Hi everyone,

I know this has been discussed before in previous threads and most people seem to be talking about torque converter bolts.
After checking my bolts they all seem to be tight. I also did not see any kind of cracks on the flex plate.

My question: is the noise sounding like a « torque converter bolts » or would it be something else or I have also seen people say that it is normal noise for jeeps 4.0?

here’s the video of the sound attached:

 

sounds like a leaking exhaust or cracked manifold

XJs are noisy, but that is much louder than mine with 2.5" exhaust

 

ok I will check on that. it really only does it when it’s cold at idle

 

Cold at idle knock....and that's a knock.
try this.
When it's cold and knocking disconnect one plug at a time and see if the knock changes when you have a specific cylinder killed. If it does.... piston/wrist pin maybe

This would be harder with late coil rail engine, would need to disconnect injectors
... but since the MY of the vehicle is secret...

 

engine stethoscope or metal rod to help identify area of knocking

have engine oil analyzed, cost about $40, if there is high level of bearing metals in the results you will have a pretty definite answer

Could also be piston slap

A mate of mine was a mechanic for over 60yrs, including over 10 years working for an engine rebuild company, when there was many XJ about

He owned many XJ and told me that they have only a couple of weakness, one being pistons can become damaged, and he said one type of bearing was always worn, as it was relatively smaller than the others. It was a rod bearing, I think the lower

 

Unfortunately I can’t post more videos but I have found that the noise seems to be louder when my oil pressure is high (60) (usually when cold or when accelerating) I do not hear it anymore when the pressure comes back down to « normal » (40) (when idling after being on the highways)

This would be telling me that it is more engine related.
just bringing more info to this.

 

If you done any work to your Jeep, then take a look at the exhaust pipe. Just abovethe transmission cross member period there's a very lowclearance and it is a common problem for them to rattle against. The cross member, especially after you put it in drive. But your noise sounds more like my new exhaust system, which is stock. Just some thoughts thrown out there.