Brake fluid coming out of pistons  

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gobstopper
(@gobstopper)
Active Member

Just tried to bleed my brakes for the first time and it managed to fail miserably as I now have fluid spewing out of the pistons when the brake lever is depressed. I'm not too sure where I went wrong here as I followed the instructions and used a bleed block etc. Is my brake buggered? has the seal on the piston gone? Any help would be appreciated. Thanks

This topic was modified 6 months ago by gobstopper
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Posted : 27/08/2018 9:31 pm
gobstopper
(@gobstopper)
Active Member

oh these are shimano brakes

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Posted : 27/08/2018 9:33 pm
Fadgadget
(@fadgadget)
Famed Member

Sounds like the pistons have popped out or have came out too far.  Pushing back the pistons on Shimano brakes require you to use a plastic tyre lever or something similar as the pistons have ceramic tops which can crack easily if forced back by a screwdriver.

Take the pads off and gently push back both pistons until they are fully home, fit spacer and rebleed.  

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Posted : 27/08/2018 9:45 pm
gobstopper
(@gobstopper)
Active Member

I've tried pushing the pistons back in with a brake lever but they are not moving back. Should I open the bleed port on the lever and then try push them back in?

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Posted : 27/08/2018 10:06 pm
EuanS2
(@euans2)
Reputable Member

Yes, that should allow the pistons to move freely but you may well need to re bleed the system afterwards.

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Posted : 28/08/2018 12:19 am
gobstopper
(@gobstopper)
Active Member

Managed to get the pistons back in by opening the bleed port on the lever. Unfortunately after re bleeding the same problem persists. Every time I press the lever (with the bleed block still in) the fluid drips out of the left piston, I can also hear a slight grinding noise.  I'm thinking that dirt might have got in to the seal and wrecked it............ 😥 

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Posted : 28/08/2018 1:17 am
Fadgadget
(@fadgadget)
Famed Member

Looks like the seals have gone or the piston has a crack in it. No option but to buy a full calliper for it as it's a faff changing them and the seals for Shimano. I have two spare XT calipers at home that leak oil because the pistons were pushed back at an angle buggering the seals. 

Even better, buy a new brake kit. 

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Posted : 28/08/2018 1:49 pm
gobstopper
(@gobstopper)
Active Member

Confirmation of a broken piston.

Took the bleed screw out and this bit of plastic fell out. Do you think this fault will be covered under warranty? The brake is less than 2 years old.

 

1535483662-201808281731202916.jpg
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Posted : 28/08/2018 8:14 pm
Fadgadget
(@fadgadget)
Famed Member

Hi. Nope it will not be covered under warranty I'm afraid.  New Calliper time as its easier to get this than seals or pistons. 

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Posted : 28/08/2018 10:16 pm
gobstopper
(@gobstopper)
Active Member

New caliper should be with me tomorrow 👍  Thanks for your help.

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Posted : 29/08/2018 3:39 pm
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