Leaking XT brake lever

hellmansam

hellmansam

Likes Bikes and Dirt
I suspect this has happened to my HT's Leaky lever
It used to hang in the roof of the shed and my meticulously cleaned and bled brake would start squealing like a bastard for no apparent reason when ever I dusted it off for a ride, did notice one time some spots of oil on the fork leg and thought oh I must have dripped a bit from putting the cap back in the lever . Haven't ridden it much but recently put some magura calipers on it, bled nicely and bedded in well. Sweet AF I thought, then yesty I topped up the air in the tyres and gave it a quick spin around the block only to find the front brake had gone spongy :mad: A bit of swearing, off to do google search and turned up this video, looks a bit terminal if grit gets in past the first seal and then rubs back and forth with use of the brake.
 
Labcanary

Labcanary

One potato, two potato, click
What era levers are they @hellmansam?
If they are older m785's then it possibly is the piston seal issue you linked to above. It could be worth pulling them apart to see how bad the wear is.
I had a m9000 lever that had noticeable wear to the piston bore and replacing the piston seal didn't help. The matching one didn't have visible wear and worked fine after replacing the seal.
Recently I had another m9000 lever fail due to damage to the diaphragm. It started out as a small leak then one day it just oozed mineral oil.
IMG_20230806_002236~2.jpg

si.shimano.com

si.shimano.com si.shimano.com
 
hellmansam

hellmansam

Likes Bikes and Dirt
They are M7000, about 5 years old. Came across a site with replacement diaphragms a minute ago, hopefully it’s just that.
 
Labcanary

Labcanary

One potato, two potato, click
hellmansam said:
They are M7000, about 5 years old. Came across a site with replacement diaphragms a minute ago, hopefully it’s just that.
Click to expand...
Indeed. The diaphragm is easier to access than the piston.
It's a good reminder to keep our brake levers clean though! It really is surprising how much grit accumulates behind the lever blade.
Edit: and utterly shit how Shimano doesn't condone selling small parts to make repairs easier. Oh no, they want us to buy a whole new lever instead.
 
ashes_mtb

ashes_mtb

Has preferences
Labcanary said:
What era levers are they @hellmansam?
If they are older m785's then it possibly is the piston seal issue you linked to above. It could be worth pulling them apart to see how bad the wear is.
I had a m9000 lever that had noticeable wear to the piston bore and replacing the piston seal didn't help. The matching one didn't have visible wear and worked fine after replacing the seal.
Recently I had another m9000 lever fail due to damage to the diaphragm. It started out as a small leak then one day it just oozed mineral oil.
View attachment 401620

si.shimano.com

si.shimano.com si.shimano.com
Click to expand...
I’ve got a leaky lever piston now (m8000). Did you replace the whole piston or just the seal? Where did you get them from?
 
Labcanary

Labcanary

One potato, two potato, click
ashes_mtb said:
I’ve got a leaky lever piston now (m8000). Did you replace the whole piston or just the seal? Where did you get them from?
Click to expand...
You can try replacing just the seals. I've bought them from AliExpress in the past. They are a real fiddle to do.

I replaced some pistons for a friend recently and the metal replacements gave the lever actuation a fairly clunky feel in the initial phase. I'm not sure if it's because the pistons were out of tolerance, or because the bore was pretty worn from dirt ingress.

If you want to try replacing just the seals on the piston, I could send you a couple to try?
You could also try tearing the lever down completely and giving it a good clean before replacing things. In hindsight I should have maybe tried that for my friend's levers.
 
hellmansam

hellmansam

Likes Bikes and Dirt
I found the seal thingys on Amazon, they come in packs of 10, and I’ve got two of them on the way. Got my son to order them as I don’t have an Amazon account. Neither of us noticed they are a pack of 10. So I’ll have a few spares to offload when they turn up:rolleyes:
Cost was $89 all up for 20 so they are fairly cheap compared to a new lever, despite high shipping cost.
 
hellmansam

hellmansam

Likes Bikes and Dirt
Soooo got the old ‘attempted delivery’ card and had to wait until today to collect from the Starfark depot in town. There was quite a bit of stuffing around to begin with, a half duplicate order somehow got created, took a few days to sort that out and then to rub salt into the wound this is what they sent - two big envelopes with a single rubber seal thingy in each one ! I’ll add the link to this post later if they don’t take it down. TYB lodged a dispute and just messaged me that he got a full refund.
IMG_5901.jpeg
 
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