Shimano Brake Fittings Leaking

AaronM

Likes Dirt
Backstory:
Brand new Merida Crossway with basic Shimano hydraulic calipers. Leaking oil from the hose fitting at the threads.

To my thinking this indicates the olive or insert (been reading si.shimano tech docs) isn’t seated well. The nut is tight but that means nothing if cross threaded or other issues with fitment.

I’ve ordered a bleed kit and a new nut/olive/insert set so my current plan is:
  1. Undo and inspect old nut/olive/insert
  2. Clean up and check thread on caliper body.
  3. If there’s any shenanigans with the hose end fittings and nut cut off and redo with new bits.
  4. Reassemble
  5. Bleed
If that doesn’t solve it spend $50 odd on a new exact same caliper/hose/lever set and move on with life.

Every search I’ve done is always pointing the finger at the piston seals, which it definitely isn’t, so actual shared experience with hose fitting issues doesn’t come up often. Anyone here had a similar issue?
 

creaky

XMAS Plumper
Sounds like you are on the right track.

If it’s brand new, shouldn’t it be a warranty issue though? At least inform the retailer what it is doing and what you are doing so that if a new brake is ultimately required, that could be through warranty.
 

AaronM

Likes Dirt
You’re right, it would be warranty if I had any confidence that the shop would do anything beyond add some thread lock and oil :)

Seriously though, if they can give a timeframe that works then I’ll bump it over but the last call I made to them was “not until January”. I get that they’re busy but considering the last warranty thing they did for my bike held up for less than 10km and my fix has been good for 300km now I not filled with confidence even if the do see it.
 

Flow-Rider

Wheel size expert
Every search I’ve done is always pointing the finger at the piston seals, which it definitely isn’t, so actual shared experience with hose fitting issues doesn’t come up often. Anyone here had a similar issue?
Never had issues myself but try and back the compression nut off a quarter of a turn a few times and re-tighten it, sometimes it helps to get the olive compressed a little more.
 

bear the bear

Is a real bear
Backstory:
Brand new Merida Crossway with basic Shimano hydraulic calipers. Leaking oil from the hose fitting at the threads.

To my thinking this indicates the olive or insert (been reading si.shimano tech docs) isn’t seated well. The nut is tight but that means nothing if cross threaded or other issues with fitment.

I’ve ordered a bleed kit and a new nut/olive/insert set so my current plan is:
  1. Undo and inspect old nut/olive/insert
  2. Clean up and check thread on caliper body.
  3. If there’s any shenanigans with the hose end fittings and nut cut off and redo with new bits.
  4. Reassemble
  5. Bleed
If that doesn’t solve it spend $50 odd on a new exact same caliper/hose/lever set and move on with life.

Every search I’ve done is always pointing the finger at the piston seals, which it definitely isn’t, so actual shared experience with hose fitting issues doesn’t come up often. Anyone here had a similar issue?
Where is it leaking, at the lever or at the caliper?
If it's the lever then it could be a barb/ olive issue or the nut is threaded incorrectly. You can undo the nut without requiring a re-bleed.
If at the caliper, then it could be faulty/ pinched o-rings. To inspect, this will require a re-bleed
 

born-again-biker

Is looking for a 16" bar
I had an SLX lever that weeped a tiny bit of oil on previous bike - never got around to fixing it before I retired the lever for a good price on XT.
But.... it's easy to undo the hose at the lever, schnipp off the hose just behind the olive, slide new olive on, push new insert into hose end and reconnect with nice new squishy feeling. You really don't need to tighten this stuff much when it's new - going too tight will just half-fuck it.

If it's leaking at the caliper I'll bet a case of beer it's one or both of the banjo o-rings. They're really easy to drop/lose or crush. Check them before you cut the old banjo orff.

EDIT - Using spanners that don't quite fit the compression nuts will fuck them.
Over-tightening banjo bolts will snap them - they're hollow and narrow.
 

born-again-biker

Is looking for a 16" bar
I had an SLX lever that weeped a tiny bit of oil on previous bike - never got around to fixing it before I retired the lever for a good price on XT.
But.... it's easy to undo the hose at the lever, schnipp off the hose just behind the olive, slide new olive on, push new insert into hose end and reconnect with nice new squishy feeling. You really don't need to tighten this stuff much when it's new - going too tight will just half-fuck it.

If it's leaking at the caliper I'll bet a case of beer it's one or both of the banjo o-rings. They're really easy to drop/lose or crush. Check them before you cut the old banjo orff.

EDIT - Using spanners that don't quite fit the compression nuts will fuck them.
Over-tightening banjo bolts will snap them - they're hollow and narrow.
EDIT #2 - Just accept at the start that you will be re-bleeding.
 

AaronM

Likes Dirt
Leaking at the caliper. It’s the low-end Shimano caliper without banjo fittings, but the nut and olive with barbed insert. Will try a back-off re-tighten cycle or two.

Have ordered the bleeding kit :) pretty sure 90% of the fluid is already gone anyway so was always going to have to bleed.

I have proper (automotive) spanners for working with these fittings. The theory as I was told is the nuts are supposed to be softer than the caliper material (at least on cars) so that there’s less likelihood of stripping the caliper. Plus a slightly softer nut will conform to the threads at a micro level etc. I suppose Shimano work to the same principle.

As an aside, the brake pipe spanners are the ones worth spending real money on, good ones don’t deform, last a lifetime and don’t cause more trouble than they fix.
 

T-Rex

Template denier
To redo the fitting you want to cut the hose cleanly behind the existing barb and reassemble. If you don’t have a set of Park or similar cable cutters with the V shaped jaws, you can cut the hose pretty cleanly with a very sharp woodworking chisel and a hammer on a block of wood.
 

T-Rex

Template denier
Oh and if you are going to hose the oil off the calipers with brake cleaner take the pads out first. The brake cleaner can carry the oil onto the pads and it only takes a little bit to contaminate them.
 

AaronM

Likes Dirt
I’ve been pretty diligent with wiping up the calipers and the layout helps it not get on the pads (small mercies).



It just wicks along the hose and drips under the crankset(lowest point). Will spend some time with BrakeKleen finding cuts in my hands before I do a thing rash like say “it’s all sorted”.

Did the loosen off and tighten firmly (but not fully) then repeat trick a few times. Then pulled up some slack in the hose and tightened it up ‘hard’. With some of the Aeromotive style fittings we’ve used to convert between fuel hardline and flex-lines on car builds the olives benefit from this as well and they “wear in” to a seal.

It seeped a bit until I hit ‘need to pull the special face while hoping I don’t pull the thread out of the caliper’ torque.

Appears to be no more seepage, the pads jiggle with lever application and the brakes honk like a mentally challenged goose, but no more seepage evident so I’ll say a win for now.

Now for the bleed kit to arrive (or I suck up LBS prices just so I can say it’s sorted).

Undoubtedly I’ll be posting in the Fuckwit thread in 30 minutes when it’s weeping again.
 

T-Rex

Template denier
I’ve been pretty diligent with wiping up the calipers and the layout helps it not get on the pads (small mercies).

Appears to be no more seepage, the pads jiggle with lever application and the brakes honk like a mentally challenged goose, but no more seepage evident so I’ll say a win for now.
Honking like a goose = contaminated pads. Assuming it’s pulling up ok and you can stand the noise it should be ok to take for a ride provided it doesn’t start leaking again and you run out of fluid.
 

Litenbror

Likes Bikes and Dirt
I’ve been pretty diligent with wiping up the calipers and the layout helps it not get on the pads (small mercies).



It just wicks along the hose and drips under the crankset(lowest point). Will spend some time with BrakeKleen finding cuts in my hands before I do a thing rash like say “it’s all sorted”.

Did the loosen off and tighten firmly (but not fully) then repeat trick a few times. Then pulled up some slack in the hose and tightened it up ‘hard’. With some of the Aeromotive style fittings we’ve used to convert between fuel hardline and flex-lines on car builds the olives benefit from this as well and they “wear in” to a seal.

It seeped a bit until I hit ‘need to pull the special face while hoping I don’t pull the thread out of the caliper’ torque.

Appears to be no more seepage, the pads jiggle with lever application and the brakes honk like a mentally challenged goose, but no more seepage evident so I’ll say a win for now.

Now for the bleed kit to arrive (or I suck up LBS prices just so I can say it’s sorted).

Undoubtedly I’ll be posting in the Fuckwit thread in 30 minutes when it’s weeping again.
If you can make it to the inner North one night this week your welcome to my bleed kit and I have olives and barbs. I'm with @Dales Cannon bet there is no barb in the line. PM me I'm home after 5 most nights or tomorrow afternoon if you want to sort it out.
 

teK--

Eats Squid
sometimes the hose wasn't pushed all the way into the lever as the bolt was tightened.

It is best to use a crows foot and torque wrench to snug it up. You would be surprised how tight it needs to be at the correct torque.
 

T-Rex

Template denier
If you can make it to the inner North one night this week your welcome to my bleed kit and I have olives and barbs. I'm with @Dales Cannon bet there is no barb in the line. PM me I'm home after 5 most nights or tomorrow afternoon if you want to sort it out.
This missing barb theory - sounds like you have seen it before @Litenbror . Is this an assembly error in the factory? I can’t see how it would have any hope of sealing without the olive having something hard to squeeze the hose against
 

Litenbror

Likes Bikes and Dirt
This missing barb theory - sounds like you have seen it before @Litenbror . Is this an assembly error in the factory? I can’t see how it would have any hope of sealing without the olive having something hard to squeeze the hose against
Haven't seen it but read about it. Apparently it happens when the bike is being assembled at the LBS by highly trained technicians. What I've read is at the lever but it's also possible at the caliper I'm assuming.

Thinking about it it was usually pretty catastrophic at the lever just squeeze and nothing happened where this seems to be a slower problem.

Either way, pull them off, get them apart then re-assemble properly and bleed. That should either sort it out or identify the problem further.
 

fatboyonabike

Wheel size expert
the olive will distort the end of the hose enough to give a nice firm feeling that the hose is snug in its home, but without the barbed insert it is unlikely to seal up correctly for any length of time..
for the sake of the exercise, just whip it out of both the caliper and lever and redo it, that way you can be sure it has been done correctly
90% of LBS mechanics are either muppets or teenagers or both
 
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