Loosen a rusty brake fitting nut

Does anyone have a sure way to loosen a rusty brake line nut on a brake hose?

I've sprayed/soaked it overnight with weasel whiz and now have PB Blaster on it. I'm using fitting wrenches, not just open end, but I can feel the wrench starting to slip. I could try vise grips, but I hate to chew up the nut if there is a better way.

I can let it soak longer. I wondered about applying a little heat, but brake fluid boils at about 300 deg. F,so I'm not sure that will help much, after flushing the penetrants off.

Any suggestions? Thanks

Lynn, Sorry to hear you are having such trouble, but I think it has been tightened so much that the connection on the bubble has flared and you will destroy the threads on the way out, even if you get it come loose. I hope it's just a rear wheel and not the front. The brake wrench should capture the nut, and vise grips will just crunch the fitting, sounds like a replacement.

Good Luck, Wayne

I have had good luck with heat - I heat it up, throw water on it to "jolt" it, heat it up again an touch a candle to the thread - wax wicks into the threads and then try it.

Someone told me heating it could blow the hose. I guess I could leave the bleeder screw open to relieve pressure. ??

Or perhaps disconnect at the other end since you will have to rebleed regardless.

Even with the bleeder open it can blow a hose. I used to do a lot of Chrysler minivan front hoses. always needed to heat the nut to get it out of the block on the end of the hose. I knew it was hot enough when the hose blew off the block. (POW!!)
Are you replacing the line or the hose? If it's the hose, who cares if it blows? Just make sure you're wearing eye protection. or beat it to the punch and clip it off before you heat it up.
If you're replacing the line, clip the line just above the nut, and put a socket or the closed end of the wrench over the nut.
another trick I've had to use before is to take the hose end loose from its bracket and spin it off the end of the line. that's only if the nut is seized to the line really bad and the line looks iffy. Of course, then you should be replacing the line too.
If you just heat it up mildly with a hand held mapp gas/ propane torch, and stay on the nut instead of the end of the hose, you're not likely to blow the hose