Bad trans cooler lines

Working on my brother's '97 F150 standard cab w/4.6L VIN 6 and 4R70W (I believe) 4spd automatic. We live in Michigan and the trans cooler lines are corroded to the point of leaking due to exposure to salt used on the roads in the winter. I briefly looked at the lines where they are connected to the transmission and it appears to be extremely difficult to get to these connections because there is a heat shield around the right cat that is in the way. If anyone has some experience with changing out these lines I would be grateful for your input. Thanks. Rob

The trans oil cooler line connections at the transmission are a bear to get at because of the lack of clearance, but I had some success that I will share.

Remove the right front wheel.

Remove the plastic inner fender liner which is held in place by a few push in
retainer clips (christmas trees) and 4 screws (7/23 socket) along the fender lip.

With the liner removed, remove the front bolt (13mm socket) in the right side inner heat shield for the catalytic converter.

Underneath the vehicle, remove the middle bolt (13mm socket) attaching the heat shield to the trans tail piece support.

Remove the bolt (10mm socket) which attaches a bracket to the inside of the frame that the rear of the heat shield is attached to. There is a bolt that is threaded down from the top of the heat shield and into this bracket, but insufficient clearance to back it out.

Now that the heat shield is loose, it can be maneuvered around a bit to gain some clearance, but you will still have to bend it to be able to get room to get a hand up to the connection area.

I used a 5/8" open end wrench to loosen both lines because I did not have access to a flare nut wrench (I have a metric set). One connection came off easily while the other one twisted the line. Fortunately it was the lower of the two lines that gave me the trouble and I was able to use a hacksaw to cut the line. The flare nut came off with the transmission stub (MPT to FIP double flare connection adapter) still attached. The flats on the adapter require a 19mm wrench to hold while threading out the 5/8" flare nut, but there is not enough room to use two hands for this job. I think the job would be much easier if one had access to a set of flex head ratcheting flare nut wrenches. Not sure if one could use two wrenches at the same time in this limited clearance space.

The two connections at the radiator are pretty straight forward, although there is a clearance issue concerning the lower connection. The FIP adapter on the radiator is 22mm and is nearly impossible to get a wrench on in order to hold it in place while threading out the flare nut. I was able to use an adjustable wrench for the upper adapter, but not the lower. Unless you have a 22mm open end wrench, which I did not, you'll probably wind up having to cut the line and thread both the flare nut and adapter out as one (should yours be frozen like mine was). If this is the case, you will need to drain the radiator prior to removing so you don't lose coolant to the ground.

Hope this helps someone in the future. I'd post photos some photos, but I'm not sure how to go about doing so.

Well, this might be a late reply, but for the future, I used to live in Maine, with my F-150, before I got tired of the rust.

Though dangerous to some extent, I rhino lined a lot of my metal piping, minus exhaust, and major engine parts. But, It stopped quite a bit of rust.

Keep in mind, it's heavy once it's applied, and leave a sliver of metal showing, just incase you have to make an emergency cut.