Popcorn sound coming from under shifter

Popcorn sound when driving. Just started. Sounds like an air popper. Still happens when coasting in neutral, as well as in drive. Any suggestions? Thanks in advance.

 

Sorry man...got nothing else.
Curious though.

 

I discovered it only happens in 4wd. So I’m thinking it’s a problem with the transfer case. That make sense?

 

Grease the front driveshaft U joints and see if the noise changes.

 

you just cant make this stuff up

https://nationaldaycalendar.com/national-popcorn-day-january-19/

 

U joints typically make a click, clack, click, clack, or a squeak, squawk, squeak, squawk sound when you are driving real slow. The driveshaft turns almost 4 times faster than the wheels and as the U joint bends, it usually makes noise every 180 degrees of rotation. The result is a noise with a frequency almost 8 times faster than the tire rotation.

 

Crawl under truck and remove the nylon tie-wrap(s) your prankster buddy put on the front driveshaft

 

Just throwing darts here but perhaps the air relief valve on either the transmission or transfer case is burping due to the valve partially clogged, or too much gear oil and it is expanding. ToyMoCo has a newish bulletin out specifically focusing in these and says to replace them whenever the transmission/transfer is pulled. They must have had a number of reported problems.

 

Thanks everyone. Bought a grease gun, crawled under in this lovely 10 degree weather. Greased the u joints. Problem solved! Thanks muddinfun!

 

you have damaged them already with lack of grease
grease will only help for a while