maybe I'll just take it to the stealership for a diag and have them replace it while it's off.

Thoughts?

Thanks!

i have the same problem, minus the gurgalling and leaking. i think my sending unit is bad, but idk. but yeah i have no clue what your problem is, it sounds like you have it pretty well covered

You can test the gauge with a jumper wire. Unplug the wire from the sending unit and the guage will go full tilt to the right, then ground it with a wire to the body/engine and the gauge will go to zero. When you install the new sending unit, be careful not to crack it or it will leak. Use a socket and don't get it too tight. Also since it's pipe thread, be sure to coat the threads or use teflon tape if it doesn't come with some goop on it already. I got mine from napa and it had goop already. My gauge did the same thing, 80psi. Also, when you changed the oil, did you make sure that the old oil filter gasket came off with the filter? Sometimes they stay behind and when you install the new filter you'll have a pretty good leak. The pressure isn't sudddenly going to jump, there's a pressure relief valve built into the oil pump. My money is on 1 old oil filter gasket still on the oil filter adapter with the new oil filter installed, and 2 bad pressure sending unit. FWIW, they don't leak from the pan gasket, they leak from the rear main seal, o-rings around the oil filter adapter and valve cover gasket.

The oil presure senders from at least 96-later will peg to 80psi+ when they are disconnected or otherwise interrupted.

Hard to say what's going on...it did this for a week but this morning, it ran just fine again. No noise, normal pressure. I'll chalk it up for goblins at this point.

The oil coming from the seal around the filter is most likely the Oil Filter Adaptor...common issue on the 4.0....I just went through this about a month ago on my XJ. When I pulled the seal out it was hard and flat on one section, which is why it was leaking.

Here I thought it was a rear main leak....i'll bet your tranny pan and bellhousing are covered on oil too?

The o-ring set is about $4 from the dealer. Make sure you get the SET, for some reason they sell JUST the main o-ring too....and you'll need to replace the two smaller o-rings on the hold down bolt too.

yucca-man did a great write up that I used and bookmarked. My browers crashed a couple of weeks ago and i lost everything I had saved and for the life of me i can't find it anywhere on here....but there are a couple of other good ones too.

On my way to work I just noticed an 80 psi oil pressure while driving. However, it drops to around 40 psi at idle. It wouldn't be the sending unit,would it? Does a bad one fluctuate like that or does failure indicate a peg at 0 or 80?

I'll fiddle around with it when I get home. I think I might have used a "high mileage" 1030 oil, heard that can create a higher pressure.

2000 XJ Classic
90k miles

Replacing the 4.0L Oil Filter Adapter: http://www.yuccaman.com/jeep/filter.html

rumblebelly said:

On my way to work I just noticed an 80 psi oil pressure while driving. However, it drops to around 40 psi at idle. It wouldn't be the sending unit,would it? Does a bad one fluctuate like that or does failure indicate a peg at 0 or 80?

I'll fiddle around with it when I get home. I think I might have used a "high mileage" 1030 oil, heard that can create a higher pressure.

2000 XJ Classic
90k miles

Click to expand...

At lunch I turned the key on to fire up the gauges without starting the engine. The oil pressure gauge floated to 30+ psi while the engine was off. Turned on the engine and it went from 30 to 80 psi.

i have a 93 4.0 and have the same problem. I have replaced about 10 sending unit last year, for a while it was about every 3 weeks, after every oil change, now i have ran on the broken one for about a month and no real problems have accured... So WTF, will this hurt the head or block? I got tired of messing with it. btw i got my sending units from autozone, cause there only $23 there versus $65 at a dealer.

Aren't the 96s equipped with the 1-qt filter mentioned on Yucca-Man's page? Or is there room for improvement?:guitar:

Using a 91+ oil filter housing it is possible to fit the SAE threaded Motorcraft FL1-A which has a 1 quart capacity.

ChevelleSSLS6 said:

Aren't the 96s equipped with the 1-qt filter mentioned on Yucca-Man's page? Or is there room for improvement?:guitar:

Click to expand...

The 96 (actually the 91+ ) has the horizontal oil filter adapter but comes with a 1/2-quart filter stock. The 1-quart filters listed at the bottom of my page will fit with no modifications needed.

so if i change the 1/2 quart filter it will stop breaking the sending unit. Please tell me so, So i can fix this reaccuring problem

that gurgling noise,could you hear it inside the cab if you lean your head towards the stereo deck?i have a gurgling that sounds when you lean in but you can't hear it on the outside of the car

the sending units like to wiggle themselves out of the connection so you should check it every once in a while.normal pressure is:in the morning 55-75 sounds about right when cold.hot should be about the same WHEN DRIVING.upon the first minute touch of the gas pedal that oil pressure should shoot to 55-75,a little less if you have been driving a while,say 45-1 hr.at a warm idle,between 20-40.my 95 with 167 has 40 at idle while my 89 with 226 has about 25.