Leaking lever - Shimano brakes M365

Question

i recently took my bike to the LBS for brake service. Everything was fine until i noticed that the right lever (back brake) was leaking.

Every time i press the lever, it sort of "burps" a bit of oil and makes... funny sounds. (seen in picture 2)

I tried un-tightening the top cap, which really helped a lot but im not sure about the origin of the problem.
I should note that when i took it to the LBS for bleeding, the pads were 80% worn. After i replaced them, the problem appeared (the mechanic said it's fine if you do that, but i doubt it). I should also note that i torture them a lot.

Nathan Knutson · Accepted Answer

The first thing to check is that the rubber gasket in the brake lever reservoir is fully intact and in place. They can get both torn and clamped out of position, and that would be consistent with having just been opened up for bleeding. Make sure the reservoir is turned horizontal when open so fluid can't spill out.

If it's leaking anywhere else, there's not much that can be done other than replace the lever.

Sergio Bike mechanic · Answer

You need cheking where is leaking oil. If leak master-cyclinder you most reassemble them. Very accuratelu clean in gasoline and assembke. Problem usually in small dirt between rubber gaskets and cyclinder. And remember what that sort of brakes used mineral oil. Dont DOT4 or 5 !!!!!

Answered by Sergio Bike mechanic on August 28, 2021

Leaking lever - Shimano brakes M365

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