Ultegra shifter leaking after pushing pistons back – fixable?

I have just fitted some new pads to my Ultegra R8020 brakes. Pushing the pistons back has made fluid leak from the reservoir cap though. Pulling the lever makes more come out.

I’m out of mineral fluid at the moment anyway but if I get some in the morning is the fix as simple as removing the reservoir cover, reseting the rubber seal, bleeding it and then riding? Will I be able to go for a ride tomorrow afternoon?

They’re secondhand and apparently the seal isn’t available on its own so I can’t warranty it or buy new bits.

Maybe they were over filled to begin with and you’ve just purged the excess?

Funnily enough I had exactly the same thing happen when changing pads earlier this week. I think my system must have had too much oil in. Mine bubbled for a while when I first pulled the lever, but seems to be working fine now. I’ve ridden with it a couple of times since.

apparently the seal isn’t available on its own so I can’t warranty it or buy new bits.

A new bleed screw and o-ring is £2.99 – any bike shop can get you one. In stock with Madison.

Mine didn’t leak out of the bleed screw, it came out of the side of the lever

Yeah, it’s from the side not the bleed port. I’ve circled it in this picture.

It looks like a little port. It seems there’s a tiny bit of rubber in there and it bubbles from around that. The brake doesn’t work anymore, the lever pulls to the bar and nothing happens. Some bubbles of air come out of that port but the brake has clearly lost too much fluid.

If yours revived itself benman I’ll get some fluid and bleed it and if that doesn’t solve it I’ll get investigative if no one has any answers.

Yep, my oil came out of the exact same spot. I was hoping it was a bleed port too! I’ve had similar on SRAM brakes in the past when they were overfilled with fluid.

I had fluid leaking out of an Ultegra lever in the same place and it got swapped under warranty.

As I say, warranty isn’t an option for me so I really need to figure out how to fix it.

Look for turboferret/rich post.

He had issues with leaking ultegra levers….

Repaired it with an inner tube.

I was mainly suggesting that it’s not something that should be ignored. Mine was still working fine after an initial pull of the lever but leaving it like that wasn’t a long-term proposition.

Right then, seems it is fixable. These were R8020 shifters while turboferrets were the older R785s so his fix didn’t apply. What appears to have happened is the pressure overwhelmed the rubber diaphragm beneath the reservoir cover and unseated it. I’ve taken it apart and put it back together with a new bleed and so far I’ve ridden about 80 miles of mixed road and gravel on it and though it bubbled a bit from the same port to start with it’s now stopped – I think that was just residual fluid being forced out under pressure.

1- Peeled back the hood and there is fluid leaking out of the notch to the left of the right hand bolt.

IMG_20200702_104404 by Luke Bradley[/url], on Flickr

2 – Removed the reservoir cap (using stupidly tiny T8 torx bits)

IMG_20200702_105440 by Luke Bradley[/url], on Flickr

3 – Laid the bike on its side and had a look at everything. The cap, diaphragm and lever body were covered in brake fluid.

IMG_20200702_105716 by Luke Bradley[/url], on Flickr

IMG_20200702_105720 by Luke Bradley[/url], on Flickr

4 – I cleaned up all the fluid, carefully inspecting everything as I went for cracks in the cap or lever body and tears or deformation in the diaphragm – these were all fine.

IMG_20200702_105919 by Luke Bradley[/url], on Flickr

IMG_20200702_110148 by Luke Bradley[/url], on Flickr

IMG_20200702_110445 by Luke Bradley[/url], on Flickr

5 – I topped up the reservoir with Shimano’s own mineral fluid then replaced the cap and diaphragm. It seemed better to put the diaphragm on the cap first then install them onto the lever at the same time as the sealing around the bolt holes was pretty specific to the shape of the cap.

IMG_20200702_110252 by Luke Bradley[/url], on Flickr

IMG_20200702_110313 by Luke Bradley[/url], on Flickr

6 – Pretty terrible photo but it was hard to capture – when I pulled the lever there was still a small bubble of fluid coming out of the notch next to the right hand reservoir cap bolt. I suspect this was extra fluid that had leaked out when I put the reservoir cap back on. It’s now stopped and after a bleed the brake is firm and the bite point consistent again.

IMG_20200702_112801 by Luke Bradley[/url], on Flickr

Nicely done and great how-to for others.

I thought it needed putting together because Google doesn’t come up with much – just “I took it to the bike shop and replaced a plug” or “it’s a warranty job, send it back”. Hopefully it helps someone else out – it took me less time to fix than it did to find mineral oil in stock at one of the four bike shops nearby!

This just happened to me, in fact I made another thread about it before I saw this one: https://singletrackworld.com/forum/topic/mineral-oil-shot-out-my-road-shifter-bad-and-how-to-reduce-throw-on-105/#post-11894562

Brake worked fine after a rebleed, a bit more oil leaked out but judging from your exp I should be fine.

Mine is still going fine a year later too.

Maybe they were over filled to begin with and you’ve just purged the excess?

This.

The reservoir seal isn’t intended to resist pressure. When you squeeze the lever, a small amount of fluid is displace through the transfer port back into the reservoir before the transfer port closes. Once the transfer port closes, the master cylinder becomes pressurized, but this is isolated from the reservoir. If you overfill them, there is no space in the reservoir to take that excess fluid so it will be forced past the seals. All you need to do to fix this is to open the bleed port and squeeze the lever, then close the bleed port with the brakes applied. Or just wipe off the fluid and ignore it, it won’t cause the brakes to fail.

Just resurrecting this! I’m having exactly the same problem. What was the actual fix? Do I have to take the reservoir etc out , clean and reinstall?

The diaphram seal can be burst if there’s too much fluid in the system when the pistons are pushed back, but this has since become a serviceable part, presumably because this was happening quite frequently.

If this is your problem, you can get either a left shifter or right shifter kit to fix it.

Definitely a case of Shimano doing the right thing for once and saving people from chucking away otherwise working shifters. Nice one!

Definitely a case of Shimano doing the right thing for once and saving people from chucking away otherwise working shifters. Nice one!

Also kudos to SJS Cycles for stocking these little bits and bobs, saved me many times.

@turbo1397 – it was basically as simple as taking it apart, cleaning it, putting it back together and bleeding it. If you have a tear in the diaphragm you can now get new ones from the links in the post above.

Also kudos to SJS Cycles for stocking these little bits and bobs, saved me many times.

Genuinely, I would love to visit their shop. I have a vision of an Open All Hours Aladdin’s cave of weird and wonderful parts, served by wizened old men wearing brown shop coats and offering to wrap up your purchases for you.

I’m sure it’s nothing like that, but SJS is a wonderful resource for weird Shimano bits and bobs! Now, if only Shimano would sell the races for their pedals, rather than just axle assemblies, we’ll all be much happier…

Resurrection with a question…

I found this thread when I did exactly this a few months ago. Pushed pistons back, squirted oil out of the weep port,  instant regret. My chum did this yesterday also and spent time faffing putting it right.

I don’t understand how it happens. Assuming the brake is originally bled with new pads and a new (full thickness) disc, the system will be full of oil with the pistons partly out in their ‘ready to brake’ position.

As you wear the pads down, the pistons extend further to compensate for the thinner pads. The master cylinder diaphragm presumably gives a bit as the oil level drops as the pistons extend. There’s no more oil in the system just the amount you started with – make sense so far?

Assuming you never add extra oil,  the oil in there is the right amount for fresh pads newly bled. So when you remove knackered pads and push the pistons back to put new ones in, you’re returning the system to its original state – make sense?

So why do we suffer diaphragm blow off/oil expulsion? Does air get in there and push the diaphragm aside then letting the oil escape or something else? Witchcraft?

I’m loath to undo the bleed port every time I push pistons back in case it introduces air then needing a rebleed.

Any ideas from the clever people please?

How would opening the bleed port introduce air?

The bleed port lives on top of the STI. If you open it, air lives outside and (presumably) can get in as the master cylinder is (usually) not brimmed with oil. Make sense?

It’s not going to suck air in!!! Put the bucket in the bleed port with a dash of oil if you are that worried

OK. Back to the original question. Why does it happen at all?

Brake should be bled with the bleed block rather than pads and rotor.