Flushing the brake System
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Flushing the brake System
I have a '69 250. Recently, after not driving it for a couple of weeks. I noticed that the brakes were very spongy and faded. I do admit it has been at least 6 months since i have checked my brake fluid.
When i opened the master Cylinder, the larger bowl towards the booster was nearly empty. But the worst part was that inside of the master cylinder was rusty looking and the remaining fluid was kind of milky brown looking. How is the moisture getting in? Any suggestions on a fix. Should i replace the master cylinder or just flush the sytem?
When i opened the master Cylinder, the larger bowl towards the booster was nearly empty. But the worst part was that inside of the master cylinder was rusty looking and the remaining fluid was kind of milky brown looking. How is the moisture getting in? Any suggestions on a fix. Should i replace the master cylinder or just flush the sytem?
Lead Driver
Joined: Jan 2003
Posts: 9,893
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From: Ohio
Yup, replace the master cylinder. If it was down, it was for a reason. One: leaky wheel cylinder or two: leaking out the back of the master cylinder. In which the master cylinder needs replaced. They are cheap and pretty easy to change.
You'll need to bleed the whole system anyway, so get plenty of fluid and bleed it till nice clean fluid comes out at each wheel.
You'll need to bleed the whole system anyway, so get plenty of fluid and bleed it till nice clean fluid comes out at each wheel.
Logistics Pro
Joined: Jan 2011
Posts: 4,762
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From: Antelope Valley ,CA
dot 3 fluid is known to collect moisture , mostly from condensation . that's why it is recommended to replace the fluid, but no one does .
i'd get a mighty vac and pull the fluid out of each wheel till it comes clean then replace the master cylinder .
start with passengers rear , refill master with new fluid till clean
move to next closest wheel.. repeat
i'd get a mighty vac and pull the fluid out of each wheel till it comes clean then replace the master cylinder .
start with passengers rear , refill master with new fluid till clean
move to next closest wheel.. repeat
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How do i know if the booster is ok. With the brakes in this condition, when i press on the brakes, i hear like air leaking somewhere around the brake pedal. Is this just the fact that the brake pedal is going all of the way down due to the low fluid. Hopefully, the booster is ok.
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From: pine city washington
flushing brake system
the brake system usually absorbs water through the flexable hoses that is why it is recomended that you change them to flexable stainless with teflon inside and definatly flush the whole system and change the wheel cylnders all of them don't buy used and change your brake shoes and or pads you can have the drums turned once or twice but no more than that i have a 69 f-250 with drum brakes all around and it still stops on a dime.
Lead Driver
Joined: Apr 2011
Posts: 6,399
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From: El Dorado, Arkansas
If the MC was leaking out the back and over into the booster, the brake fluid will damage the booster diaphragm.
It's normal to hear a hiss coming from the booster when you first push down on the brake pedal but, you shouldn't hear a continuous hissing.
My truck did the same thing as you describe, with regard to the MC, when I bought mine roughly 4 years ago. I replaced the old MC with a new cast iron MC (at that time) and added a brake booster with all wheel drums.
Recently, I've swapped the front drums out for front discs and pitched the cast iron MC for a modern aluminum MC. It's much lighter, doesn't rust (inside or outside) and the top doesn't have to be removed to see how much fluid is inside. This reduces the introduction of dirt and moisture from getting into the brake system.
It's normal to hear a hiss coming from the booster when you first push down on the brake pedal but, you shouldn't hear a continuous hissing.
My truck did the same thing as you describe, with regard to the MC, when I bought mine roughly 4 years ago. I replaced the old MC with a new cast iron MC (at that time) and added a brake booster with all wheel drums.
Recently, I've swapped the front drums out for front discs and pitched the cast iron MC for a modern aluminum MC. It's much lighter, doesn't rust (inside or outside) and the top doesn't have to be removed to see how much fluid is inside. This reduces the introduction of dirt and moisture from getting into the brake system.
Fleet Mechanic
Joined: May 2001
Posts: 1,396
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From: Cupertino
Fix your leakage problem as above.
Then, buy one of those suction guns and suck the master cylinder dry at every oil change. Wipe crud out the first time. After the third time the fluid will be as clear as gin.
By the way, hide a key in the master cylinder.
Toothless Jake taught me that one.
Then, buy one of those suction guns and suck the master cylinder dry at every oil change. Wipe crud out the first time. After the third time the fluid will be as clear as gin.
By the way, hide a key in the master cylinder.
Toothless Jake taught me that one.
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