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Discussion Starter · #1 ·
Hi,

I need help with my Deore XT M8000 Brake Lever. I added mineral oil on it using a syringe , i think i i accidentally put a small hole on my brakes. Now it is leaking.


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I checked the manuals on the shimano website and i can't seem to find any information how to fix my problem. I kindly ask for help to give me advice on how to fix the issue.


Thank you.
 

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If the fluid is leaking from that part of the lever, you've got a seal leak most likely. Probably a warranty issue. That repair is generally not user serviceable. I'd call Shimano and discuss it with them or go back to where you bought them and perhaps they can handle the warranty claim.
 

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Discussion Starter · #3 ·
i dont have warranty on my xt. im planning on fixing it myself. i already emailed shimano, and still waiting for reply.

i was hoping that someone in this forum may have dismantled or fixed something on their m8000 brakes. i need to know what is inside for me to fix & to find a way to seal the leak.

thanks for the advice
 

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that is the "blow off" valve for when there is too much fluid in the system or the fluid gets hot and expands.

a relief valve.

there is nothing wrong if it passed some fluid, especially after you just added some.

notice how it's located at the highest point in the system?
 
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that is the "blow off" valve for when there is too much fluid in the system or the fluid gets hot and expands.

a relief valve.

there is nothing wrong if it passed some fluid, especially after you just added some.
I've not read or seen this on any shimano advertisement so if you have any sort of link to show/state this that would be great.
 

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Discussion Starter · #7 ·
that is the "blow off" valve for when there is too much fluid in the system or the fluid gets hot and expands.

a relief valve.

there is nothing wrong if it passed some fluid, especially after you just added some.

notice how it's located at the highest point in the system?
i am really not sure how it works. yeah, i was dumb using syringe to add fluid. and somehow i accidentally punched a hole through the "relief valve". if it was suppose to work like what you said, there must be something inside that is really soft and design to expand.

i was able to turn in about 90 degrees and now the leak is barely noticeable but a still leaking. still thinking of a way to completely seal the leak. thank you for the info, helped me a lot.

Not sure why you would add mineral oil with a syringe directly into the lever. If you have fluid level issues, I recommend you follow the proper bleed instructions in the manual you found on the website.
yeah, my bad. and im sorry for it. unfortunately i dont have the proper equipment, that's why i improvised.
 

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i am really not sure how it works. yeah, i was dumb using syringe to add fluid. and somehow i accidentally punched a hole through the "relief valve". if it was suppose to work like what you said, there must be something inside that is really soft and design to expand.

i was able to turn in about 90 degrees and now the leak is barely noticeable but a still leaking. still thinking of a way to completely seal the leak. thank you for the info, helped me a lot.
don't turn anything in 90 degrees .

it is a relief valve to release excess fluid.

it is not to be tightened.

it will stop leaking on it's own.

if your system didn't have a relief the brakes would lock up when overfilled.
 

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ok. thank you. ill wait & see.
i have a similar problem when i bled the system. it squirts oil out of it when i press the lever. initially the bite was immediate but now its in the middle. not leaking anymore but i'm not confident with any brakes when oil is leaking from the lever (same issue as the picture above).

Any update on yours? did you add more oil after or everything went well?
 

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Discussion Starter · #12 ·
i have a similar problem when i bled the system. it squirts oil out of it when i press the lever. initially the bite was immediate but now its in the middle. not leaking anymore but i'm not confident with any brakes when oil is leaking from the lever (same issue as the picture above).

Any update on yours? did you add more oil after or everything went well?
Its good now. It sealed it self. However it took abt 3months. I just had to fill it again with brk fluid
 

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shimano has specific bleed and fill procedures

using a little fluid tank/container you screw
onto the lever top hole, and bleed syringe and tube filled with oil down at the caliper

and you pump/drain fluid till no bubbles come out

then rotate lever 45 deg up and down and squeeze using a brake block
to get the last bubbles out
 

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I just slapped on some m8000 on that was given to me by a friend. Put in new brake pads but had to push the pistons way back and even then the pistons wouldnt go all the way in. Managed to put the caliper on the rotor and i unscrewed the free stroke adjustment out. Squeeze the lever a few times and yup fluid shot out of that hole... So just to confirm, that's part of the design? It's still pretty tight in there... Should I take open the bleed port and push the pistons back in and call it a day? Is there a seal or something that I need to replace? Thanks
 

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I just slapped on some m8000 on that was given to me by a friend. Put in new brake pads but had to push the pistons way back and even then the pistons wouldnt go all the way in. Managed to put the caliper on the rotor and i unscrewed the free stroke adjustment out. Squeeze the lever a few times and yup fluid shot out of that hole... So just to confirm, that's part of the design? It's still pretty tight in there... Should I take open the bleed port and push the pistons back in and call it a day? Is there a seal or something that I need to replace? Thanks
Hey Mr percussive,

I have the same problem with my M7100... However if I press the lever it looks like it has pressure and braking well.
Have you had to replace the lever or is it really a pressure valve that let the fluid come out if the internal pressure increases? Were your brakes working well after that?
I'm worried if I'll have problems with my brakes when I go out for a ride...

Thank you in advance!
 

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There IS NO pressure valve in there. It's a rubber diaphragm not unlike a condom. Those who say there is hasn't taken it apart to see what's actually inside.
I had added too much fluid in my XT 8120 and it popped the bladder. Luckily it was a small rip that I just used super glue to glue the hole closed. You'll have to take it apart to fix it
 
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