I have a 2001 ram 2500 5.9 gas 4x4 one of my trans cooler lines blew off last night I didn't know about it till the truck didn't want to move so I hobbled it to a gas station shut it off and hooked the line back up topped the fluid off and drove it home no problems today I started it up double checked my trans cooler line and fluid all was good drove down the road and the truck just wouldn't move I shut it down opened the hood everything looked good so I started it back up and it took off fine then did the same thing again so I turned it off re started it and it took off fine it moves fine about 20 feet then its like the truck is in park I shut it down start it up and it does the same thing any one have any ideas on what might be going on this problem has me baffled

 

Are you checking the trans oil level in neutral not in park? Oil level can be hard to read on the trans dip stick, make sure you really are filled to the full mark.

 

I checked it in park cold then in neutral hot and both ways it was where it was supposed to be

 

What caused the line to blow off? Could your check valve or trans thermostat have clogged? Sometimes it takes a little time and shifting the lever thru all the gears to get the air out of the trans.

 

I'm not sure what caused the line to blow I just put a new radiator in and I might not of had the line tight enough or could have been worn out threads is there any way to bleed the transmission and get the air out I was also told it could be a clogged filter

 

I'd start with a transmission service- oil drain and install a new filter. When your in there, check the magnet for excessive debris, clean and reinstall. If there's no magnet put one in. There is a dimple in the pan you can put a donut magnet there or a rare earth magnet. either one will work. This helps prolong the life of the filter and inevitably the transmission.
After replacing the oil, you need to run the shifter lever through the gears several times and recheck the oil level before driving. The transmission needs to be at operating temperature when rechecking the oil level.
Aloha

 

Also needs to be in neutral. You don't have to worry about doing anything in particular to get all the air out, that will happen in the normal course of events anyway.