Master cylinder puking fluid

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K

krabysniper

Guest
My master cylinder looks like it is leaking fluid from the cover, also when you check fluid levels after a couple days driving around, the front chamber will be empty and the back looks pretty low, can fill back up with fluid, brakes feel excellent, but it will puke fluid from the lid by the loooks of it. Any one else ever have this problem. Replaced the master cylinder but still doing it. Brakes are 12x2 1/2 rear drum and 11 3/4 front. I havn't installed my aftermarket proportioning valve and the rest of the brake system is stock albiet all new pieces. I just don't get it. Is this a cover leakage problem or is it actually pumping the fluid out due to a bad combonation valve? Anybody, thoughts, ideas?
 
35+ views and still nobody has even a thought, please do not tell me that I know more about brakes than anybody else here? Somebody has to have had a simialar problem at some point in time.
 
I myself haven't heard of this. But it could possibly be another bad master. It's not unheard of. Have you checked to make sure you have no weeping around fittings with someone holding the pedal. And make sure you have no lines real close to your exhaust.
 
hey krab i would have to personally say its sounding like your cover isnt sealing properly.. but i have never heard of it just gushing-leaking out like you describe, maybe it is a faulty master.. whats it hurt to change it again..

Do you still haev brakes?
all around?

ur portioning valve would have nothing to do with it, if that was wonky you would just have really touchy brakes. You dont have a cheesy chrome master cover do you? those things are gay and will prolli leak and would explain why you leaked before and now. if not.. i say change the master one last time.


Cerwin
 
i would have to agree with Cerwin on this one. Maybe try changing the master cylinder just once more and see if that solves your problem. If not then further diagnosis is needed.
 
Nope, no cheesy chrome covers for me. The cover came on the master cylinder when I got it. Brakes work MINT except for this one problem. It will puke the fluid out until the front chamber is completely empty, then I notice a drop in braking performance because the rears arn't doing their part anymore. Fill the resivoir up and drive it (without bleeding even, and before anyone says it, NO, that isn't the problem, I tried waisting my time and a lot of fluid rebleeding the brakes the first half dozen times or so.) and they will come right back, working just perfect except for the fluid spooging thing. I know plenty about brakes and this has me utterly baffled. I am going to try another master cyclinder though. Still under a warranty so it will only cost me the time to change it out and bleed them. Really really strange. :sad1:
 
this is gunna kill me man, until i figure this one out.

power or manual?


does it leak when your ON the pedal or coming OFF the pedal,
this has to have something with the master, the valve no releasing the pressure or something

huh.. wierd.. let me know
 
are these masters rebuilt or new? your right, that is a weird one. do you leave about 1/4" for expansion? did you bench bleed them?
 
redfastback said:
are these masters rebuilt or new? your right, that is a weird one. do you leave about 1/4" for expansion? did you bench bleed them?
Click to expand...

Yes, reman, yes bench bled defore hand, I am aware of the proper fill level and is all I put in it. Havn't messed with it as I havn't relicensed it so I cant drive it at the moment. Need to make more money so I can afford to play with it more.
 
krabysniper said:
Yes, reman, yes bench bled defore hand, I am aware of the proper fill level and is all I put in it. Havn't messed with it as I havn't relicensed it so I cant drive it at the moment. Need to make more money so I can afford to play with it more.
Click to expand...


want me to drive it for you in the mean time???

lol
 
is brake fluid slung all over or just around the master you might want to yank the wheels off and check your wheel clynders inside the drums they sometimes leak and you can never tell bc it leaks out on the wheels and is slung off
 
If you haven't allready check the face at the top of the reservoir with a steel ruler to make sure its flat, also check real close to see if you've got a crack on the sealing face or down the side
 
Wow I thought it was only me that had the same problem! I bought a new master cylinder about a year ago and I have the same problem with fluid coming out of the top. the fluid never goes below half full though and it looks like my cover is a little bent so I will try to bend it back when I get a chance
 
Your not the first nor will you be the last to have this problem. I too have had this problem and have replaced two good master cylinders trying to resolve this to find out that the problem was with the hold down clamp thing. It appears that some of them have lost there stiffness. After changing out the third master cylinder it became clear that the cap wasn't being held down tight enough. That clamp should snap on taking some effort. Give it a try, it took care of my problem. :lol:
 
Well, I took a very good look at my reman MC, man oh man, I cannot believe they get away with selling this crap. The edge along the top is so pitted it isn't funny. So I am using a temporary fix (wanna go racing this weekend and need the car to be able to drive 200 miles round trip to the track) I used black silicone and laid a nice small bead along the edge of the MC then laid waxed paper over it and snapped the lid in place. I'll give it a few hours to cure some then I can pull the cap off and let it finish curing over night, also made some adjustments to the "spring" that holds the lid down so that it retains it with a little more ummppf. If this cures the leakage I will make a more permanent fix for it this winter, I think a nice layer of JB weld along the edge smoothed out to fill in the pits should do the trick. I will update after this weekend and let ya know how it goes, and if this is the fix I will make a little tech right up on my JB weld fix so anybody else who runs into this will be able to "FIX" their re-man master cylinder BEFORE they go to the effort to install it.
 
glad to see everyone give some ideas here thats what i like about this place someone has had the same problems and has some ideas. was going to tell u to check the seal surface for severe pitting i have the same problem on my demon. i took some solder and melted it along the edges and smoothed it with 1000 grit. seem to hold so far i have manual drum breaks and have to pump the s##t out of them sometimes causing the cap to leak. i thought it was my headers making the fluid boil. but nope these remaned mc are getting so worn out that u find warped caps bent hold downs and badly pitted castings. another thing u can do is see if any parts stores can still get the older bolt down style cap masters. good luck
 
Had the same problem on my Dart Sport, man disc, I replaced the rebuilt m/cyl. with a new one from NAPA. No more leak!
 
New parts are the only way to go when available (of course the keyword is-AVAILABE) and a new Mastercylinder is availble from NAPA for just a few bucks more than a reman. I also had a reman that leaked due to the top edge being pitted like Kraby's. My new one from NAPA is perfectly machined and don't leak a drop.
 
I had the same problem with my scamp break fluid all over the master.What i did was cut a couple of shims the same size as the rubber seal on top of the master.I took the rubber seal out and put the sims in the cap then put the rubber seal back in the cap no more leaks.The cap was not tight enough on top of the master .Good luck
 
I recently posted a message regarding this same problem with leaking
on my son's Dart Sport. I'm considering installing one of the newer, lighter, aluminum master cylinders with the screw-on caps, found on later model vehicles. I understand it will require a 2-bolt to 4-bolt adapter, but I still haven't gotten a bead on the correct replacement M/C to fit an A-body.

Anyone done this swap who can provide a good part number, or at least
the vehicle it is listed for?

Jerry
 
[QUOTE='74 Sport]I recently posted a message regarding this same problem with leaking
on my son's Dart Sport. I'm considering installing one of the newer, lighter, aluminum master cylinders with the screw-on caps, found on later model vehicles. I understand it will require a 2-bolt to 4-bolt adapter, but I still haven't gotten a bead on the correct replacement M/C to fit an A-body.

Anyone done this swap who can provide a good part number, or at least
the vehicle it is listed for?

Jerry[/QUOTE]
http://store.summitracing.com/partd...DCC-5249315&N=700+4294922533+115&autoview=sku

http://store.summitracing.com/partd...DCC-5249270&N=700+4294922533+115&autoview=sku
 
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