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MG MGB Technical - Leaky Master Cylinder

I have a new (not rebuilt) master cylinder (single-line, metal reservoir) in my '67 MGB GT. After only a few months of using it as a daily driver (all of 5 miles a day) it has developed a slow leak, dripping perhaps half a teaspoon a day. The area around the banjo union is dry, and nothing is seeping past the seals, which only leaves the resorvoir as the prime suspect. I can't unfortunately see, or get a hand on it to feel, where the reservoir leaking. Are there replacable seals between the cylinder and reservoir, or am I going to have to buy yet another new part to replace a substandard new part I've just installed?

~Jerry
Jerry Causey

I'm fairly sure the reservoir is welded to the cylinder , can't you get it changed under warranty ?
I have a dentists mirror on an extending stick (like a car aerial). Which is useful for this sort of inspection , I got it at a market for about 50p.
S Best

Jerry-

I had the same problem on a 'new' MC. The leak turned out to be the cap sealing. Where the resevoir is molded together the 'join' was not totally flat across which left a small 'divit' that the rubber seal did not seal. Hence a slow leak. Ended up replacing the whole unit and got a good one that doesn't leak. Could be your problem.
Sam

Sorry Jerry, I just reread your post and see you have a metal m/c. Mine is the dual plastic one.
I'd make sure the actuator rod is aligned and not at an angle. I had one on my clutch m/c that was at an angle and it was making the internal plunger scrape the side of the bore. Wasn't long till it started to leak.
Sam

This thread was discussed between 21/05/2004 and 22/05/2004

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