HOW TO? Rusted/bonded brake line fittings

Hi, doing a brake overhaul with the PowerStop Z3 line. I wanted to replace the pictured flex hose runs with the

Power Stop BH00130 Stainless Steel Brake Hose Kit- Front & Rear

PowerStop stainless steel brake hose kit. I'm encountering the typical rusted connections between rigid and soft lines. PB fluid was not successful - I am noticing line twist in the rigid line so I stopped. I've read that MAPP gas works well. Does anyone have suggestions, lessons learned, definitely don't try this, kind of guidance they could offer up? I'm not opposed to replacing that one short one segment of rigid line that goes up above the wheel well - but I know how this can go as you keep working your way up the line trying to break a connection free...

 

Torch will be your friend as you said. Are you using a flare wrench or a regular wrench on the fittings? A flare wrench will be less likely to round out the fittings. Or cut the line and get a six point socket on the stubborn fitting.

 

Flare wrench. I've no problem locking into the nut, it just won't break at all. My problem is that each fitting above and below is rusted too. So, I'm concerned that I'll end up snapping shit all the way up to the master cylinder.

 

Everyone has their favorite rust penetrant, I've had the best luck with AeroKroil. Try soaking repeatedly for several days, The top in addition to the threads so it won't twist the line. Use a quality brake line wrench and see if you have any luck. If not, it won't hurt to try some heat. If that doesn't do it, it looks like there is enough slack in the hard line that you could cut it flush with the top of the fitting, slide a new fitting on and reflare the line. Then bend the line down slightly to it reaches. Good luck with it!
A tip, I've lived in the Northeast my whole life and have encountered this often enough that, not only do I keep the underside of my Tundra sprayed with NH Oil (like Fluid Film) but I smear grease on all the metal brake connections on the underside of the vehicle before they rust. I can clean the grease off of any of them and they will look like new.

 

Gotcha. Maybe try taking the clip out that holds the rubber hose and put some vice grips on the rubber hose and twist from there?

 

What's ironic (and a real pisser) is that I literally crawl underneath mine in the winter and spray the shit out of it on warmer winter days. In my driveway, so I'm not cleaning it off and then immediately driving on wet salty roads again. It's not until recently that I started scrutinizing the truck for troublesome rust and I felt like I had wasted all that effort every winter. I am doing the woolwax treatment this year.

I plan to take a similar approach to all my replacement work as you mentioned, with the grease.

 

You'll need repeated PB blaster application, wire brush, and heat to cure your rust woes.