So I just replaced my calipers and upgraded to SS lines, but after that I had a VERY soft pedal and some fluid leaking, went over all the connections re-bled the brakes and have good pedal feel again, but am still loosing fluid.
My uncle who I work on my car with, thinks it may be the master cylinder due to some rust on the booster and that I'm either leaking it or burning it off

any suggestions before I just get another master cylinder? any suggestions on other things to replace while I'm there?

'86 Base 4lug 1 pot calipers for info on model

 

Kind of obvious. You say you had "some fluid leaking." Replace whatever it was that was leaking. Leaks don't fix themselves, and eventually, you'll lose more fluid and the soft pedal will return. A new master cyl (if that's the leak) is less than $50.

 

i just replaced my calipers with 4pot, and went with stainless all around.
i also replaced my master cylinder.
at first i had nooo pedal, but i let her sit overnight, and all the little air bubbles collected into one and POP out it came!
id go with the master cylinder, but double check to make sure you tightened everything down.

 

I think what he's trying to say is that the fluid level is going down, but he cannot see any leaks.

If there are no leaks, it has to be the brake booster, and as far as I know, brake fluid should not be going in there unless you have a bad master cylinder, just like you said.

 

Did you bench bleed the MC first? If not..this could probably have been avoided if you had bench bleed the MC before installing it in the car.

If you are loosing fluid...definitely leaking...trace all the lines and find the leak and replace what is necessary.

If you are NOT loosing fluid and the pedal keeps going to the floor, then it's almost definite to be the master cylinder.

 

Black plague got it, if it was as obvious as dripping from the master I wouldnt have questioned it, but its not too obvious where its coming from. The main theory we have is that giving it a good bleed and replacing everything cleaned all of the crap out and sprouted a leak, but thats no set theory.
I have gone over and double checked all the connections again, I thought I mentioned that in my first post but I guess it wasnt too clear :/ , but yeah theyre are all good and not leaking.

I just got back from driving it agin, junkyard hopping for a few cars . Pedal still feels good but yeah theres less than there was before

So I was coming on here to see if there were any other ideas or similar problems others have occured before I just go replacing another part along the line hehe , I'm going to end up with a 20 day old brake setup on a 20 yr old car :P

Would you suggest I replace the booster too? or would the master be sufficient?

 

Ive never heard of a booster going out. I dont think it's a very common occurance. I would think MC myself.

Have you tried to look into the booster or underneath it to see if there is any fluid there? If fluid is going into the booster fromt the MC, the MC needs to be replaced or rebuilt.

 

I was just getting some stuff out of the car so I took some pics of the Booster, I doubt its bad too, but if its the seal b/w the too, I wanted to know if a new seal/gasket will do or to be on the safe side and replace the booster too, or else I'll just sand and repaint it to prevent further erosion and watch it and whatnot.

heres the pics of the booster/master

 

Dude...that MC is rusted to all hell and back! Replace it. And replace the seal between the booster and MC also.

I really doubt the booster is bad.