Listen to the video in my post above - this is not the liner tap

 

I have considered the slipping liner but have discounted it for a few reasons, the sound isn’t right and it’s pretty quiet up top. I do have a “180” degree t-stat in but I don’t think it’s actually opening at 180, but that’s another thread (literally).

 

I listened to it, you have a mixture of sounds - deep booming exhaust notes, some ticking, some normal accessory noise, some small exhaust leaks. But given the oil pressure there is only a small chance the ticking is anything top end. The most common issue is slipping liners, and the fact it only does it hot is a dead giveaway.

 

My understanding is that the sleeves are loose, you can really hear them smacking the head, and that the sound is pretty distinctive. This is the noise that I've always associated with slipped liners:
The best way I can describe this is that it sounds like a diesel engine, and I've never heard slipped sleeves described that way. From what I've read, it sounds like 4.0s are less susceptible than the 4.6s. I think both @greisinb and I have 180F thermostats and coolant temps around 190F, so it's not a matter of the engine running at 220 or anything, and we're both running 15W-40 Rotella. The only thing that seems to line up with it being a liner problem is that the noise appears once the engine is hot.

I appreciate your replies and I don't want to come across as though I'm telling you that you're wrong - you know more about this than me - I'm just trying to understand how you got to that conclusion. I also posted on another board and the consensus was that it was likely not slipped liners.

 

If you really want to determine if it is slipping liners notice the exact temperature when it starts. Most of the time it is between 140-190 degrees. Bypass the thermostat and see if it goes away. If it does, slipping liners.

 

Update, Part 1:

I did a leak test comprising of using my shop vac to blow up the tail pipe and spraying a soapy water solution along the exhaust. I found a leak on the driver side cat and in the connection between the exhaust manifold and down pipe (see pics below). I’m using an exhaust repair paste on the cat, it’s curing now. For the gasket leak, I tried to tighten the bolts but they were pretty tight already, might be rusted stuck. I also hit it with an impact gun, we will see what the results are tomorrow after the cure takes hold.

 

Exhaust manifold to pipe gaskets are stupid cheap at Advance, you may want to throw a set in there. Yes the nuts and bolts are probably rusted. 50/50 chance they will snap off unless you are super careful. Spray them from above with Kroil - use a hand ratchet to loosen them - not an impact. If they get tight in a spot work them back and forth - do not just torque it, they will snap very easy. Good luck.

 

Thanks, I'll look in to that- I was very gentile with the impact as I was afraid of snapping them off and didn't want to overdo it.

 

Any update?

 

The paste for the cat seems to have taken hold, but it looks like I’ll be replacing the down pipe gasket to make it appreciably quiet.