About 3 month ago i mounted another master brakecylinder from a Sierra.
The one i mounted first was leaking.
Now the next one i bought is leaking again.
Is it better to buy a new master cylinder or was it just bad luck.
The car isn't readlegal yet so there hasn't been much breaking with the car


Any advice please ?

Thanks, Marco

Never undone a master cylinder but does it have a gasket?

Take them both to bits and see if it is the seals or the barrel. It is always a risk with second and parts snf brake component seals do not like being left dry for long periods the seals can harden. It is always an option to renew seals if the barrels and pistons are perfect, if not then get a new cylinder.

Caber

As above, but you might also think about using a dust seal on the push rod, as the Sierra cylinder does not have one (the servo covered it). So you might be getting grit/dirt into the cylinder..

My old sierra cylinder was leaking after sitting around for a while of the sierra as well..

Cheers

Dan

[Edited on 30/1/08 by Bluemoon]

If they've been off the car for a while, they tend to dry out and the seals become brittle and crack when pressed back into service. I'd go for a rebuild kit comprising all the seals you need, I generally build them up using a dab of 'red hydraulic' grease, it is very rare any of the metal parts wear, but look out for rust if its been stored carelessly.
Rgds.
Pete.

fitting a brake component of unknown serviceablilty is not the best move.

if the fluid is allowed to run dry or not replaced, moisture can rust the insides.

At the very least you should take it apart and clean it out and look at the condition of the seals and the bore. Maybe you can make one good 'un from the two bad ones although I'd recommend either buying a new seal kit if the bore is fine buying a new master.

Yes, that may be expensive but it works out a lot cheaper than funeral or hospital bills and/or the cost to rebuilt the front part of your car.

Where is it leaking from? Is it leaking out of the barrel where the push rod goes in or is it leaking from where the reservoir joins?

If its the latter did you replace the reservoir or just the master?

I had this fault on my mx5 a while ago, replaced the two rubber o-seals for the reservoir and all was sorted.

HTH


David

Last time I looked for a Sierra recon kit a reconded unit was about the same price as the seals and piston.

[Edited on 30/1/08 by Schrodinger]

Thanks for all the reply's.
I just ordered a new one, better to play safe with this like you said.
It was € 80,- and a can get it tomorow.

Thanks, Marco