On a trip to Fl. I developed an engine noise that I can only describe to be like a throwout bearing going bad. It is a rattling sound when I coast into a rest area or slow down at hiway speeds. It only happens when the truck is at oper. temps. It could be described as a bunch of loose metal ***** being tossed around inside the motor. It always happens when towing but solo it is harder to get it to make the noise, I'm guessing the extra load helps. When I back off the throttle at 60-65 mph you can hear the noise but it is even louder when you are coasting into a rest area, and I can make it happen again by raising the rpm up to about 1800. If I hold it at 1800 it will continue to make the rattling noise. My problem is driving without the RV, I can't get it to make the noise so I can take it to the dealer to have them diagnose the problem. I would like to have some idea what would be making this happen. The truck runs great no loss of power, no overheating, no signs of anything wrong, except this dang noise. Any ideas? Anything I can take to the dealer because they won't fix it if they can't hear the problem.

 

I've seen this before, as you know noise can travel through the drive line especially under load. the first thing I would check is the center bearing of the drive shaft. the second would be the flex plale in the bell housing. to check the flex plate, powerbrake the truck in drive and reverse, if you hear the noise, you found your problem. good luck.