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Leaking M6100 lever

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HollyBoni

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Discussion starter · #1 ·
I think my right M6100 is leaking. At first I thought it was the olive, but it seems like it's coming from the piston area, dripping down to the underside of the lever. The brakes still feel good tho, it doesn't feel like there is air in them. I wiped it off a few times but it keeps coming back. Some pics:

Image

Image


That grey stuff around the pivot point on the lever is oil. Weirdly I don't see much oil coming from the piston? What do you guys think, where is the leak coming from? Can I fix it somehow, or is it new lever time?
 
#2 · (Edited)
HollyBoni said:
I think my right M6100 is leaking. At first I thought it was the olive, but it seems like it's coming from the piston area, dripping down to the underside of the lever. The brakes still feel good tho, it doesn't feel like there is air in them. I wiped it off a few times but it keeps coming back. Some pics:

View attachment 1988319
View attachment 1988318

That grey stuff around the pivot point on the lever is oil. Weirdly I don't see much oil coming from the piston? What do you guys think, where is the leak coming from? Can I fix it somehow, or is it new lever time?
Click to expand...
Could it be it's been slightly overfilled and excess fluid is just weeping out of the diaphragm above or maybe it has a small repairable hole?

If it is the piston seals or diaphragm it could be salvaged with spares from a similar donor lever.

Alternatively there are some aftermarket pistons and/or seals on ebay, etc. I keep old stuff for spares but maybe worth a shot as a last resort?

Example:-
www.ebay.co.uk

Titanium MTB Brake Lever Piston For Shiman-o XT M8000 M7000 SLX M785Repair Part | eBay

(For: XT M8000 M7000 SLX M785. RISK XT/SLX Titanium Brake Lever Piston. Material: titanium alloy. 1) Titanium alloy material, will not rust, durable. 2) Hollowing out/new design to reduce weight. Color: Silver.
www.ebay.co.uk
 
#3 ·
Some have ruptured the diaphragm on the reservoir on these latest shimano x100 -series brakes by overfilling or pushing caliper pistons in too aggressively. If this would be the case, the leak would be from the reservoir end cap, but on the photos there is no sign of oil from there, so likely the diaphragm is intact.

Another option is that dust/dirt has seeped in to the master piston area and is now stuck in the cylinder walls, allowing the main piston seals to leak some oil out. If this continues leaking, I would first try to dismantle, clean and rebuild the lever internals. Most likely cleaning and rebuilding will be enough to stop the leaking(if it comes there in the first place) and no need to hunt for new seals or piston. If it is dust/dirt that has found its way to the main cylinder, it will also work as abrasive paste and can develop wear/scratches on the cylinder walls if not cleaned, this increases the likelihood of leaking in the future too.
 
Discussion starter · #4 ·
Yeah the reservoir end cap looks bone dry. Also, the rear brake fluid turned pretty dirty in the rear in just 7-8 months, so i'm thinking it's the seal letting crap in, and letting oil out.

I've seen those aftermarket pistons. I'll have to find someone who sells them in the EU and ships here, I don't really want to wait a month+ right now for stuff from China. I'm going to try stripping down the levers first.
So there is no Shimano rebuild kit, or anything? Luckily these are cheap levers tho.
 
#5 ·
HollyBoni said:
Yeah the reservoir end cap looks bone dry. Also, the rear brake fluid turned pretty dirty in the rear in just 7-8 months, so i'm thinking it's the seal letting crap in, and letting oil out.

I've seen those aftermarket pistons. I'll have to find someone who sells them in the EU and ships here, I don't really want to wait a month+ right now for stuff from China. I'm going to try stripping down the levers first.
So there is no Shimano rebuild kit, or anything? Luckily these are cheap levers tho.
Click to expand...
No harm in stripping it all down and having a good look. Could be an obvious problem with the piston seals on inspection.

No such thing as Shimano rebuild kits or genuine spares, only aftermarket stuff.

A lot of seals and parts are pretty much interchangeable between a lot of calipers and levers so it's occasionally worth keeping hold of old units for repairs or maybe even buying second hand 'parts only' items. 🪙🪙
 
Discussion starter · #7 ·
BurnieM said:
BL-M6100 levers are only 35 euro.
Just replace it ?
Click to expand...
Well those "just 35 eur" items are starting to add up... 🙂 Bit fed up with spending money on my bike ATM.
First I'll have to see if I can find one. Originally I bought the left and right from abroad from two different shops because no one had stock. Maybe it's different now tho.
Also wanted to see if there is a quick and easy fix.
 
#8 ·
HollyBoni said:
Well those "just 35 eur" items are starting to add up... 🙂 Bit fed up with spending money on my bike ATM.
First I'll have to see if I can find one. Originally I bought the left and right from abroad from two different shops because no one had stock. Maybe it's different now tho.
Also wanted to see if there is a quick and easy fix.
Click to expand...
Well most of work is done already. You're only another ten minutes or so away from a total individual parts strip down.

Even if it's not fixable I wouldn't be able to stop there without at least trying to find out what the problem is. 🤔
 
Discussion starter · #9 ·
Reaperactual said:
Well most of work is done already. You're only another ten minutes or so away from a total individual parts strip down.

Even if it's not fixable I wouldn't be able to stop there without at least trying to find out what the problem is. 🤔
Click to expand...
Yeah i'm gonna take it apart for sure. Just too lazy to do a full bleed right now. 😅
 
Discussion starter · #10 · (Edited)
Finally took the thing apart mainly out of curiosity.
Image


Visible wear on the piston and some wear on the outer seal. There is some scoring on the cylinder walls but not sure how smooth they are from the factory to be honest. Oil was grey.

I'm guessing some dirt or something must have gotten in there and wore things out. Or maybe I sprayed some alcohol in there accidentally when cleaning the levers and it damaged the seals.
 
#11 ·
HollyBoni said:
Finally took the thing apart mainly out of curiosity.
View attachment 1990231

Visible wear on the piston and some wear on the outer seal. There is some scoring on the cylinder walls but not sure how smooth they are from the factory to be honest. Oil was grey.

I'm guessing some dirt or something must have gotten in there and wore things out. Or maybe I sprayed some alcohol in there accidentally when cleaning the levers and it damaged the seals.
Click to expand...
A master cylinder bore would be almost like a mirror finish and smooth as silk under normal circumstances.

Difficult to say if some scoring on the cylinder itself is going to be a problem.

I suppose at least you've identified the route cause of the leak. I'd replace the whole lever after looking at the pic just in case and keep hold of that one, could come in handy one day.
 
Discussion starter · #12 · (Edited)
Reaperactual said:
A master cylinder bore would be almost like a mirror finish and smooth as silk under normal circumstances.

Difficult to say if some scoring on the cylinder itself is going to be a problem.

I suppose at least you've identified the route cause of the leak. I'd replace the whole lever after looking at the pic just in case and keep hold of that one, could come in handy one day.
Click to expand...
Yeah it's new lever time for sure. It's sweet that there was no degradation in performance tho. No spongy lever, no reduced power. I did top off the lever 2-3 times tho, but that takes like 3 minutes.
 
#13 ·
Alcohol( iso propyl) should not damage the seal, and most likely cleaning and re-greasing the seals and cylinder bore + rebuild will make it work OK again, even if there is some visible wear marks on the piston/cylinder. The wear is also likely only on the outer end of the cylinder bore, where no big pressures should appear over the outer seal. The inner seal takes most of the pressure when you press the lever, while the outer one is is trying to do its job in keeping the reservoir fluid in and air/dirt out (although it sucks on the latter one). As you mentioned too, there was no degradation of performance, just minor leak...

What I'm trying to say here, is that even if the internals looks quite bad visually, it will most likely still function OK in real life after cleaning & rebuild, so not necessarily new lever time yet...
 
Discussion starter · #14 · (Edited)
Verttii said:
Alcohol( iso propyl) should not damage the seal, and most likely cleaning and re-greasing the seals and cylinder bore + rebuild will make it work OK again, even if there is some visible wear marks on the piston/cylinder. The wear is also likely only on the outer end of the cylinder bore, where no big pressures should appear over the outer seal. The inner seal takes most of the pressure when you press the lever, while the outer one is is trying to do its job in keeping the reservoir fluid in and air/dirt out (although it sucks on the latter one). As you mentioned too, there was no degradation of performance, just minor leak...

What I'm trying to say here, is that even if the internals looks quite bad visually, it will most likely still function OK in real life after cleaning & rebuild, so not necessarily new lever time yet...
Click to expand...
Not sure what kind of alcohol I have, I get it from work, all I know that it's 96% (at least). One time I cleaned an o-ring with it and it wouldn't seal anymore after that. 😅

Ordered a new lever already, I might still assemble this one until I get the new one.
I have some trips planned abroad in the coming weeks, so I want my bike to be a 100%.
 
Discussion starter · #16 ·
vnslnc said:
Hey, guys. I have the same problem. Did you find these pistons to be sold( with its seals) seperately anywhere online? Or could we use slx/ xt ones? only those are available, as far as I searched
Click to expand...
You can get titanium pistons with seals or just seals on AliExpress/ebay, they claim it's compatible with most Shimano levers but who knows.
Did you find genuine SLX/XT seals? Could you post a link please? If they're cheap, I'd just buy them, take out the stock ones and compare them.
 
#17 ·
HollyBoni said:
You can get titanium pistons with seals or just seals on AliExpress/ebay, they claim it's compatible with most Shimano levers but who knows.
Did you find genuine SLX/XT seals? Could you post a link please? If they're cheap, I'd just buy them, take out the stock ones and compare them.
Click to expand...
No, not genuine sadly. About the same as you mentioned, but on ebay. It's just they never mention deore, only slx and xt names.
 
Discussion starter · #18 ·
vnslnc said:
No, not genuine sadly. About the same as you mentioned, but on ebay. It's just they never mention deore, only slx and xt names.
Click to expand...
Unless it's urgent (shipping will probably take a while) I'd order them and compare them to the stock ones. The ones I've seen on Ali were like €5 (just the seals) so it's not a big loss if they don't work out.
Even if they fit, they might not solve the leaking problem if the cylinders are all scored up inside.
 
#19 ·
HollyBoni said:
Unless it's urgent (shipping will probably take a while) I'd order them and compare them to the stock ones. The ones I've seen on Ali were like €5 (just the seals) so it's not a big loss if they don't work out.
Even if they fit, they might not solve the leaking problem if the cylinders are all scored up inside.
Click to expand...
Just search for "brake lever piston shimano" on ebay.co.uk / ebay.com depending on where you are and in Advanced Filters(right next to search button, if you're using desktop site)> Item Location> check "only UK" / "only US" and you'll find ones with normal shipping time.
Please share your experience with us if you'll buy any. If any trouble I could give you item links themselves.
 
#20 ·
vnslnc said:
Just search for "brake lever piston shimano" on ebay.co.uk / ebay.com depending on where you are and in Advanced Filters(right next to search button, if you're using desktop site)> Item Location> check "only UK" / "only US" and you'll find ones with normal shipping time.
Please share your experience with us if you'll buy any. If any trouble I could give you item links themselves.
Click to expand...
When I first read your comment, I thought you wanted to order one yourself. Now I see it is a suggestion. Did you solve this problem of ours anyway? If yes, how?
 
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