leaking hydraulic brake calliper

[alecstilleyedye]

my shimano 105 rear brake seems to be leaking fluid. any idea:

• what's causing it
• how to fix it

I've checked for loose nuts etc. and the brake works but with a lot of travel.

thanks in advance

 

[I like Skol]

my shimano 105 rear brake seems to be leaking fluid. any idea:

• what's causing it
• how to fix it

I've checked for loose nuts etc. and the brake works but with a lot of travel.

thanks in advance

Bin the caliper, fit a new one, get on with your life.

In an ideal world you would be able to buy new seals from Shimano to repair this but they (Shimano) do not work like this and I'm pretty sure that while some surprising things are available as spare parts from Shimano, the caliper seals are not.

I have had a similar problem with some XT calipers in the past. Couldn't work out why my pads we're getting contaminated, brakes stayed firm but lost friction/bite. Eventually noticed the affected caliper was slightly darker than the other. Not wet/damp, just subtley darker due to a very slight oil weep from one of the pistons. Strangely wasn't letting air in.

 

[13 rider]

I would guess the seal round the piston . Don't think it's a replaceable part new caliper time
Edit
Beat to it while typing

 

[alecstilleyedye]

I think it might be down to either:

• using some fluid (bought online with, but not part of a Shimano bleed kit) that has blown the seals
• my own tommy coopering trying to fit new pads and jam the wheel in

I've managed to source a new pair online in case it's a case of the former as the front calliper will surely go the same way if so…

will let lbs deal with flushing and fitting new calliper.

 

[Ming the Merciless]

You seem a bit vague on the fluid you bought. What exactly did you buy? It should have been mineral oil…

 

[alecstilleyedye]

it was a bottle of red stuff that was said to be mineral oil:

https://www.ebay.co.uk/itm/262088716087

 

[Ming the Merciless]

it was a bottle of red stuff that was said to be mineral oil:

https://www.ebay.co.uk/itm/262088716087

Looks right colour for Shimano mineral oil at least 😃

 

[alecstilleyedye]

the front seems unaffected. the brakes only had a small amount of the liquid added anyway; some in the reservoir on the shifter and pulling the lever to remove air, so a contamination rather than wholesale flush through…

 

[alecstilleyedye]

Looks right colour for Shimano mineral oil at least 😃

it was rather more runny than I imagined…

 

[si_c]

it was rather more runny than I imagined…

It is very fluid, similar to baby oil. I doubt it is the oil that had caused a problem with the seals, more likely you'd done a poor bleed. I'd suggest draining the system entirely and then push some new fluid all the way through.

 

[Milkfloat]

I have had problems with 105 callipers. One, like your where the seals just seem to leak no matter what I tried, another where the screw holding the pads in was totally seized, this screw is made of cheese and not even hard cheese, more like cream cheese. In both cases I just bought new callipers as there was nothing I could do to rescue them, even with disassembly.

 

[alecstilleyedye]

my Shimano 105 brake calliper needs replacing. the part arrives today. is it as simple a job as unscrewing the old calliper, screwing the new one on and adding brake fluid?

 

[T4tomo]

View: https://www.youtube.com/watch?v=jFq7TbtgrD8

 

[fossyant]

You'll need to bleed it properly.

 

[alecstilleyedye]

You'll need to bleed it properly.

I think it's pretty empty already…