Automatic transmission rattle in neutral when hot

I have a 2013 double cab 4x4 TRD off road with the v6 and automatic trans 9,000 miles. Once the truck is hot I hear a rattle that sounds like I have marbles bouncing around in the transmission but only in neutral. I used a stethoscope on everything under the truck and it sounds like it is coming from the transmission. Once it is in gear it goes away. I have heard of this happening in manual transmissions but never in an automatic. It's loud enough that I can hear it inside the cab. Anyone else have this issue? Is it normal? I have searched around here for a while and have not found anything that matches this situation. Any help is appreciated!

 

not normal. V6 auto on my 2012 w 25,000 miles, zero noise when not in gear. except for the noisy motor...

 

Okay, thanks for the reply. Sounds like I need to go back to the dealership.

 

Lets break this down a little more . When you have the trans in neutral , what gear is the transfer case in ?
When you idle in neutral , there is some drag on the forward clutch causing the output shaft of the transmission to slowly spin which would cause the transfer case input shaft to slowly turn providing the transfer case is in neutral as well .
My 4x4 didnt come with a neutral option for the transfer case , but not sure if yours did ?
Very strange that an automatic could sound like marbles as most use torrington thrust bearings rather than typical roller bearings .
In my opinion , i would suspect the noise is caused by something other than the auto and is being transfered into the transmission .
Now if this is was a Ford product i could truly understand the issue as I have seen missing thrust bearings from the factory . End play on the A750E is set at approx 20 to 30 thousandths of an inch making it impossible for missing parts such as bearings or the possibiltiy of misassembly unless its a Ford hehe .
For the benefit of doubt , use a large pry bar while in neutral and pry the transmission from one side to another listening for a change in pitch .
Agree with the above poster to have it inspected by the dealer for sure

 

I say have them check the torque converter bolts,
had an old buick that made that rattling noise in nuetral an it was the bolts that
go thru the flex plate to the t/c

 

Thanks for the ideas, I will check it out and let you know what I end up finding.

 

Just want to update everyone on this... The noise would not happen if it was less than 50 degrees out. So for most of the winter it did not happen. Last week it was 55 out and it was making the noise so I decided to drive it straight to the dealer and asked that a tech ride with me. We went on a ride and he heard it too. We went back to the shop for him to investigate further. After and hour or so they called me back and said it was a bad bearing at the back of the transmission (I assume the output shaft) and they ordered a new transmission and torque converter. Just got it back Friday and so far I have not heard the sound come back.