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Old 03-07-2011, 02:06 PM   #1
travisfraughton
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Cool Master Cylinder seal

well i replaced the master cylinder on my 70 lwb last year, and it seems to work fine, but whenever I pop the hood the master cylinder looks wet/covered in fluid. it seems like I am losing fluid and when i check it it is frequently low.
I'm wondering if it's probably just that the cap is not being held down tight enough/ not sealing to the body of the mc. anyone else ever had this?
I'm thinking of just trying to bend the little metal retainer that goes on top of the mc cover, or something to get a tighter fit. I'd really hate to think i'd have to replace the mc with it being practically brand new.
anyone ever had just the top cover go bad?
can you buy just the top cover?
or is it something to do with the metal retainer, (it doesn't seem loose to me at all.)

Thanks for any experiences
Travis.
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Old 03-07-2011, 02:59 PM   #2
cdowns
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Re: Master Cylinder seal

have you inspected the rubber gasket real good?is it a factory MC cover?aftermarkets especially chrome are quite unreliable check the sealing surface on the MC for hilospots

the wire holddown should b available autoparts store help section just make sure you get the right one
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Old 03-07-2011, 04:02 PM   #3
travisfraughton
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Re: Master Cylinder seal

it's not a chrome cover,
It is just the part that i ordered at autozone near my house.
I will inspect the little rubber gasket that's in the mc cover later today to double check, but previously i didn't see anything wrong with it.
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Old 03-07-2011, 08:19 PM   #4
697498chevy
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Re: Master Cylinder seal

Be interested in a fix . My '69 has the same problem .It's also fairly new .
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Old 03-07-2011, 11:50 PM   #5
dmack91
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Re: Master Cylinder seal

Same on my 68. I went to NAPA and ordered a new gasket. Neither of the ones they list fit. The closest was about 1/8" too wide all the way around. I ended up buying it and trimming it down, but still have the same problem.
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Old 03-08-2011, 02:06 PM   #6
1-PU70
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Re: Master Cylinder seal

If you pull the cap off and look at the mating surface of the master you will notice it is cast and has small indentations. This is how I fix them when they leak. Remove most of the brake fluid from the master. The wifes turkey baster works good. Then fill the master with rages. Then with a pice of 2x4 and sone sandpaper start to sand the top lip of the master till most of the casting pits are gone. Then you are good to go. I like to do this before instalation. Then I just turn it up side down on the table with a pice of sand paper on the table and start sanding. And yess you can tightin the bailing strapes. Good luck.
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Old 03-08-2011, 02:28 PM   #7
custom1970
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Re: Master Cylinder seal

I also had the same problem. I was able to stop it from leaking by removing the rubber seal, placing a piece of cork gasket material inside and then replacing the rubber seal. It's a little tight getting on but it seems to have stopped the leaking.
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Old 03-09-2011, 07:40 PM   #8
697498chevy
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Re: Master Cylinder seal

Thanks !
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