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05-26-2022, 04:47 PM
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#1 |
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Registered User
Join Date: Feb 2022
Location: Ottawa Ohio
Posts: 44
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Brake Fluid Leak
I have a 1970 CST10 with factory power brakes. Just finished the restoration, and noticed there is a small amount of brake fluid leaking between the master cylinder and brake booster. Fluid appears to be coming out of the bottom of the master cylinder and running down the brake booster. No fluid is leaking from the master cylinder cap. Brake seem to work fine except for this small leak between the master cylinder and brake booster. Do I need to replace the master cylinder, or both the master cylinder and brake booster? I see rock auto offers a master cylinder rebuild kit, but it cost almost as much as a brand new master cylinder. Thank you for your help.
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05-26-2022, 05:44 PM
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#2 |
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Who Changed This?
 
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,676
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Re: Brake Fluid Leak
The master is toast. You can rebuild it, but if it is too pitted, you'll need to replace it anyway. You'd have to look into the booster to see if it is OK, but you can buy the assembly reasonably priced.
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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05-27-2022, 02:27 PM
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#3 |
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Registered User
Join Date: Jun 2016
Location: Bremerton, WA
Posts: 171
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Re: Brake Fluid Leak
The master cylinder piston seal is done, and/or the bore is pitted. It is getting really hard to find rebuild kits for master cylinders. I would buy a rebuilt one, but don't trade your original in for a core until you get the new one working.
Brake fluid absorbs water from the air and since the brake booster is not sealed the brake fluid and moisture in the air will soon rust out your brake booster inside walls so replace this asap and flush out the existing brake fluid out of your booster.
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1969 Custom Camper C20; Factree Air, 350/TH400/Dana 70U with C30 wheel cylinders, Disk brakes, H4 conversion, headlight relay mod, 3G 135 amp alternator. 7500 GVW |
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05-28-2022, 08:52 AM
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#4 |
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Senior Member
Join Date: May 2006
Location: Philadelphia, Pa. 19454
Posts: 9,761
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Re: Brake Fluid Leak
I have anew, booster sitting here, if you need 1, you pay shipping, I'll post up picks
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Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim |
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