How to dissolve crystallised brake fluid

[JimBoUK]

Hi Guys,

I am refurbishing the front brakes on a GPZ1100B1.
The master cylinder was full of crystallised brake fluid.
I can easily get most of it out but cannot get into the space behind the viewing window where you see the brake fluid level

Is there anything I can soak it in to clean it up and dissolve the crud ?
I've tried an ultrasonic cleaner with degreasing fluid running at 80 degrees but it did not touch it.
I've googled how to get rid of it and the main suggestion is to use denatured alcohol which is basically methylated sprits. So I tried soaking it in meths and no joy.

Any ideas ?

Thanks

Jim

[Zedorset]

Would brake fluid dissolved it?

[Jerry]

Or maybe boiling water? Just guessing, never done it.

[Gavin]

My MK 2 had a similar problem, I stripped the front master cylinder down (piston out) and run it though my ultrasonic cleaner, then when dry the crystals had turned to dust, then blew it out with an air line, took a couple of goes mind you,
If it’s that bad it will be the same in the piston chamber, I ended up getting new piston kits as the rear was the same.
Could you buy a new sight glass