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#1
07-08-2023, 06:52 PM
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Small brake fluid leak in between my master cylinder and booster on my 1979 TA/SE
I was getting ready to drive my car (1979 TA/SE 4spd) and decided to check my brake fluid since I dont drive the car very often. I noticed that the rear bowl of the master cylinder was very low. I did some more looking around and I noticed that there is a small leak between the master cylinder and power brake booster.
Anybody know what might cause this? Would it be a bad master cylinder or something wrong with the booster. Approximately 8 years ago I installed a new master cylinder and had the brake booster rebuilt by Booster Dewey. I know all parts fail at some point but I just want to know if somebody else had something like this happen and what the cause of it was so i can fix it. Any input is welcome and thanks! |
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#2
07-08-2023, 07:07 PM
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If the back of the master is leaking, just replace it. Unless there is a kit to replace the seals. The rear wheel cylinders can leak also. Brake fluid rinses off with water. I dont think Brake Fluid in the booster actually hurts anything.
__________________
1968 Firebird 400 RAII M21, 3.31 12 bolt, Mayfair Maize. 1977 Trans Am W72 400, TH350, 3.23 T Top Everyone you will ever meet knows something you don't. Bill Nye. |
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#3
07-08-2023, 07:20 PM
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Replace the master!
__________________
The difference between inlaws and outlaws? Outlaws are wanted |
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#4
07-08-2023, 07:48 PM
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The master is leaking.
__________________
"Those poor souls have made the fatal mistake of surrounding us. Now we can fire in any direction" 1970 Trans Am RAIII 4 speed 1971 Trans Am 5.3 LM7 1977 Trans Am W72 Y82 1987 Grand National |
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#5
07-08-2023, 07:54 PM
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The leaking brake fluid will eventually kill the diaphragm in the booster.
__________________
1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... 
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#6
07-08-2023, 10:44 PM
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I will replace the master cylinder then. Thanks guys!
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#7
07-09-2023, 06:23 AM
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Before you go thru all the effort to replace the master first try flushing / bleeding the whole system out.
Brake fluid should not have a light brown tint to it. Many times I have had a small leak like that and it was due to very fine rust particles build up in the fluid, and there’s no type of hydraulic seal on the planet that will seal on grit. Besides your going to basically ( or you should) flush the whole system out if indeed it does come down to needing a new master, and the cost of going thru one or two more can’s of brake fluid is small. Also while your at it if both of your front brake hoses are original ( near 50 years old ! ) and so is your rear one likely, now is the time to change them out. When they collapse on the inside ( which you can’t see) it takes more pedal pressure to apply the brakes, and it can also allow the brakes to hang up and then if nothing else your chewing up pads and brake shoes very fast.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! Last edited by steve25; 07-09-2023 at 06:30 AM. |
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#8
07-09-2023, 09:29 AM
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My master went the same way. Just replace the dumb thing lol
__________________
1979 Trans Am W72 400/4-Speed WS6 - Starlight Black Hardtop  |
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#9
07-09-2023, 10:10 AM
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Quote:
__________________
1968 Firebird 400 RAII M21, 3.31 12 bolt, Mayfair Maize. 1977 Trans Am W72 400, TH350, 3.23 T Top Everyone you will ever meet knows something you don't. Bill Nye. |
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#10
07-09-2023, 06:36 PM
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Quote:
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Jeff 
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#11
07-10-2023, 07:12 PM
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That was my thoughts also. Last one I had leak fluid into the booster, I used a vacuum hose connected from the intake manifold down the master hole to suck up any fluid. Then I poured some rubbing alcohol down there and sucked it out, hoping to get a majority of fluid out. Then connected everything normally. I figured the alcohol under engine vacuum, would evaporate out pretty well.
__________________
1968 Firebird 400 RAII M21, 3.31 12 bolt, Mayfair Maize. 1977 Trans Am W72 400, TH350, 3.23 T Top Everyone you will ever meet knows something you don't. Bill Nye. |
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#12
07-11-2023, 09:27 AM
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Brake fluid absorbs moisture causing humidity to start corroding the metal and then leak.
My 65 GTO and 64 Impala projects have rust holes below the MC in the firewall from leaking.
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
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#13
07-11-2023, 11:21 AM
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I currently have the exact same issue on my '74. Where would one get a replacement master they can count on in this age?
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