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MG MGA - Leaking Master Cylinder

I have a very slight leak from the twin master cylinder on my MGA Mk2 Coupe. I have ordered a repair kit from the MGOC. Do I need to remove the master cylinder to fit the new seals or can I just release the pedal connection and take out the pushrod etc in situ ? Any tips or problems I might encounter would be helpful ie Do I need to drain the MC before starting?
P D Camp


Are you using silicon or ordinary brake fluid. Doing the job in situ increases the risk of some fluid spillage. If using ordinary fluid it could damage your paintwork.

I usually remove my MC but it can be done in place. After disconnecting the rods you could just remove the MC front retaining bolt allowing you to tilt the MC backwards a bit, reducing spillage and aiding access.

Additionally, I empty the MC with a syringe, pipette or plastic tube (suck fluid out - health & safety look the other way!) before doing any maintenance.

Steve Gyles

Thanks Steve
I have quite a good syringe to get most of the fluid out- Its Dot 4 fluid-Appreciate the tip re releasing front bolt I would not have thought of that
P D Camp

Hi Paul, I tried to do mine in situ a couple of years ago. Initially I managed to remove the pistons without too much trouble - after first getting as much fluid out as possible out as Steve describes. When I reassembled it all I could not get the pistons to move in the cylinders. I eventually had to dismantle it all again and remove the master cylinder to get the pistons out again. The new seal was such a tight fit that the piston was stuck on the bore - I had to gradually work the piston in the bore backwards and forwards a few times to make it free enough to operate properly - and yes I did get the fluid all over the bulkhead taking a layer of paint off - make sure you have lots of cloths around the master cylinder to catch any spilled fluid. I think this problem has been discussed at length a couple of times before - check the archive - good luck - cheers Cam
Cam Cunningham

Paul, Have a look at the photo - I did the job recently - only removed a small volume of the fluid, replaced the seals and managed to keep the fluid seal - no need to bleed the system. A great saving in time and effort. Just bend the pipes slightly to angle the MC enough to prevent spills. It worked!! Just in case of a spill I placed damp sheets but managed without any trouble.

BM Gannon

Thanks Barry & Cam
Your thoughts have given me more confidence to tackle this job
P D Camp

This thread was discussed on 27/10/2009

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This thread is from the archive. The Live MG MGA BBS is active now.