Grinding Noise???

[willywonkaisrsh]

So after driving my 2004 Limited V6 4wd 4runner with 80k miles an hour down the road to visit my inlaws I pulled in a parking lot and heard this horrible grinding/rattling noise. I would continue to do it while still in gear or if moving slowely. As soon as I put it in park it would stop. I left it alone and came back 10 minutes later and it was still doing it, but only off and on. The car drive fine and nothing seems to be wrong. I even put it in 4wd and drove it a little and it was fine. I let the car sit again for about 30 minutes and drove it 15 minutes down the road and it only made the noise for a split second while taking off. When we got to our destination I couldnt reproduce the sound. I drove it in circles, braked a bunch, changed gears and nothing, until I put it in reverse and started to back up. So now the sound only happens when backing up and it is still only off and on. At first I thought it was the heat shield but it sounds worse than that. As a side note, a week ago I greased the driveshaft and propeller shaft. So does anyone have any ideas what it could be?

 

[03blkrunner]

Wow, this is pretty much exactly what just happened to me. Greased my prop shafts (drive shafts to everyone but Toyota), drove 430 miles and then started noticing a noise. It was consistent with speed but when I looked under the truck I didn't see anything. I figured it was something rubbing on a rotor or since I just greased everything that something else had gone horribly wrong. Yesterday I got under there and took a better look and it was a heat shield. The shield over the muffler had completely come loose from the truck and was resting on top of the muffler but one edge was rubbing on the drive shaft. It was hard to see because it looked pretty normal until I got under the truck.

Hopefully that helps because it was a much smaller problem than I was beginning to worry it was. Of course now I'm upset that the shield has corroded off, I guess the old girl is starting to show her age.