By Rebecca rover on Saturday, June 16, 2001 - 06:37 pm: Edit

How do you tell when your cats go bad? Does it rattle when idle ing or just when the truck is moving?

I am having a rubbing/marble rolling around under my car noises...It only occurs when moving, not while standing still. again, only when moving. I can stand still and give it alot of gas, no noise.

I went out just now to re-asses the problem, drove around the block and it was gone.

anyone have any ideas?

By Mike B. on Saturday, June 16, 2001 - 10:29 pm: Edit

What year Discovery are we talking about? Has the vehicle been off-road? This could be the cats or the muffler.

My muffler is pretty dinged up and it rattles on occasion, but only at idle speed. I have heard that the noise is caused by one of the internal baffles coming loose and rattling around. The home-grown fix is to try to isolate the loose chamber. Then take a rubber mallot and bend the muffler up at the source of the rattle. This is only a temporary fix and eventually the muffler will have to be replaced. I haven't taken a hammer to mine since it never seems to rattle when I have my hammer ready.

I suspect that you might have the same problem. Don't worry, it will start to rattle at idle soon enough.

Lots of Luck,
Mike B.

By Will on Sunday, June 17, 2001 - 10:22 am: Edit

Could be the heat shield....Mine came loose and did the same thing.