I am about to change the Mercon V fluid in my '03 F4X 4X4 with the 4R70W trans and 5.4 L engine and need help. It was definitely easier in my '97 with a TC plug! I have read every post I could find about using the cooler lines. I can not get to the return line at the trans due to the Cats and shields without major effort. The radiator is also out of the question due to the quick connect fittings, air cleaner and other goodies. The return line runs from the radiator to a 2ndary OEM cooler mounted in front of the radiator on the passenger side. There is also another smaller cooler on the drivers side (oil cooler?). It looks like the 2ndary cooler would be the easiest connection to break but the connection looks like a flare fitting and feels like it is spring loaded as it moves slightly but shows no sign of leakage. Can anyone tell me if this line is safe to disconnect and which side should be used? All lines are hard with crimped on flex hoses that can not be disconnected except at the trans, radiator or cooler.

Thanks in advance...

 

Is paying a shop the $100 to use a fluid replacement machine out of the question?

 

YES... I know of several friends who used a shop or dealer and in all cases it caused more harm than good.

 

It does the same thing you are trying to do - a complete fluid replacement.

 

The small cooler on the left side is a power steering cooler. If you think getting to the two cooler lines on the side of the tranny is impossible because stuff is in your way then maybe this is too much of a task for you. Not trying to be a jerk, sincerely, just throwing out some ideas.

Moving on though, yes, you can disconnect a line at the tranny cooler. Disconnect the line that runs from the radiator to the cooler. Take it off at the cooler. The fluid will pump out of this line. If you disconnect the other side, it will pump out of the cooler and you wont have any control over where it goes other than straight down.

 

Completed it this weekend and was easy using the cooler line.
Thanks...