Front Brake Master Cylinder Leaking, 89 K75C

Fluid is dripping out of the master cylinder assembly. In conversation with the parts desk at a SoCal BMW dealership, it was their opinion that it was like to be the master cylinder that was leaking and not the o-ring below the resevoir.

I have front dual discs, rear drum, no ABS.

Have any of you experienced this? Can the master cylinder be "tuned up?" I don't like the north of $200 price tag on a new master cylinder.

I have the manual that describes and shows the disassembly and reasssembly of the master cylinder, but it doesn't talk about whether you can stop a leak or any tune up type procedure.

Thanks in advance!

You probably just need a rebuild. Hopefully the bore isn't damaged. I used one of these and it's lasted longer than the original...$45 http://www.beemerboneyard.com/32722302356.html

PS_if you order online from Beemerboneyard enter BMWMOA under "source code" in the "other information" box on the shipping and billing page for a 10% discount.

35634 said:

You probably just need a rebuild. Hopefully the bore isn't damaged. I used one of these and it's lasted longer than the original...$45 http://www.beemerboneyard.com/32722302356.html

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Thanks! Perfect.

I bought a brand new master cylinder in January and I continue to get weeping of hydraulic fluid around the hollow bolt (banjo joint) crush washers. So purchasing another master cylinder is not always the solution to a problem.

What kind of washers of you using: copper or aluminium?

You may want to consider a new hollow bolt and/or new washers.

My master cylinder was leaking and it turned out the banjo nut on the brake line needed tightened. Check that first. I am amazed my 23 year old seals are still good!

Scott

TinyTrains said:

My master cylinder was leaking and it turned out the banjo nut on the brake line needed tightened. Check that first. I am amazed my 23 year old seals are still good!

Scott

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It isn't the banjo bolt or crush washers, it is leaking out of the handle area. A new master cylinder rebuild kit arrives today. I will let you all know how it goes.

Got the rebuild kit from Beemer Boneyard, easy peasy replacement. Bled the brakes with my Mighty-Vac speed bleed and jumped on the bike and made a run to San Francisco yesterday from LA. Nice to have front brakes!