I have an 81 Chevy pickup C10 that I was replacing the brake hose on. In the process of trying to take the brake line loose from it I started to twist the line when I thought I had finally started to break them loose from each other.

I was able to go to a local pull-a-part place and get the replacement brake line I need, but once again I wasn't able to get it disconnected from the hose so I just cut the hose and pulled it through the frame so that the line was intact. What is the best way for me to loosen the brake line from the hose?

I also was not able to remove the brake line currently on my truck from the spot where the brake lines intersect ( I have no idea what the part is called.) Also what is the best way to clean the brake line before I install it? I believe I've been told rubbing alcohol would be the best.

2 Answers 2


By far the best chemical rustbuster I have found is PB Blaster. If you don't have access to a torch or if it is in an area that heat would cause problems this is the stuff I use. The key point is patience. I spray the part and let it soak for 15-20 minutes. If it still won't turn spray it again and wrap a small piece of rag around the fitting and soak it with PB Blaster. Let it soak overnight. You may have to repeat it several times. Once it starts to turn spray it again. If it starts to get tight again turn it in the opposite direction 1/4 to 1/2 turn then try to back it off again. Repeat the process always stopping when the fitting gets tight. When you reassemble it use neversieze or teflon tape on the threaded part of the fitting. This will make it easier the next time. Prior to reassembly spray the parts with brake cleaner to remove any oils that could contaminate the brake fluid.

  • So applying heat with a flame would work to break it lose as well? Aug 16, 2012 at 21:20
  • 1
    Yes but you must be very careful. Brake fluid is highly flammable. The rubber hose could catch on fire, you may be close to fuel lines or other flammable parts and if the parts are assembled you have to be concerned heating a liquid ( the brake fluid) in a closed container such as the caliper. If you haven't done something like this before it is best to get assistance from a friend that has.
    – mikes
    Aug 16, 2012 at 21:29
  • Thank you. I wasn't sure if brake fluid was flammable or not I don't think I'll try that on the line still in the truck, but the one I pulled from the junk yard should be ok once I clean it out. Is rubbing alcohol ok for that? Aug 16, 2012 at 21:53
  • Double +1 for PB Blaster and the fire warning.
    – Bob Cross
    Aug 20, 2012 at 16:07

I upvoted the PB Blaster. It's perfect for this situation.

The only thing I'd add is that it's tremendously important to use to the correct tools for these parts: six point flare nut wrenches. Especially on these underbody parts that have been rusting since the 80's, using regular open end wrenches, or channellocks, or vice-grips or even 12 point box end wrenches is just asking for trouble. If you're going to work on hydraulic lines, which brake lines are, you need flare nut wrenches. They make a world of difference.

Just my two cents.

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