When towing in OD with my 07 E350 PSD I get 60mph at approx. 2000 rpms. Sometimes, when going up a hill it shifts down to 3rd, I assume, and the rpms go up to approx. 3000. Other times, the transmission doesn't distinctly shift, but the rpms hover in the 2500 rpm range.

My question is: When the transmission shifts between OD and 3rd, back and forth, is that considered "hunting", or is "hunting" when the trans doesn't distinctly shift, but hovers between OD and 3rd?

 

Hunting is when the tranny "CONTINUALLY" searches for the 'right' gear it wants. If it just does it going up a hill, it's working actually the way it's supposed to.

 

I would also consider the od going from locked to unlocked as hunting and potentially building heat.

 

Sounds like the torque converter is unlocking, causing the RPM to increase. This can also build up heat if it's cycling over a long period of time.

Steve