Lower motor rattle

[dandruka]

I have an 04 with about 90k. It's always had 10w40 synthetic oil changes, 5w40 in winter, runs great.

I've tried searching on here for answers but can't really find anything that helps. So here is what I think is a problem.

When I start my disco after cooking down, it hums like a kitten. After a 30 min trip or so, however, a sound from the lower engine/sump sounds like a metalic rattle; the sound a bolt or nut would make if it was floating around down there. Goes away when engine is rev'ed.

From experience, I thought it might be the cats, but they sound fine. I get a stethoscope and it's coming from inside the pan. I droped the pan and no parts thank goodness and no scrapings.

Could it be bearings anyway? Valves or rods? I know sound can travel in these motors. It not a horrible noise but it's not something my other rovers have done.

If any one might have a idea, that would be awesome. I could also take a recording if the noise if it helps. Thanks

[Gremlin]

I'd first say that the weld probalbly broke on one of the cat heat shields - but u ruled that out. How about the bolts where the exhaust manifold joins to the down pipes they might be loose. that be my inital guesses

[dandruka]

Not the exhaust. That was my first thought too. I wish it was the cat trust me. I have no noise coming from the cats.

I hate to bother the forum with what may seem like a silly problem. I usually am able to fix or solve most of my issues by using common sence or searching the forum. I'm stumped. I wish I had the time and miney to tear into it but it's kind tough right now. So any help would be much appreciated.