Master Cylinder Leak

[tgtaylor64]

Why does my M1009 master cylinder almost always have a small drop of brake fluid on the outside bottom? I had this issue with the old one and replaced it and still have the problem. Nothing seems to be coming from the rear where it bolts up; besides, if it did, it would have to run uphill due to the slight angle.

 

[cucvrus]

I think the power brake booster is the problem. I had this on a truck for a few years and replaced the warranted master cylinder several times because of the same issue leaking brake fluid. It turned out after I changed the booster the problem went away. And it was DOT 5 fluid that was leaking. Also make sure that is what you are seeing leaking. I am guessing brake booster. It worked for me twice. I hope that helps you out. Others may not agree but it is my guess from afar.