Z3r0x7

As the title says I have a 00 with a check gauges light that comes on when the engine warms up.

I have replaced the sending unit. While I was replacing the sending unit I had someone start the motor and rev it to push a bunch of oil out the elbow for the sending unit.

When it gets down to 0, I dont hear any knocking or odd noises.

I'm using t5 10w30, should I use something heavier?

Any ideas would be awesome

Video below
https://youtu.be/NwAgOUGh0ms

X1997J

Mine was doing the same thing, I ended up having to replace the wire harness that plugs into the oil switch.

PatHenry

I would verify the oil pressure with a manual gauge. You can get one at harbor freight for under $20 just to be sure.

Beyond that, I'd try cleaning up the sender connector really well and as mentioned, possibly replace it.

GreaseMonkey17

Z3r0x7

Thanks guys sounds good, I'll get one tomorrow.

Does the engine sound fine from what you could hear?

Ralph77

If you are going to do that you might want to do what I did. I used some brass fittings so I could hook up a mechanical gauge easier anytime I wanted.
I own an '00 and had been meaning to throw a mechanical gauge on it for the longest time. Just to see. Am not having any problems.
So I figured I would rig this up and also lets me see how the mechanical gauge reading corresponds with the cluster gauge reading.
22 lbs at a hot idle and the the mechanical gauge and cluster gauge are in sync for the most part.
If you want the part numbers for exactly what I used let me know.

Z3r0x7

thats a great idea!

This may be a dumb question but did you happen to listen to the motor in that video? does that sound like a healthy motor?

Ralph77

I don't usually check out the videos. My hearing sucks and my eyesight is not much better. Plus to be frank most of the times the video sucks anyway.
But since you asked I checked out yours. Wish you had filmed longer so I could hear the engine from the engine compartment.
Nothing jumped out at me but.....

Don't want to get you all worried but you own an '00. So Google 0331 head. Time to educate yourself on them just in case.
This is a more common occurrence in '00's and '01's.
Brief summary is they like to crack. Basically poor manufacturing.
One of the symptoms is little or no oil pressure at a hot idle. You appear to have this problem.
Another is milkshake oil. Thinking you would have said something so you don't have this.
Another is an unexplained loss of coolant. Are you?
So I have had no first hand experience with a cracked 0331 head.
Just what I have read on the internet. Also let me say that I wonder if this problem is played up a little.
Like reviews on a product. Less people will post a good review but have a problem with the product?
Look out. They need to vent IMO.
But in your video I kinda thought that when you revved it up that the oil pressure gauge would have jumped higher
when dealing with this issue. I mean like around 40. But again no first hand experience
Maybe you did not rev it up enough and for long enough.
Point being maybe it is gauge related.
As suggested put the mechanical gauge on there, get her nice and hot, get a reading at a hot idle, and report back.
Thinking don't take the time to do that set up I did at the moment. Concentrate on the problem at hand.
Of course I am big on the "Well while we are here maybe we should..." thing so.......

PatHenry

I think it's not really a question of it being played up (in that, the actual occurrences are much fewer than the "hype"), I think it's a question of the severity of the issue.

We all know and agree that the OEM 0331 head found on 00 and 01 XJ's (as well as other Jeep models) is constructed in such a way that it is susceptible to cracking. We all know and agree that there have been such a number of cases that it's considered at the very least a "known" if not fully "common" point of failure.
The reason why it's so vital and important for owners to be aware and educated is that there is a world of difference between an -early- diagnosis vs. a -late- diagnosis. If you can detect and correct a cracked head early, it is a relatively simple replacement of the cylinder head. A job that is well within the capabilities of most amateur wrenches and doesn't require a lot of expensive specialized equipment. If you ignore the signs of a failure and just keep topping off the coolant and turning the radio up, it doesn't take long for the antifreeze in the oil to ruin the rest of engine and then you're dealing with major operations like engine rebuilds or full motor swaps.

Just my thoughts on the matter. For my part, I put over 300k on an 0331 head engine (being I was the original owner, literally -I- put 300k on it) without a failure and as far as I know that engine still runs great today. At the same time you can look at the posts over the years on this forum and see plenty of instances where folks were less lucky than I was.

kbeam418

I watched the video; it sounds like a healthy and happy 4.0 gauge might be bad, sending unit could be bad, who knows but I wouldn't worry about it. If you had zero oil pressure the engine wouldn't even run and if it was too low you would get some rattling and knocking.

Ralph77

Makes perfect sense. I only have a 167K on mine. Also I am the third owner. I do know that it is a 0331 head from when I did the valve cover gasket. What I don't know is if it has been replaced at any point. I think all is well.
Last year to get a handle on where the condition of my engine might be at I started running some tests. So far have done a cooling system pressure test, compression test, block test, and threw the mechanical oil gauge on her. IMO so far so good. Hopefully this year I will get to the leak down test.
But just in case in my travels I was able to pick up a couple TUPY heads. Paid $50 for one and got the other for free. Could be OK as is, maybe rebuild-able if not, or could be door stops. Worry about it if and when the time comes.
Which is why I am always keeping an eye on my engine. I pull the plugs every year so I can give them a quick look. Just cause I bought a compression tester thinking going to run a compression test every year too.
I rigged up the fittings on the oil pressure sensor so I could slap a mechanical gauge on there anytime I want will minimal effort. I dump my anti-freeze every other year and since I bought the block tester figure do that just before I do every other year too.
As you pointed out I figure it is all about maintenance and catching problems in the early stages.

Z3r0x7

So I ended up putting on a oil pressure gauge and testing hot idle around 500 rpm and getting around 13-14 PSI ( I do have some MMO in there atm)
Does this sound to spec? Should I put heavier oil in?

Thanks guys!

Ralph77

From what I have read that is acceptable pressure. At the lower end of the scale but still OK.
So now to figure out why your gauge is doing what it is doing.
Who did you buy the gauge from?

Z3r0x7

Oreilly's

I'm going to try and replace the connecter aswell

Ralph77

Could just be bad out of the box. Many guys will say to only buy Mopar parts when it comes to certain sensors. I went Napa. The Echlin line one. At least 3 years now and all is well.