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Leaking brake Fluid

G

gltee_9

Member
I'm leaking brake fluid at my master cylinder for the front brakes. Everything is tightened up, took the lever off and it seems to be coming from a "boot" on the small plunger inside where the lever presses against. Is that possible or is there another area inside it could be coming from. I have a 99 FXD...Thanks
 
Sounds like it is time for a master cylinder rebuild or a new m/c cylinder. The brake fluid is bypassing the seals of the m/c and leaking past the boot.
 
Just one note, do NOT use cleaning fluids of any kind to clean, repair or rebuild brake master/cylinder...This is one of the few times water is used to rough clean everything, and use compressed air to blow dry all passages. Now flush everything with brake fluid only. Use fresh brake fluid (no old brake fluid, water or trapped air bubbles AND be sure it is the right type...DOT 3,4 & 5.1 are Ethylene Glycol based, DOT 5 is Silicone based and neither is compatible with the other or petroleum/mineral oil based solvents PERIOD. It will swell rubber, neoprene parts, damaging anything it contacts and cause immediate or worse latent brake failure.

Do not use shop towels that could deposit lint, dust or debris...the tolerances in the M/C are 1/10,000ths, similar to hydraulic lifters that use a few microns lubrication film...any more and fluid leaks past. Clean area and hands using plenty of brake fluid to flush, clean and lube, wet seals with brake fluid and immediately assemble parts.
 
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Thanks for the advise. I'm going to buy a rebuild kit and give it a shot, never done one before but it's all about learning new things when working on a Harley is the way I look at it. I've been told it's not too hard so should be a good time. Thanks again.
 
once you get the master cylinder off you may find that the piston doesn't just fall out of the master cylinder as you try and take it all apart
place master cylinder on workbench with with banjo fitting end up place suitably sized ball end Allen key in the banjo end of master cylinder and tap with rubber mallet should force piston out without causing damage

Brian
 
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