Shimano m615 lever leaking

bobbydigital

During/after bleeding this brake I noticed mineral oil leaking from underneath, dripping down on the lever pivot.
I read if the brake has too much fluid in it it will purge itself but I wanted some confirmation?

It was fine for a long time, pads got low, as I switched to new pads and pushed the pistons back in, the fluid started to leak out. Initially it was bled with a bleed block so the pistons would have been flush anyway so not too sure what's going on.


Where that pivot it, shiny due to oil there.

02gf74

Bobbydigital wrote:

I read if the brake has too much fluid in it it will purge itself but I wanted some confirmation?

Where did you read that?

I've used many models of shimano brake and never had that, nor indeed on other brands, avid, sram, formula, magura.

Some will have a vent hole (formula) but not had brake fluid leaks.

bobbydigital

It was on singletrackworld.

Apparently if they are overfilled there's a whole inside near the plastic cap that purges away excess fluid but I've not had the issue on the other m615.

I bled them previously using the push from caliper method and wondered if that might have caused it, even though I believe it's the recommended way rather than bleeding downward in to the caliper.
The brake seems to function fine afterward and doesn't lose any more fluid.

02gf74

see here: http://www.epicbleedsolutions.com/blog/ ... ini-bleed/

The mini bleed works by essentially over-filling the system with brake fluid. As your brake pads wear the calliper pistons move outwards to compensate for the reduction in pad material. This creates space inside the brake system for additional brake fluid.
By adding extra brake fluid the point at which the pads contact the rotor happens much sooner in the lever stroke giving you great feeling brakes.
What's the Catch?
There's only one and it's pretty small. As you've previously over-filled the system with fluid you will find it difficult, if not impossible, to push back the calliper pistons to make enough space to accommodate those shiny new brake pads.
Luckily the solution is simple. By removing the lever bleed port screw the pistons will push back easily as the extra fluid can now escape - this means you'll want to catch the overspill with a paper towel or similar.

bobbydigital

I just think it's broken, constantly leaking when bleeding. Never ending cycle of air bubbles with the quick bleed so switching to a slx m675 which come up solid and no leaks.