Just drain transmission fluid from hoses, not from transmission itself. Learn how to remove automatic transmission lines to replace a car radiator in this free auto repair video from a master mechanic.
In this segment I'm going to cover disconnecting the automatic transmission lines. We just finished draining the vehicle, I reinserted the petcock and tightened it up so it won't drip while the pan's being removed. I removed the pan of antifreeze so as to not contaminate with the A.T.F. and slid a different pan underneath the vehicle. Now, what I'm going to do is disconnect one line at a time and a tip, if you've got a couple of bolts, there approximately the same size as the lines connecting to the radiator, you can use these for temporary plugs in the lines. I have flexible rubber lines that come up so I can not only put these in and use them for temporary plugs, I can also raise the lines up and get them above the height of the transmission. Just gravity alone will stop the fluid from leaking out. Once we disconnect them we want to drain, we want to drain the fluid out of the radiator itself, the cooler assembly. We don't want to drain the fluid out of the transmission. I'm going to disconnect one line at a time, insert a bolt in it as a plug and we just want to slide them in there and lightly tighten it down. We don't want to clap them on there real hard. We don't want to the grooves in the bolt, the thread in the bolt to cut into the rubber on the inside of the lines. There just a temporary plug. The clamps on this one is original style and its actually a slotted screwdriver, 10mm head on it. I'm just going to loosen those up. Once I've got it lose, I'm going to twist it back and forth to break it free from the fitting and just slide it off. Once disconnected, I'm going to hold it up high so gravity stops it. I'll insert a temporary plug and then lightly tighten it down. Then I'm going to slide up under the plug wires and make the plug wires as a bracket to kind of hold the line up above the height of the transmission and gravity alone will assist me in keeping that from draining any further. In your pan placement, you want to make sure you've got it down below the flash shield because the fluid is going to run down and across the splash shield and then into your pan. After you've got one line removed, go ahead and disconnect the other one. Same procedure, we want to loosen the clamp up real loose and then break the line free by moving it back and forth. If you can't do it with your hands, just lightly grip it with a pair of pliers and just twist it back and forth to break it free from the fitting and then you can slide it off. Just wiggling it back and forth as your applying gentle pressure. You don't want to use an up and down or side to side, just a twisting motion. We don't want to put any stress on that fitting in the transmission. This is especially true when we put the new transmission back in. Once I've got the other one free, I went ahead and inserted a plug in it and tightened it down and I'll just stick it up behind the back side of the cam with other one, kind of hold it up out of the way and let gravity help as well. Please watch our next segment. We'll cover removing the lower radiator hose.