Cloudy mineral oil
 

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Cloudy mineral oil

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 PJay
Posts: 4818
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I replaced my brake pads today, and did a quick, funnel only bleed in case any air had made it in.

When I pumped the lever I could see an exchange of mineral oil and the oil coming out of the levers (both the same) was a cloudy black which I've never had before.

Is this a sign of imminent failure? The brakes have been working fine and still seem to be. Is it safe to ride until I can do a full bleed or has something started to break down?

I've got ancient SLX levers paired with newer SLX callipers. Hoping that I don't need new brakes!


 
Posted : 15/06/2022 11:43 am
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I thought all break fluid was black? It certainly is by the time I'm done with it.


 
Posted : 15/06/2022 11:45 am
 PJay
Posts: 4818
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Shimano mineral oil is pink.


 
Posted : 15/06/2022 11:45 am
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He's trying to be funny.

It's normal for your existing oil to come out murky grey, will be quite safe to ride until you can do a proper bottom-up bleed.


 
Posted : 15/06/2022 12:02 pm
 PJay
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Cheers! I'm clearly a bit slow today.


 
Posted : 15/06/2022 12:37 pm
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Mine is always a bit black, looks like a suspension of particulate.

I've always assumed it's crud that's been cleaned off the pistons/got passed the seals during operation.

I tend to keep pumping new fluid through the brake until it's clean-ish coming into the cup.


 
Posted : 15/06/2022 3:46 pm
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I've seen a hypothesis that it's some sort of dye/colouring from the seals. It doesn't appear to affect operation.


 
Posted : 15/06/2022 4:30 pm

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