What's dat funky sound?

[4x4Dreamer]

My truck has been running really well for some time now, no compaints. I do have this rattle I can track down. I know that it's supposed to have some rattle, but mine has a really mattalic sounding rattle that will sound for a few seconds, then everything will smooth out for a second or two, then it comes back. As far as I can tell it's only at idle. I can't find anythign loose around the engine.

My concern is that it's something IN the engine. It used to have a lot more time in between it's doing this, but it's getting more and more frequent. I just hope I don't have lifter or other issues in my near future.

Does anyone have any ideas what it might be, or at least where I should start looking?

Any info is greatly appreciated.

[DmaxMaverick]

Check your harmonic balancer, for starters. You could be getting some air in the fuel, somewhere. Does the engine speed change with the noise?

[TimK]

Since we are all taking an educated guess, here's mine.

It sounds like to me that you have a bracket that has cracked or broken and as the fastner is working itself loose or the surface is wearing from vibration it's rattling.

I suggest inspecting the brackets on the alternator, power steering pump or AC and see if a bolt has worked loose or a bracket has cracked.

TimK

[Trond Stordal]

I was experiencing a metallic rattle, specially when idle. There is a metal rod bolted to the transfercase, it makes a bend upward and is supposed to be bolted to the engineblock, passengerside. Mine was not and made a nice rattle.