1977 Chevrolet Truck Master cylinder

Tiny
GEORGE THRONE
  • MEMBER
  • 1977 CHEVROLET TRUCK
  • 5.2L
  • V8
  • 4WD
  • MANUAL
  • 200 MILES
Master cylinder is leaking between it and the vacuum booster. This is a new (not a reman.) Master cylinder. This is the third one that I have used at all three leaked in the same place. I do not know if there is supposed to be some kind of a gasket between the master cylinder and the vacuum booster. If not, I sure would like to know what else to look for. Any and all help you could give me on this matter would be greatly appreciated.
Monday, June 1st, 2015 AT 6:01 AM

6 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Are you sure it' snot residual brake fluid in booster? There is non vacuum on that side of booster. If there is the booster needs a new diaphragm. Is the fluid level actually going down in master?If it is the same type of master try another supplier as so much crap comes from china so that may be the problem.
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Monday, June 1st, 2015 AT 6:31 AM
Tiny
GEORGE THRONE
  • MEMBER
  • 11 POSTS
Yes, the master cylinder is definitely losing fluid. As I said, this being the third one with the problem at not changing I wondered if it's possible that could be something with the vacuum booster. I never ran into this before nor has anyone I have spoken with. Would having be wrong booster on the vehicle by any chance cause that? As I said this being the third one and the first two being rebuilt and is the last one is supposedly from the factory. And the problem still exists. Once again if anybody can help me with this problem I would greatly appreciate it. I thank you for your help.
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Monday, June 1st, 2015 AT 7:16 AM
Tiny
GEORGE THRONE
  • MEMBER
  • 11 POSTS
On that pickup there is 200,000
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Monday, June 1st, 2015 AT 7:16 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
The only way the booster could do anything is suck fluid from the master which I doubt I have never seen that. Like I said try another supplier as the on you are getting may just be poor quality.
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Monday, June 1st, 2015 AT 9:50 AM
Tiny
GEORGE THRONE
  • MEMBER
  • 11 POSTS
I want to thank you guys for once again for trying to help me. I will tell my buddy that he has to buy from a reputable dealer. I believe he's willing to try anything once. Once again thank you very much for the help.
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Monday, June 1st, 2015 AT 3:33 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Wel it's ironic as I've done this for 50 yrs and have never seen a New master do that bu the junk that comes from china hard telling. Rebuilt unit I have seen but not new.
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Monday, June 1st, 2015 AT 4:07 PM

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