New guy here. Lurked for awhile but now I have a mystery that I need some help with. Figured I'd see if someone else has come across this. I searched and at least from what I could find, nothing quite similar to mine. If someone knows a thread, shoot me that way.


Bought an 07 LR3 HSE last year for a good price. Its got a few mystery sounds that I have yet to fix. This one in particular worries me the most however....


There is a random, light, metallic chatter. It seems to do it more during colder months versus warmer. Although it'll do it randomly while driving too. Doesn't seem to change speed, at least that I've noticed. Have to have the windows down and radio off to hear it. Happens in park at idle mainly but I noticed today while checking O2 sensor voltage. I could get it to do it faintly around 2500-3000 RPM. Still wasn't happening every time. So a bit hard to trace. Sounds like it's coming from underneath. Almost like the trans or bellhousing area. But it could just be echoing off the ground and tricking me.


I crawled around and checked most the heat shields and they seem to be fine. Looked for loose hardware and all that stuff. Though I would think I could get it to be more consistent if it was something like that. I'll post a video from December when it did it long enough for me to pull out the phone and record. The only error code I currently have is P0420. Which is intermittent, and hopefully gone since I changed a bunch of stuff this last weekend.


Possible timing chain issue? Has 120K on it. Drives normal, at least most the time. I fully serviced it recently. Let me know what you think. Thanks for the help.

 

Timing chain issues are more inherent to the LR4 than the LR3. That said, my Timing Gear is "out of round" and that results in a 2.7 second clatter at cold start, but no other time. I can literally start it cold, count to 3 and it's gone before I get there. At that point, I can turn off the engine, and start it up again and....no clatter. I'd have to wait about an hour with engine off to re-start and hear it.

....so that's not it.

Edit: I just watched the clip. That's not the timing chain from what I can tell.

 

Which I agree. I figured the chain would be more noisy at start up. Not as random as this. I found I can get it to be a little more consistent at warm up if I feather the throttle at 2900-3100. Even then it's faint. I had my brother finally help. Popped the hood and gave it a go. He couldn't hear anything under the hood, or not as well over the fan, but I could from the driver seat. Then he got underneath and I did it again. First thing he said "sounds like it's coming from the cat". Of course those are near the front of the trans.

At this point I'm considering pulling the bank 1 cat since I have a code and seeing if I'm lucky enough that something falls out or using an inspection cam to get down to the honeycomb. Not likely if it's more internal. It doesn't have the typical rock in the exhaust sound that I'd expect. And it's not happening at all revs. Just around idle and ~3000. Plus the code is more recent. It's been rattling like this since I bought it. Code wasn't until this month. Not sure if it's related. But I'm at a loss.

 

Sounds a lot like a 10mm wrench stuck at the transmission shifter linkage and thus rattling on the exhaust.