Does this make sense?

[Mr Lee]

 
So, I've been fighting a brake fluid leak at the rear fitting at the master cylinder for months now, but the front chamber is where the fluid level drops. Shouldn't the rear chamber be low on fluid? 

Sometimes it seems like fluid gets low in the front chamber and higher in the rear chamber.  So i take a spoon and put the fluid back into the front chamber. 

And as for the leak, I have been tightening this fitting for months, a little further each time and it still leaks.  Both mating surfaces look fine to me.  I even tried teflon tape on the threads as a last resort. Still leaks. Any advice would be appreciated. 

I think my next move is a new line and / or a new master. 



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[Mrbill426]

 Maybe the fluid is being exchanged front to back by leaking past the piston cups?  Teflon tape will not fix a leak in inverted flare fittings.

[jimynick]

The flare nut looks like they're stainless; are they? The stainless lines are a real SOB to get to seal and one trick is to remove it and put some copper never-seize between the nut's face and the back of the flare. The thinking is that the SS lines are harder than MS and using the never-seize allows the nut to exert more force on the flare, as it's not galling. Obviously a good flare wrench is your friend here and good luck! 

[Mr Lee]

The flare nut looks like they're stainless; are they? The stainless lines are a real SOB to get to seal and one trick is to remove it and put some copper never-seize between the nut's face and the back of the flare. The thinking is that the SS lines are harder than MS and using the never-seize allows the nut to exert more force on the flare, as it's not galling. Obviously a good flare wrench is your friend here and good luck! 

That seems to make sense, thanks.  I had all stainless lines prior to this but scrapped 90% of them because I had leaks out the wazoo.  These are plain steel now and this is the last leak i have left to solve. I can't tell if it's leaking out the back hole of the nut or if it's leaking through the threads.  Will try to narrow that down

I made it tight (or what I thought was tight), marked the nut with a paint pen, and over the course of time, in small increments, i can see that I have tightened it a quarter turn more!  That's a lot.  Almost feels like its about to snap, but doesnt.  I guess im gonna just keep tightening it til it either breaks or seals.  Dunno.  Shrug.


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[anlauto]

Could be like a hair line crack in the casting that you can't see....I would swap the master if it's not some rare "correct part number" type thing

[mopar jack]

I have the same issue with fluid going low on the rear reservoir and going high on the front. I run Dot 5 and I think it is the problem. I changed the master cylinder twice but same problem so I just top it off when needed.

[JS29]

If the front brake's are disk, it's normal for the fluid to go down as the pad's ware. the piston sets out farther in the bore, so the fluid is occupying that space.   

[Burdar]

If the front brake's are disk, it's normal for the fluid to go down as the pad's ware. the piston sets out farther in the bore, so the fluid is occupying that space.

Except the larger reservoir is the disc brake side.  The smaller drum side of the master is the one that is losing fluid level.

[MoparLeo]

If the fluid levels in the reservoirs are swapping sides, it is internal. Safest to just replace with a NEW, not rebuilt master. Make sure that the lines mating surface at the flares is not deformed from over tightening. If so just replace instead of fooling with it. Make sure to rebleed the entire system just to check it off the list. Adjust rear brakes first.

[Mr Lee]

I am running Dot 5 also but I don't think that's the problem. 
Yeah i think I am just gonna get a new master cylinder from Bill Rolik.  And a new line. 
Thanks for all the input


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[jimynick]

Seriously, try the never-seize trick. Mine were leaking and we cured it. All you've got to do is spin the flare nut loose, goop it and reinstall. What've you got to lose?