RTH: My brake MC makes me want to kill something

[deaddrift]

After wrestling with a soft brake pedal for an hour or so, I've discovered I have a problem. The reman MC is leaking at the ground down hardline fitting (the rear one). I have cranked down both the hard line nut and the cylinder body nut that receives it. Not sure if it's a bad MC or just a jingus grind/repair on the hard line nut. Shouldn't the nut on the hard line work OK the way it is?

Anyway I am removing the remanufactured MC AND the hard line and replacing both. I am more than a bit frustrated that wrapping up my axle rebuild is still getting hung up by these brake issues. Wish I was faster with diagnosis and repair, everything takes me forever.

Can I just crank on the old hard line nuts with a vise-grip to get them off? I know I'll damage them but it doesn't seem to matter now. Or do I buy a blank line and use my old nuts... because that won't work if my damaged nut won't seal.

I've been using Baxter Auto Parts as well as NAPA. I got the MC at NAPA but inkpot wrote that "BAP sells hard lines." Is this referring to Baxter? Well I'll find out tomorrow.

Thanks again for all the help. And thanks ntsqd for coming over to look at this thread, much appreciated.

 

[langsen]

The nut you ground down should work fine. The flare at the end of the tube is what creates the seal. But if it gets over-tightened it can deform and leak. Harbor freight has a cheap set of flare nut wrenches (99993, $10), makes it a lot easier to work with these fittings.

If you need to replace the fitting, NAPA and almost every auto parts store sells brake tubing already flared in all different lengths with fittings attached. Probably around $5 for something that short. Bending it can be tricky.

Did you replace (or anneal) the copper gaskets on the MC outlet plugs? Could be leaking there if you reused the old gasket.

 

[deaddrift]

Thanks for your advice langsen.

I figured that the line worked the way you describe, but I've been unable to keep the back seal from leaking no matter what I try, tighten hard or soft. I have probably overtightened it by now, since I've cranked both the line nut and the MC housing receiver nut as hard as I can in an effort to stop the leak. I'm thinking now that I may have damaged an internal o ring, but it never didn't leak so I'm not sure.

Thanks for the HF tip, most of the tools I've bought there have been dreck at best, but the prices sure do beat NAPA or Baxter. I believe I can bend line OK, I think I have a good touch for that kind of thing. Tips and suggestions more than welcome of course.

I bought a whole remanufactured MC housing. The only pieces I replaced were: I put my old reservoir, connection hose, washer, and reservoir attachment through-nut on; I replaced the MC-to-booster gasket with 1/64" NAPA generic gasket paper; and the new front calipers.

When I tried to bleed the system last time, I was getting leaking from the back (rear) line at the MC regardless of how tight I made it. Hence the replacement idea. Let me know if I'm on the wrong track.

 

[LAMBCRUSHER]

at this point you may want to just swap the rear line. you may have damaged the seat, but prolly not. I'm gunna guess that almost any similar vintage toyota has lines that can reformed to fit>junkyard. are you certain it is leaking and that you weren't seeing the delayed dribble back of fliud caught between the line and flare nut body on the atmosphere side of the sea?

 

[deaddrift]

Well at long last I have managed to procure a brake master cylinder that DOESN'T leak and have successfully installed it in the cruiser. The brakes work great, I bedded them in this afternoon.

Only problem is that the right rear wheel will not bleed, barely any fluid will come out even when the bleeder is so loose it feels like it will fall out. My rear brakes need some attention but that's going to have to wait until I enjoy this job for a week or two.

If you have any insight into my blocked rear brake line I'd appreciate the advice.

 

[langsen]

Glad to hear you got the MC sorted out.
As for the right rear brake, if you haven't bled that brake recently, the bleeder could be clogged. Unscrew it completely and poke something through the hole to clear it.

 

[inkpot]

2x this. If still no luck, then you may have a badly rusted/blocked wheel cylinder. You could try loosening the hard line to that wheel to see if you get good fluid flow on that side of the brake. John