Contaminated brake fluid.

Any suggestions as to how to best clean the lines out, barring complete replacement? I am afraid that there might be some water and or contaminant in the brake lines.

I am planning to rebuild the master cylinder.

After disassembly, may use common household rubbing alcohol as a cleaning agent to remove old brake fluid residue, water and general crud, when refurbishing brake master cylinders, caliper and lines. I use a hand-sprayer attached to a plastic bottle of alcohol, which works well for this application (and some other general cleaning chores), q-tips and a toothbrush.

Afterwards, blow parts dry with pressurized air, and should then behold clean dry pristine new-looking parts.
Inspect master cylinder bore for excessive pitting. Next, dampen master cylinder piston, cups and bore with new brake fluid just before careful reassembly. And may also dampen caliper piston with new brake fluid before reassembling caliper. Best to replace all rubber items with new parts.

Fill system with new brake fluid and bleed the brakes. After bleeding, any brake fluid spilled onto exterior of master cylinder or caliper may be rinsed off with the alcohol spray.

For general quick easy routine maintenance "flushing" the brakes with new fluid without requiring extensive bleeding afterwards -- suck out most of the old fluid from the master cylinder, but don't empty the reservoir (because emptying it allows air being drawn into the system). Then fill the reservoir with new fluid (okay to leave the top cover off to monitor the level and keep it filled to above empty), and carefully and slowly bleed in the usual manner until fluid emerging from the caliper bleeder screw changes in appearance from the old stuff to the new fluid.

Test brakes for proper operation before riding the bike.
(Don't laugh. Others have learned about this the hard way.)

Good Luck!

P.S. Would remove or use cover on fuel tank to protect from damage or spills.

I would use a pressure bleeder to pump about a half gallon of new brake fluid through the system. If that didn't clean it out, I would plan on total disassembly to determine which bits needed to be replaced. Ed

Thanks guys, I will get some rubbing alcohol so I will not have to break into my scotch bottles for cleaning the parts.

I will take the whole system apart, calipers too. It is a beautiful day and I want to get my hands dirty.

you might want to change over to dot5, its going to stirr up a hornets nest, but I think it is the best stuff for brakes, dosent attract water, will not eat the paint, has a higher boiling point, just a better mouse trap

You aren't going to have any water standing in the lines, water mixes real well with brake fluid and it don't separate out.

If you take one pint of water in a quart jar and add 1 pint of brake fluid, you will have less than 1 quart of liquid in the jar.
You wouldn't believe how many times I have won money from people cause they bet me I was wrong

damn steell, didnt know that, I knew it absorbed water but I would have figured the volume would have been greater than that

steell wrote:

You aren't going to have any water standing in the lines, water mixes real well with brake fluid and it don't separate out.

If you take one pint of water in a quart jar and add 1 pint of brake fluid, you will have less than 1 quart of liquid in the jar.
You wouldn't believe how many times I have won money from people cause they bet me I was wrong

Have always heard the standard (non-Dot5 silicone-based type) brake fluids readily absorbed moisture, but that Dot5 did not absorb moisture.

Am thinking to a certain extent, moisture absorption is a favorable characteristic to keep water from settling and standing inside the m/c and caliper (especially behind the piston area) and doing its corrosive thing. Periodic flushing of regular fluid serves to renew the water absorption ability. But with Dot5, though it doesn't absorb water, flushing would seem as much or more critical toward keeping any free standing moisture removed from the system.

Have heard that Dot5 is slightly more compressable than standard paint-eating brake fluid, but Dot5 may enjoy a highter permissible operating temperature (better under extreme performance/racing conditions).

Am currently using Dot3 (as printed on the mc/ covers), being careful about keeping it away from the paint, and getting along with it just fine with routine flushing.

Just my thoughts, and anxious to keep learning more.

Good Luck!

Sheesh Patton, I was just looking at a comparison chart of different type brake fluids the other day, and you just summarized the whole chart in one post!

I should have just waited

But no betting allowed with steell until first having a chance to put water and Dot5 in a bottle together and shake it real good to see what happens. :laugh:

Have already lost way too many bets. :ohmy:

Sweeeeeeet,

After working to remove that damn C clip for an hour and 15 minutes (no kidding here) I finally got it out, probably the first time it's been removed in its 30 year tenure.

Remove the calipers and lines to flush them out with denatured alcohol, clean stuff up, meticulously, put it back together, grin gleefully, pour in some fluid and whoa! Get the drip pan out again boyz, it was the wrong rebuild kit. Fluid flowing from the area around the lever mount.

Perhaps I got the single caliper B rebuild kit, instead of the C kit.

O.k. Brake fluid all over the place and no test drive tonight.....

I, awh hell, Patience is for suckers....

That always happens when using too much scotch for things other than parts cleaning. :lol: At four shots per hour, that's five shots to remove the C-clip. :laugh: Sounds about right.

But just to clarify, the caliper has no C-clip and is of course separate from the master-cylinder which does have a C-clip. So fluid leaking from the lever-mount area would be from the m/c (not the caliper, and likely unrelated to any problem with the caliper or any new rubber parts or other parts installed in the caliper).

Regarding the m/c, refurbishment usually entails replacing the rubber cups (often the pimary cup is a separate part, with the secondary cup being included as part of a new piston), and also replacing the cir-clip and rubber dust-cover. Leakage past the m/c secondary cup will exude from the m/c (out through and past the dust cover).

Regarding the caliper, leakage could be from brake line fitting, bleed screw, or faulty large rubber o-ring piston seal.

Although probably not applicable here, if equipped with the later tapezoidal shaped m/c (not the early barrel-reservoir style), there's an o-ring under the reservoir which may ultimately begin to leak, and a rubber gasket under the top cover which may have been pinched or torn or for some other reason failing to properly seal and thereby allowing fluid to leak from the top area of the m/c. The trapozoidal style m/c uses a nylon or plastic retainer in lieu of the dreaded cir-clip.

My next drink of Johnnie Walker Black on-the-rocks will be a toast in your honor.

Good luck with the repairs.