leaking front master cylinder

[Hodag]

I have a problem, my front master cylinder is leaking. I'm not sure where, but when I ride, I notice drips from the master cylinder on my right glove box cover. Anyone gots any idea's?

[GSTom]

I have a problem, my front master cylinder is leaking. I'm not sure where, but when I ride, I notice drips from the master cylinder on my right glove box cover. Anyone gots any idea's?

Have you checked the rubber inner lid under the lid? a small tear or hole in it, or enlarged holes where the screws penetrate the rubber can allow brake fluid to get in between the lid and inner lid and seep out the screw holes, creating the drippage you describe. I have recently discovered a similar problem on my '88 K100LT. I haven't replaced the inner lid yet, but have kept the fluid level at the midpoint of the reservoir rather than near the top and the problem is under control. I'm confident that a new gasket will be the fix for me. HTH

[DonHamblin]

Originally Posted by Mark11LT
I have a problem, my front master cylinder is leaking. I'm not sure where, but when I ride, I notice drips from the master cylinder on my right glove box cover. Anyone gots any idea's?

Mark,

Sounds like it is the master cylinder itself, and judging from the age of the bike (I had to replace the master cylinder on my 93 K1100LT last spring) I wouldn't be surprised.

If you decide to replace it yourself, make sure that you also get all the "hardware" that might be "consummed" during the replacement. Then make sure that the system is properly bled (ABS makes it a bit more complicated, and loss of the front breaks can make for memorable / exciting riding).

Good luck,

Don Hamblin
Madison, Alabama
'93 K1100LT

[Jokar]

Been there too. My 95 R11GS developed a leak on the way to the Red River, NM rally in 2003. Doug (the wrench from Utah) replaced the piston assembly and all was well. Fast forward to Apr 2005 - it is leaking again. Time for a new master cylinder. Very possibly some wear/damage to the internals.

John Stombaugh
London.OH

[deilenberger]

Been there too. My 95 R11GS developed a leak on the way to the Red River, NM rally in 2003. Doug (the wrench from Utah) replaced the piston assembly and all was well. Fast forward to Apr 2005 - it is leaking again. Time for a new master cylinder. Very possibly some wear/damage to the internals.

John Stombaugh
London.OH

Yup - that's why BMW doesn't sell kits to rebuild the cylinder.

The usual cause of leakage is not following BMW's schedule of 2 year fluid flushes. Moisture gets into the fluid and starts corroding the bore of the cylinder. While new seals may stop it for a while - eventually it's gonna start leaking again as the new seals are damaged.

I gave up rebuilding hydraulic cylinders years ago after I had to keep rebuilding the same ones over and over.

A new master cylinder is expensive, but it is IMPORTANT, so don't put it off. Sooner or later one of the drips is going to land on your tank and start removing the paint.

Best,

[Hodag]

talked to the service guy today, he's orderring parts. he said I could easily rebuild it, but want to bring it in for a good shake down (its been a awhile since she has seen a computer). Plus figure its a good investment for future emergencies.
mark

[MCohen]

BMW also had problems with quality control on early 90s master cylinders. I replaced three at 16,000 mile intervals like clockwork on my '91 K100RS. Hopefully those problems are behind them and your master cylinder just wore out. ;)

Michael

[Bruce_C]

There is one on eBay right now.

[Hodag]

There is one on eBay right now.


all over it,
service guy at the shop says no rebuilding it. Need a new one.

[Gnome]

I've had the same problem. I have a 1987 K100 RS, and was going to ride down to Atlanta last month and added some break fluid. Ever since the master cylinder has leaked. A new one is in the works,a master cylinder that is. I tried to get a kit,but oh no,BMW sells you the whole thing.

[jdiaz]

I've had the same problem. I have a 1987 K100 RS, and was going to ride down to Atlanta last month and added some break fluid. Ever since the master cylinder has leaked. A new one is in the works,a master cylinder that is. I tried to get a kit,but oh no,BMW sells you the whole thing.
Um, its 18-years old. I think you got your money's worth.

[Gnome]

Thanks for pointing that out friend.. :brow

[bjm]

What ever you end up doing make sure you don't put it off like I did. I recently took my tank bag off only to find a mist of brake fluid all over my tank. Needless to say I now have to get my tank repainted. OUCH!!! :cry

[Hodag]

dropped off today,
that blue SSSSSSSSSSSSSSS
sure did catch my eye though