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Jemattson18

'54 Chieftain Master Cylinder Problem

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Hey guys, I'm currently working on replacing the entire brake system on my 1954 Pontiac Chieftain. However, I've been running into some problems with the master cylinder. I ordered one online a few weeks ago and I installed it and bled the brakes. Whenever I pressed on the pedal nothing happened with the shoes and there was just a little geyser inside the reservoir of the master cylinder. I assumed the master cylinder was defective, thinking that fluid is just leaking past the piston. I bought another one and the same thing happened. Is there something wrong with the master cylinders or am I just doing something wrong? Any help would be appreciated.

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The geyser in your reservoir may be caused by trapped air pushing fluid back into your master cylinder. You did not mention what type of brake bleeder you used. I have found that some brake bleeders don't work very well on some older cars. My vacuum bleeder works very well on my Citroen, but it fills the brake lines with air on my 1949 Chevrolet pickup resulting in a problem very similar to the one that you described. A flexible line immersed in brake fluid works better on this vehicle. Perhaps you should try a different type of brake bleeder. You might have better luck.

Drew's vehicles:

1949 Chevrolet pickup

1951 Henry J

1958 Lambretta 150LD

1961 Bianchi Orsetto

1965 Citroen 2CV(Deux Chevaux)

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I initially used a vacuum bleeder but it did not work for whatever reason and I ended up just doing it the old fashioned way with the flexible tube immersed in brake fluid.

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The geyser is normal in most cases. It is the master cylinder returning fluid to the reservoir. Did you bench bleed the M/C before installation. They can be hard to bleed sometimes.

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I actually didn't bench bleed the master cylinder. The geyser happens when I depress the brake pedal though so there shouldn't be a geyser then, right?

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I had a similar problem a while back. I took a pump style oil can (clean, of course) and a hunk of vacuum tube and pressure bled them from the wheel cylinder nipples. Worked like a charm. Just watch the m/cyl reservoir it be sure it doesn't overflow. You may have to swipe Wifey's turkey baster to draw excess fluid out. Buy her a new one

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If you didn't bench bleed the M/C then your problem is air in the system. Watch a u tube video on it to see how much air there really is. Other guys can give you hints how to remove it as I have always done it on the bench as it is more than you would ever think. On the question of the so called geyser, when you do get the air out and go to bleed the rest of the system you will find out as you top off your M/C with fluid and don't put the cover back on loosely, fluid will be all over everything as it will geyser or shoot out of the reservoir ( been then, done that). Good luck.

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Yes. I suppose if you do have a bad unit it could also happen, but since you are on the third one (original plus two replacements) I believe your over thinking this. Get the air out, you've got to do that. If you have a booster the rod between the M/C and booster must be a adjusted correctly also.

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Yea thanks. I looked at it again today. I bled it again and noticed a few little air bubbles come out so you're probably right about air being in there. The pedal also seemed tighter after I did that although I think there still might be a few small air bubbles. I'm going to go through it again tomorrow and see how it feels.

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