Can you bleed brakes through the master cylinder?

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I have this crappy car that's at a shop with a rusted brake line that needs replacing( near the back so its connected to the rear wheel cylinder) and the mechanic says that its really rusty under there (this is true) and he gave me an estimate for $440 for rear wheel cylinders etc etc. so either i can fix it myself or junk it....Because there's no way id pay that even he admits that it's not worth it. The question is cant i slap on a compression fitting and bleed out the breaks some other way? Because the bleeder valves are rusted out the only thing i could think of is drilling them out and bleeding them some other way. The car is a unibody K car so backyard mechanic raising the vehicle up is going to be a major problem as well.

Im really lost on this one can anyone help?

posted by  user187

I dont think you can bleed the brakes through the master cylinder. Someone correct me if Im wrong. That sounds like alot for rear wheel cylinders. Find another shop if you dont want to do it yourself. If you do it yourself you would save alot of money

posted by  bigdaveangell

Thanks i aprreciate it!

The thing is why do the cylinders have to be replaced at all? cant they be drilled out where the brake line is? In order for me to repair it myself i have to bring it to my mothers house to work on it where my tools are at. Which is a major tranportation hassle, I dont have a brake line bending tool and honestly am not versed in brake repair all so well? I dont really know this mechanic and i do have 1 that is somewhat of a friend. I think the tow charge there would be 50-75$. as I said im really lost what to do, if i bring it to my mothers it could turn into a real sideshow! Dont you think a broken brake line should be alot less then $440???wtf

posted by  user187

No, Sorry mate that aint possible, you can only bleed the brakes at the slave cylinders. What you can try and do is to buy second hand cylinders and having them re-sleaved. Might work out cheaper.

posted by  Arbitrary

So im not going to be able to drill them out? and just replace the bleeder valve? wtf does he have to do both wheel cylinders? he also said something about a crossover line? Maybe the lines are so rusty they should be replaced but all i need it for is another month until i can get something better.

posted by  user187

you could drill them out, but that means rethreading them and finding a larger bleed nipple. not sure about crossover line. Well if the problem is at only one brake cylinder then you only need to fix that one for now, but it is generally customery to fix both cylinders at the same time, like replacing both left and right brake pads even though only the one side is gone.

posted by  Arbitrary

I see, so the chances are even if i bring it to my mechanic he's not going to want to drill it out( which would be the bleeder valve *im sure that will probably break* and where the line goes into the cylinder correct? I mean really if i had a lift i wouldnt see why they couldnt be drilled out! Im really starting to think i should get a second estimate from my buddy now, and another thing he's not going to charge me for the estimate but wants the vehicle out of there by Saturday. So i have to make a decision by Friday......this kinda sucks it's not a job i want to do WHATSOEVER.

Can i bring this car to my friend and say "yes now this is all you do drill out the bleeder and also where the line goes in" I mean i cant tell the mechanic how to do his job right?

also thanks everyone for your help so far it's appreciated, I figured id get as much advice as possible and then make an informed decision and so far my friends are 50-50 on this. That's why i posted here because im at a loss on this one.

posted by  user187

Sure as long as your buddy knows what to do, but it is probably easier to just replace the whole cylinder with the brake line.

posted by  Arbitrary

Okay what would you say a fair estimate is for 1 rear wheel cylinder, and just replace that one broken line? and I tell my buddy just do that. (like i said where somewhat friends but still) so i assume he's not going to bust his balls to save me a few bucks. I know from past experience that drilling can suck. Maybe i should call up Auto Zone i had to replace a rotor and it was only like 20 dollars you can see my anxiety with this one. The car is either going to a junkyard or to the other shop but $440 that cant be F&#king RIGHT. If it's the junkyard im without a vehicle for a month probably. Unless i can finance something, and my credit sucks so it would probably be a buy here pay here sort of place and these places are shady.

posted by  user187

I think that's were the crossover line replacement comes in it's really hard to comment on that part of it because i cant look at the vehicle. Im pretty sure im going to have it towed out of there to my friends shop and roll the dice. The tow should be around $75 HOPEFULLY. and im hoping i can speak a little with Fred personally before he does his estimate, it would suck talking to him on the phone about it.

My best guess is $250 tops so we'll see what happens. The cars a POS but what else can i really do? How can i look at something new(used) if i dont have a vehicle to get around! BTW it's a 4 cylinder 1986 Dodge caravelle :ohcrap: but it only has 80,000 on it......it is sort of a tool but i cant complain for what its accomplished. I may be throwing my money away fixing it but the worst that could happen is another high estimate and me back to junking it.

This should be interesting to see if my guesstimates right! I was hoping a few of the pros could give me a ballpark figure but i guess not.

posted by  user187

ok so 30 dollar wheel cylinders and you wanna get used ones, i mean cmon 2 hours labour 2 new wheel cylinders, break the old flare nuts off if you have to and make a new flare on the end, truly someone out there remembers how to make brake lines,

posted by  BanffAutoSpa_ap

So what do you think around $250 right? I dont mind having to pay that just because of the hassle and hoops id have to jump through doing the job myself. The cars great in the snow and the winters coming up.

posted by  user187

well just curious but what kinda car is it?

posted by  adamc44

I know you guys are f**king kidding... of course you can bleed your brakes through the master cylnder... you hook up a machine that forces fluid into your master cylinder, as its pressing the fluid you remove the hoses from each of the calipers (one at a time) let it run clear (ie replace all the fluid).

I just learned this tonight in class.

You can also remove the master cylinder, put it in a vice grip and bleed it with a syringe.

posted by  TheFieroKid

Is this supposed to be humorous? Jesus anyway im having the car towed to the shop on Friday, and if I get a sky high estimate i'll just do it myself. Im sorry but the way i look at it this other guy wants $100 an hour and his estimate was ballpark "saying i dont know what would happen when i start the job" sounds more like he doesnt want to do the job and is going to soak me if he does. If your a legit auto mechanic you may have jobs you dont want to do but your running a business, and taking on a messy job is part of that.

I probably wont get an estimate till next week so i'll report back. should be interesting to see how this shakes out.

posted by  user187

Excuse me?
I just watched a video on it.



Maybe people shouldnt post unless they are familure with the topic.
If my brake instructor whos been working on brakes since the 60's is wrong... mabye he shouldnt be teaching.

posted by  TheFieroKid

ok i've browsed through the posting and looked up the price of wheel cylinders under $20 usd under 30 cdn
on some of the post they say you can bleed the master cylinder (yes) but you are replaceing/repairing wheel cylinders/brake lines these are at the rear and lower than the master so without the ability to let the air out of the wheel cylinders how are you going to bleed them (you can't)unless you replace the brake lines to the wheel cylinders and bleed them here(this is not the best but will allow if needed time to purchase new wheel cylinder's) the brake line can be purchased premade in different length's so measure them out and spend the money to buy them this is easy for most ppl to do on there own with limited tools(small vise-grip's for the old fitting on the old lines and a 3/8 or 10mm wrench to install the new lines) biggest thing is don't let the master cylinder run mt then you will need to bleed it as well

posted by  osborste

:mrgreen: the answer is yes you can bleed the brakes by using the mastercylinder, but you still have to open the bleeder nipples in the wheel cylinders and calipers, if they are rusted they will break and will have to make new lines

posted by  BanffAutoSpa_ap

Thanks everyone for your help. I had the vehicle towed to my friends shop unfortunately I couldnt do the job because public transportation ends with me trying to hitchhike a ride 10 miles. There were also other problems, and i had to tell what happened because Freds towed it so they know exactly what the estimate was(also someone else had a vehicle towed out of there according to his wife). Which kind of sucks he's an honest guy but that wasnt good at all. There was no way around it and the Car had to be out of there before the weekend. I told Freds wife just do the job and i dont want an estimate=just get it done i trust him and whatever he says i'll accept it.

Im praying that im not screwed on this repair. I plan on losing my whole weeks paycheck now. WONDERFUL i just hope the f*^king thing doesnt start nickel and diming me to death, from now on im not driving unless i have to, with gas prices the way they are this isnt such a bad thing i guess.

When everything is over i will report back on what the final bill was and what had to be done to get the car back on the road.

posted by  user187

Okay he just called and it was $408 and that's including the tow! Now you can see why i was miffed! I havent got the work sheet yet but this is acceptable to me, in fact he fixed my horn as well!


Thanks everyone so much for your advice and help!

posted by  user187

The rear slave cylinders should be fairly cheap to buy. If you replace them you wan't have to worry about corroded bleeders. You can do the old foot on pedal routine to bleed air out or take it to a shop where they can force feed the master cylinder with fluid while it drains through the slave cylinder bleeders.

posted by  Wally

heres a tip, i just installed some raybestos wheel cylinders in a car, and went straight to the pressure bleeding..(one guy in the car and me one the bleeders) guess what, they did not bleed out all the air, i brought the car in 3 different times and finally got pissed and started to gravity bleed while i had coffee, for some reason the wheel cylinders would trap air above the bleeder and absolutely would not purge the air with a force pressure bleed, but the gravity bled just fine and it all worked out, the tip of the day, just gravity bleed them first and then get the guy to pressure bleed, maybe it was just this car but man did it ever waste alot of time,

posted by  BanffAutoSpa_ap

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