Last week I started noticing a rhythmic tick/ knock coming from the engine and hoping it was just a noisy valve, I did a sea foam treatment today but while I was driving the jeep after burning off the sea foam, I heard a weird sound from the motor (not sure how to describe it) and then my knock got louder and added a new sound like something is rattling now too. I'm not sure if it's a piston skirt as it doesn't seem quite as loud as most of the videos of those but I just can't tell. If no one has any better ideas, I'll be double checking the flex plate then dropping the oil pan tomorrow to check. Here's the noise... https://youtu.be/v_G5RhWELN0

 

Take a long screw driver and put it up to your ear on the handle side and but the other side on valve cover. Move around until noise is loudest. Also do the same on the oil pan. This will help pin point if its valve/rocker noise or in the lower end with out breaking into motor. Hard to hear in video but sounds like rod bearing but hard to say. If you have a stethoscope that works too for listing

 

I tried that this morning and I was having a hard time pin pointing it, it sounds like it's coming from the mid section of the motor but I can't tell if it's originating from the top of the motor or down below. I am fairly convinced it is a piston skirt now though as I've watched a lot of videos with a sound very similar to my own.

 

I guess that'd do it.

 

what are we looking at there? chunks of piston skirts?

 

I had the same thing happen on my 98 wrangler. I would not drive it till you get the piston replaced. In order to change it you have to pull the head and seeing that you have a 2000 XJ you should probably check the head for any cracks wile it is off. The best thing to do is to replace the piston and rod as one unit. Also since you have to get new rings and bearings for one piston you should probably change all of the rings and all of the rod bearings wile you are in there. It is not an impossible job and can be done without pulling the motor. Once you have all the parts lined up it can be done over a very busy weekend. Get your self a good torque wrench if you don't have one already, and a good 4.0 engine rebuilding book for the torque specs and clearances that need to be checked.

 

Been there, done that. Lost piston skirt #6 on my XJ with 225k miles. Pulled the head. replaced all the pistons and rings. Also replaced connecting rod bearings and oil pump. Hardest part was getting the oil pan off. I used dental floss to tie the new oil pan gasket in place while I fit it in and got the bolts started.

 

Yea I'm not sure yet which piston gave up the ghost, but from the looks of it that piston is pretty much gone. I had a Motor from my old 98 XJ that I rolled so I'm in the middle of swapping that over right now. I figure I might as well just throw the motor with 150,000 miles in there rather than mess with a motor that has 256,000 haha.