DaveC6970 Posted July 7, 2022 Share Posted July 7, 2022 Hello, I have a brake issue I was hoping someone may have some experience/insight with, I searched the forum and my service manual and haven’t had any luck. When I apply the brakes on my 63 everything works normally and I initially have plenty of boosted brake. Once slowed the pedal will quickly drop away from my foot and the car begins to roll, so I panic jam the pedal and the car stops again. I assumed since I was losing boost it was a vacuum issue so, based on some forum answers, I replaced the vacuum hoses from the manifold to the brake booster and one from the reservoir to booster. This did not help but I’ll keep checking for vacuum leaks. Maybe an internal booster leak? Would a bad check valve on the manifold line cause an issue like this? Also, I did check for brake fluid leaks and could not find any, but this might be a master cylinder issue? I have zero experience with a bad master cylinder so I wouldn’t know. Any ideas or advice is appreciated, Thanks! Dave Link to comment Share on other sites More sharing options...
EmTee Posted July 7, 2022 Share Posted July 7, 2022 It sounds like a bad master cylinder. It is leaking internally and I'll bet you find some fluid leaking past the seal where it interfaces with the push rod. Probably dribbling down the front of the booster can... 3 Link to comment Share on other sites More sharing options...
RivNut Posted July 7, 2022 Share Posted July 7, 2022 Besides what EmTee suggested, check the vacuum canister and see if there’s fluid in it. 2 Link to comment Share on other sites More sharing options...
DaveC6970 Posted July 7, 2022 Author Share Posted July 7, 2022 Thanks guys, now I have some new leads to check! Link to comment Share on other sites More sharing options...
tenugent Posted July 7, 2022 Share Posted July 7, 2022 As Ed said,my booster was bad and I found quite alot of fluid in my canaster Link to comment Share on other sites More sharing options...
EmTee Posted July 7, 2022 Share Posted July 7, 2022 While you're working on the hydraulics it would be a good time to check the wheel cylinders and replace the brake hoses if you haven't previously. 1 Link to comment Share on other sites More sharing options...
telriv Posted July 7, 2022 Share Posted July 7, 2022 IF there is brake fluid in the booster it will HAVE to come off & be rebuilt also along with the bad master cylinder. Tom T. Link to comment Share on other sites More sharing options...
XframeFX Posted July 7, 2022 Share Posted July 7, 2022 12 hours ago, EmTee said: While you're working on the hydraulics it would be a good time to check the wheel cylinders and replace the brake hoses if you haven't previously. 7 hours ago, telriv said: IF there is brake fluid in the booster it will HAVE to come off & be rebuilt also along with the bad master cylinder. Doing this right now. Don't bother choosing between AC Delco Professional, Raybestos, Centric . . . THEY ARE ALL MADE IN CHINA! If Sunsong brand is available, go for it. Lowest price. There is a warning to straighten and flex hoses prior to install, what? All components have to conform to SAE and DOT specs. But, I can't help to think brake parts I purchased back in the day, made in USA, are better. Link to comment Share on other sites More sharing options...
EmTee Posted July 8, 2022 Share Posted July 8, 2022 1 hour ago, XframeFX said: There is a warning to straighten and flex hoses prior to install, what? I recall a similar instruction when I replaced the hoses on my Riviera with ones I bought from NAPA. The caution was to ensure they were not twisted when installed. In other words, the ribs on the jacket should not be twisted when the ends are connected to the hardware. 1 Link to comment Share on other sites More sharing options...
telriv Posted July 8, 2022 Share Posted July 8, 2022 What EmTee is saying is correct. NO twists in the hose after installation. Tom T. 2 Link to comment Share on other sites More sharing options...
Electra63 Posted July 14, 2022 Share Posted July 14, 2022 Hello everyone. This is a timely post for a similar issue I'm experiencing ! I believe I also have a bad/leaking booster. My symptom is that when I pump the brakes, a few seconds later (perhaps 5-6 seconds), the brake lights come back on. I replaced the pressure switch on the front of the master cylinder but no change. I'm thinking there is a slow leak in the booster thats affecting the pressure on the front end of the master cylinder. My booster unit looks original and I'd like to replace it but I'm having a problem finding one that is compatible for my '63 Electra 225.... Can someone offer my a clue as to how to search for a suitable/compatible one? I' m assuming its a pretty standard GM unit across a few models so should be easy-ish to find? thanks ! Link to comment Share on other sites More sharing options...
avgwarhawk Posted July 14, 2022 Share Posted July 14, 2022 (edited) 21 minutes ago, Electra63 said: Hello everyone. This is a timely post for a similar issue I'm experiencing ! I believe I also have a bad/leaking booster. My symptom is that when I pump the brakes, a few seconds later (perhaps 5-6 seconds), the brake lights come back on. I replaced the pressure switch on the front of the master cylinder but no change. I'm thinking there is a slow leak in the booster thats affecting the pressure on the front end of the master cylinder. My booster unit looks original and I'd like to replace it but I'm having a problem finding one that is compatible for my '63 Electra 225.... Can someone offer my a clue as to how to search for a suitable/compatible one? I' m assuming its a pretty standard GM unit across a few models so should be easy-ish to find? thanks ! Booster Dewey. https://boosterdeweyexchange.com They had one for my 60 Electra ready to go. Got it in 4 days and my Electra was back on the road. Edited July 14, 2022 by avgwarhawk (see edit history) Link to comment Share on other sites More sharing options...
63 nut Posted July 15, 2022 Share Posted July 15, 2022 I have a question on brakes. My pedal only goes down about a 1/4 inch and is hard but the car does not stop that quick. Could my booster also be filling with fluid. Link to comment Share on other sites More sharing options...
avgwarhawk Posted July 15, 2022 Share Posted July 15, 2022 (edited) 7 minutes ago, 63 nut said: I have a question on brakes. My pedal only goes down about a 1/4 inch and is hard but the car does not stop that quick. Could my booster also be filling with fluid. If your Buick has the same booster as my 60 Electra(I believe it does), yes, it can fill with brake fluid. As a result, the rubber products inside the booster swell. The booster does some funky things with swollen rubber products inside. In my case, the pedal when pressed would take off towards the floor boards all by itself!!!! All 4 wheels would lock. The only way I could release the brakes was removing the vacuum hose to the booster. Booster Dewey had a replacement for me. I shipped my core for the next guy who has a booster issue. I also replaced the master cylinder because it was the culprit leaking into the booster. EDIT: What I did to assure the booster was the issue was leave the vacuum hose off effectively making the brakes manual. I drove the Buick and needed some leg muscle to stop the car but it did stop and the pedal did not go to floor by itself thus locking up all 4 wheels. Edited July 15, 2022 by avgwarhawk (see edit history) Link to comment Share on other sites More sharing options...
EmTee Posted July 15, 2022 Share Posted July 15, 2022 4 hours ago, 63 nut said: My pedal only goes down about a 1/4 inch and is hard but the car does not stop that quick. How old are your brake hoses? Link to comment Share on other sites More sharing options...
avgwarhawk Posted July 15, 2022 Share Posted July 15, 2022 18 minutes ago, EmTee said: How old are your brake hoses? Darn fine question. Link to comment Share on other sites More sharing options...
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