Brake line nuts too tight !!!

[AC439]

I think my master cylinder is original. I have a very slow leak at the end of the master cylinder (the side that goes to the booster) which I have to top off fluid once every maybe 6 months. I've got a reman master cylinder and was ready to do the job today. I also bought a set of metric brake line wrench.

After I've got everything ready, I was trying to unbolt the brake lines from the body of the master cylinder. It was so tight that even the brake line wrench would widen itself and the nuts won't turn. I hate to use excessive force to turn the nuts. I don't want to make the matter worse. So, I'm stunned without accomplish anything.

How in the world do you untighten the brake line nuts. What is the worse case scenerio if I mess up and round the nut?

How much worry if I have to continue driving with a slow leak like this?

[shepherd79]

the worst case scenario would be you would have to cut the lines, replace the master cylinder, get new bolts and reflange the line. you may have to bend them a little since they get shorter.
Or you can get all new brake lines.

[DBMaster]

What will probably happen is that when the weather gets hot and the engine bay gets very warm your brake pedal may go to the floor. Your M/C piston seals have started to go bad. The car will still stop, though, so don't panic. Even replacing my brake fluid every 30K miles like Honda says to do I have had to replace my M/C about every 100K miles. I would try some sort of penetrating lubricant (liquid wrench, PB Blaster, etc.) on the flare nuts. Beyond that, I don't know. You should definitely try to get it replaced because it will only get worse.

[88Accord-DX]

PB blaster & use a flare nut wrench. If you round the nut off, then your in trouble. Either a new line or cut it off & flare the line out for new fitting.


Couple pics to add to advice.



Example of using on a brake line.

[AC439]

I will try to use some PB and see if this will work. I already have the flare nut wrench (I called them brake line wrench) but the nuts are so tight that the wrench started to widen and about to round the nut.

I will post result. Thanks!

[AZmike]

You could use a vice grip to keep the wrench from opening up too far.

[AC439]

You could use a vice grip to keep the wrench from opening up too far.

Thanks. I should have thought of that too !
Will try and let ya'll know.

[AC439]

Well. I tried again and still have no luck untighten the nuts. There is not enough room to use to vice grip to keep the wrench from opening up.

I used WD40 instead of PB. I'll let it soak for some more time and see if it will work.

[shepherd79]

wd40 is nothing but pam oil inthe can. use pb BLASTER.

[AC439]

Finally, I finished the job. Using PB soaked over 24 hours. Bought 2 vise grips 5"&7". There is simply not sufficient space to put a vise grip over the flare nut wrench. So I ended up using a plumbing wrench to open the front nut. It was risky but I did it carefully and slowly so I saved the nut. For the rear nut, I was able to use a regular 10mm wrench (a quality craftsman wrench) to have it open.

After bleeding the cylinder and put it back on, I started to bleed the brake lines. The bleed bolts were also not easy to loosen. Definitely used PB on them. The L front bleed bolt is completely clotted so I had to take it out and clear it, put it back on and bleed the line. The R front bolt rounded with a 10mm wrench. Ended up using a long 10mm socket to loosen it (of course with PB again).

The whole job took me 4 hours. But the new brake is firm and tight and feels brand new. And I found the flare nut wrench and vise grips were not useful in my situation.

Thanks everyone jumping and helped.
-AC