I have a 2002 F-250 XLT CC 4WD 5.4L and I sprung a leak on the driver side fixed brake line. These lines are original and are 1/4" in diameter. Ford has 2 pipes (brake lines) that make up the run from the ABS booster in the front driver side of the engine bay, snaking it's way along the frame rails to the rear. There is a union that connects the 2 pipes just under the master cylinder and where the frame jogs upward. So, I get replacement straight 1/4" pipe, some pressure unions (rated 5000 psi) from Grainger and begin the work. I cut the bad pipe just under the rear door (easily accessible with pipe cutter) and cut FORWARD of the Ford Factory union that is connecting these 2 pipes.. I bend my replacement pipe and get ready to connect the new unions at both cut points. PROBLEM!! The union does not slide over the forward pipe and yet it "supposed" to be 1/4" diameter. Ford, used 1/4" and 3/16" pipe for all fixed lines. I replaced the rear 3/16" pipe and flex hoses on the rear. I can't fathom that Ford used a pipe slightly larger than 1/4". At O'Reilly's, their digital caliper measured 6.54 on the front pipe piece and 6.42 on the 1/4" cut pipe that came from the truck.
Has anyone ever done a fixed brake line replacement and run into this? Two solutions: Order just the "intermediate" pipe that will run from the ABS Booster to the rear. It's a 2 pipe kit, flared and ready to go or remove the front pipe, have NAPA flare the "repair" end and still be able to use 1 of the Brake Line Unions at the back end of this pipe. Your thoughts...

 

Ford brake lines have a plastic coating on them. That's why I suspect you're having the issue with the union fitting. I just finished replacing my lines on my 2001 cclb. I ran one single 1/4 " from the abs module to the rear hose drop. Just bent up the front 3 feet or so using the old line as a reference on the bench, uncoiled the rest and snaked it in from the front. Lots of fun, yes!