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Seized master cylind


Paulfc
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I'm in the process of restoring my car which has been standing warm and dry for 20 years plus. I've started to strip the master cylinders, which are off the car, and found they're in a poor state with aged, coagulated fluid. Consequently the "internals" won't budge. I've cleaned out as much crud as I can and put fresh fluid into the reservoir in the hope it'll seep through the bore and maybe ease things. If anyone has any other ideas as to how I might able to " get the insides out" I'll be very grateful.

Paul

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I have snapped master cylinders trying to get seized pistons out. And on ones where they have eventually moved, the bores are not good enough to use. As the pistons start to move, any grot will score the bores. Unless you are luckier than me. So quite possible.

So as above, it is probably best to bite the bullet and buy new. Or even get yours resleeved in stainless (more expensive, but I expect a longer lived solution) and I expect a refurbisher has a gixmo for pumping the piston out. I have tried an airline (hopeless, not enough pressure at 140psi) but linking another master cylinder has worked. But as above, to no real advantage. Also heard of people using a grease gun, but you need the right threads etc to fit it to the master cylinder.

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Can be slightly different dia to the 0.7 or 0.625" as specified but if thats not overlly concerning look on ebay etc for landrover nearly eqivalent units at sub £20  the reservior wont be angled but thats not a real problem unless you over fill

Other Places like merlin motor sport or car builder solutions all have master clys and decent sized clear  reservoirs you can fit to them often cheaper than angled replacements which comand silly prices

The pushrod on these often needs your original  so dont bin them.

Do a search before you jump into deep pocket original looking replacements 

Pete

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Pete,Andrew,

Thanks for the sound advice. I've actually managed to rescue the clutch MC with lots of fluid and then working the piston repeatedly, so I guess may not have been so much seized as just full of congealed crud. Brake MC tomorrow. 

Paul

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Boil them in water; the heat expands the metal sufficiently, or softens the rubber and crud, to free the internals without doing any damage in itself, and you can then gently pump the bits out with grease or air. You'll need a complete refurbishment after that, though. 

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I had a similar issue and used a grease gun connected to the cylinder - When freed the piston will go off like a gun as the pressure of the gun is very high much more than a compressor - Then its a case of cleaning out the grease 

Paul 

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