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Discussion Starter #1
ok, so i noticed that i was leaking brake fluid recently, i popped the hood and saw that it was all over my master cylinder and brake booster and even under my hood (on top of the mc). i looked a little closer and noticed that where the booster and mc connect there is rust and it looks like it was flowing down the brake booster from the mc, i also noticed that there is a small hole in the booster under the mc. does anybody have an idea of what it is? is there a way to fix it? or do i need a new mc, booster, or both?
 

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you probly need only a new mc, the booster doesnt hold fluid.
 

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You need to fill in some details about your Bronco under your Registered User name so we know what year your Bronco is etc. etc......OK......

Usually when there is a leak with the Master Cylinder the brakes begin to fade and the pedal will go all the way down to the floor if you press on the pedal steadily meaning the fluid inside the MC reservoir is passing over the O ring/s on the piston shaft so now there's no sustained pressure throughout the system, the pedal fades and at some point if you continue driving with this condition, you will NOT BE BALE TO STOP THE VEHICLE so don't take any chances.

Is it possible you "overfilled" the MC and the air blowby is pushing the fluid round....?

First "clean" up the mess with brake parts cleaner and after it evaporates take a look right at the point where the MC bolts to the power booster and see if the fliud is leaking from the back of the MC, a common spot and if so it's time to either rebuild or replace the MC.

Using a pistol grip vacuum pump bleeder you can do the job by yourself BUT remember to "bench bleed" the master cylinder BEFORE you install it either using the bleeder plugs that come with the MC or make 2 short, curved steel brake lines with fittings for the MC. The lines should curve over sort of like this (n) so when the MC is filled you plundge the piston with a large screw driver continually until ALL the air bubbles are gone keeping the MC topped off and not suck in additional air. Once you have completed the bench bleed , top off MC putting the lid on while installing it then once it's all hooked up take off the lid, bleed the system keeping an eye on the fluid level.

If you don't do it this way and install the MC, you will be there until your "retirement" ...lol lol.....trying to get a good pedal, then bleed the system according to the Haynes Manual and you should be good to go, test drive naturally and rebleed if necessary.

You can park in the driveway if there is a downward angle point the nose of the BKO downward to help with an initial gravity bleed while installing the MC, your call.....with the self bleeder it's probably not necessary....?

If there's any rust or damage to the brake booster maybe it's time to replace it, there's an F350 MC/Booster upgrade if you "search" here you might consider OR get a JY booster...O'Reillys offers a Cardone reman Booster only for $75.99 #54-74211 or Cardone MC with Booster # 50-9315 for $91.99 plus tax they also offer Wagner mfg without pricing but that's for an 86 BKO....check around for pricing.


Good Luck ~ :thumbup
 

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Discussion Starter #5
ok, so i pumped the brake pedal a couple of times and it restored pressure... also notice rear driver side drum is leaking brake fluid, will post pics soon.
 

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A rear drum leak is most likely the wheel cylinder, fluid coming thru the seal so I would replace "both" wheel cylinders and be done then see how things are at that point whether you need to replace MC/Booster etc.

When replacing wheel cylinders you're going to have to tear down the brakes shoes etc. so clean and check everything (parts) that they're in good working order and make sure the "bolts" for the backing plate that go to the axel flange are properly torqued otherwise they can become loose over time and when you brake backwards/forwards they will "ratchet" and maybe snap off a bolt/s, brakes become very sensitive, grabby and wheels lock-up with just slight braking.

Once wheel cylinders are installed , rebleed system farthest back from the MC to front etc. etc.

They're not expensive!

Good Luck ~ :thumbup
 

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You need to change the master cylinder and both wheel cylinders on the rear. The MC should be about $30.00 and the wheel cylinders should be about $10-$12 each. Start soaking the wheel cylinders down where the brake line goes into them with some penetrating oil now. They are usually a real pain in the butt to get off of there.
 

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Isn't it pretty possible for a leaking MC to leak into the booster, and then corrode the booster?
My MC was leaking for a while last year, then my booster followed just a few months ago. The booster looked just like his does, leak and corrosion in the same spot around the MC mount.
 

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looks like a bad MC to me. And do the cruise recall while your at it.
 

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Isn't it pretty possible for a leaking MC to leak into the booster, and then corrode the booster?
My MC was leaking for a while last year, then my booster followed just a few months ago. The booster looked just like his does, leak and corrosion in the same spot around the MC mount.
Yes it is posible. but it wont corrode the booster, it will weaken and slowly destroy the diaphram thats inside the booster housing.
 

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X2 with Bruno2 and Ewgoetz.......PB Blaster is your best friend AND use a "brake line style wrench" on fittings etc. otherwise you could round a fitting nut/s......PITA....


Good Luck ~ :thumbup
 

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Discussion Starter #14
i priced the parts and a new mc is ~50$, 100$ w/ booster and the wheel cylinders are ~10$ each... gotta save till i can afford it haha
 

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You can always get the MC and wheel cylinders now, that that way you can stil drive it but you will eventualy have manual brakes when the booster goes out. Its better to beable to stop by trying to put yur foot throught the floor than when the MC goes out completely and you cat stop at all.
 

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change the Master cyl, this happened to my friends booster. Simple fix.
 
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