Weekend plan to work on.

 

Personally, I think you're engine and the video posted of the flywheel noise sound completely different. When you drop the oil pan make sure you skim through and look for any metal. I've seen the 4.0 missing a good chunk of piston and still chug along.

 

That Autozone Oil Pressure Sending Unit is wrong for your 2000 XJ.

The original OEM part number was 56028807AA, which has now been superceded by part number 5149064AA.

See this:

http://stores.revolutionparts.com/mo..._str=5149064AA

 

I think its the fly wheel bolts. when I first opened this thread I was going to mention that other thread and video that was posted. mine is making the same noise, I have 250k miles. oil always comes out clean, oil pump is clean, and my oil pressure is always where it should be. I plan on checking my flywheel bolts on my next free weekend. please post your results once you get a chance to try and tighten them

 

I am kind of kicking myself because the pan was just dropped (totally different issue, the pan gasket was leaking) and I had the mechanic do the oil pump also because I figured why not when you are already in there. I kind of trusted that they would investigate the noise while it was down but they did not. He did tell me everything was sparkly clean with no metal or issues. My problem is I care more about my Jeep than the mechanic does but I am not capable of doing much mechanical work. So he likely spent the least amount of time possible to do the job (gasket and oil pump) and didn't take the extra few minutes to investigate the noise. I usually try to be there while the work is being done so I can get in an ask questions but I was not there for this one.

 

Did you try this test to rule one out?

 

Yes sorry thought I established that the noise goes away (or becomes way less noticeable) once the Jeep warms up. When warmed up and driving she purrs like a kitten. I can floor it on the highway and hear nothing out of the ordinary. I can take off when the Jeep is cold and noisy and see if it goes away when driving? But realize I have no noise at idle either once its warmed up.

I have 0w30 Penn oil that I just got from Amazon, going to try and put that in this weekend, it is pretty cold here is it possible this could help?

 

Rod noise cannot be heard at idle unless it is about to throw a rod and it gets louder and LOUDER with RPMs. It gets WORSE when engine is warm. Piston slap subsides when engine warms and goes away when rpm increase without a load (in neutral). Oil weight can have only a slight affect on noise if any at all. On a cold engine it is normal to hear noise for a second or two until oil circulates and in this case a thinner oil will help.

 

So in your opinion I have piston slap (which is less of a concern than a rod knocking)? And we all agree there is no point in trying to fix it, just live with it and be prepared to rebuild at some point?

Uploading a new video now, very interesting, I put phone under jeep and cold started then reved it up to see what noise does. Its almost as if the noise is independent from the engine, the reving engine seems to mask the sound but not really have any effect on it. My ears may be playing tricks on me but its almost as if it isnt even coming from the engine. I will post as soon as its up, opinions are very appreciated. Edit after listening a couple of times the knock does seem to speed up with the engine, but its very hard to tell.

Here is video:

 

1. Does the noise change or go away if you pull one spark plug wire at a time, then listen?

2. Get a helper and a mechanic's stethoscope and try to get a better idea of where the noise is originating. Check the transmission too.

 

I have coil pack, don't think I can do that trick?

 

Pull the wire at the spark plug, engine off?

 

That's getting dangerously close to over my head maybe I will mess with it this weekend.

 

Unplug the injector....same results

 

Main thing is to take each cylinder offline in an effort to try to isolate the noise.

I'm old school. Used to the separate coil, distributor, wires like on my '87 and '92.