Master Cylinder leaking
Thread Starter
Racer
Joined: Apr 2000
Posts: 279
Likes: 0
From: MOONACHIE NJ
Master Cylinder leaking
HI Guy's,My master cylinder was leaking from the cover so I replaced the cover and the rubber gasket inside also the metal bails.Went for a ride today and checked when I came back and its still leaking.Dripping from the top of the cap and landing on the steering arm.Is it time for a new one?Thanks for your time.Frank>STW< :flag
Melting Slicks
Joined: Aug 2000
Posts: 2,310
Likes: 1
Re: Master Cylinder leaking (NJ74STINGRAY)
:confused: Not sure if I can do much but bring this TTT.
Has it always leaked?
Did you replace the cap with the same type that was on there (maybe it's the wrong cap -- if it has always leaked)?
The MC could be cracked, but I don't know that you'd be able to see that.
How's the pedal feel?
How high do you fill the reservoirs (I usually go 1/4" below the top)?
Has it always leaked?
Did you replace the cap with the same type that was on there (maybe it's the wrong cap -- if it has always leaked)?
The MC could be cracked, but I don't know that you'd be able to see that.
How's the pedal feel?
How high do you fill the reservoirs (I usually go 1/4" below the top)?
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Master Cylinder leaking (NJ74STINGRAY)
Did you replace the cover with one of those crome Mr. Gasket pieces? If so it could be your problem. The metal those covers are made of is thinner than the stock type and prone to flex out rather than clamp down and seal. Also make sure the sealing surface on the master cyl is totally clean and free of surface rust and dirt. I found that the bails on my cover were not holding the cover down tight enough. I folded over a small piece of paper and tucked it between the bail and cover to give a tighter seal against the master cyl. Bottom line is, it must be spotless clean for a good seal, as well as clamping down tight.
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Re: Master Cylinder leaking (Jvette73)
Just ran into this a few weeks ago on a 72 I was working on...
Master cylinders do not all require exactly the same dimension cover. There are variations. A generic "replacement" or chrome cover will not necessarily fit the master cylinder you currently have in the car. If you look closely, you might find that the cover does not (and cannot be forced) to fit tight against the master cylinder top sealing surface. The gap is almost impossible to detect, but will leak as you describe. Temporarily remove the rubber seal, and place the cover on the M/C. Look closely to see if it mates correctly (evenly & flush) with the top of the M/C.
On the 72 job, I pulled out an old OEM 1970 cover and it dropped right into place. The replacement chrome cover that was on the car was a mis-fit. The owner is a fairly good mechanic, and he missed it himself. I just happened to catch it. Just a possibility.
Tom
Master cylinders do not all require exactly the same dimension cover. There are variations. A generic "replacement" or chrome cover will not necessarily fit the master cylinder you currently have in the car. If you look closely, you might find that the cover does not (and cannot be forced) to fit tight against the master cylinder top sealing surface. The gap is almost impossible to detect, but will leak as you describe. Temporarily remove the rubber seal, and place the cover on the M/C. Look closely to see if it mates correctly (evenly & flush) with the top of the M/C.
On the 72 job, I pulled out an old OEM 1970 cover and it dropped right into place. The replacement chrome cover that was on the car was a mis-fit. The owner is a fairly good mechanic, and he missed it himself. I just happened to catch it. Just a possibility.
Tom
Thread Starter
Racer
Joined: Apr 2000
Posts: 279
Likes: 0
From: MOONACHIE NJ
Re: Master Cylinder leaking (Tom454)
HI,Thanks for the help guy's.The cover I put on is AC delco part and so is the bails and the gasket.THe brake pedal feels fine and I do have power brakes.I have checked for cracks and do not see any.WIll check for the gap in the cover.Thanks guy's,Frank
Race Director
Joined: Aug 1999
Posts: 18,126
Likes: 174
From: WI
Re: Master Cylinder leaking (NJ74STINGRAY)
Frank,
I had this problem with my racer after i put on a rebuilt MC. Take the bails (one at a time) and put both ends in a vice then take a hammer (honest) and slightly hit the center of the bail this will bend the center down just enough to "shorten" the bail and make more of a positive seal. ...redvetracr
I had this problem with my racer after i put on a rebuilt MC. Take the bails (one at a time) and put both ends in a vice then take a hammer (honest) and slightly hit the center of the bail this will bend the center down just enough to "shorten" the bail and make more of a positive seal. ...redvetracr
