goldfinch

I have a 2014 Mountain bike with hydraulic Shimano SLX brakes. Brakes never bled. Mushy lever on rear brake. friend suggested that I bleed the brake as pad change didn't cut it. I bought a bleed kit and watched all sorts of videos. I had a total failure. I first thought I would just use gravity to drain the fluid. Well, fluid hardly drained. So I started over and tried sending fluid from the caliper port to the little cup on the brake lever. I could not push out any fluid from the syringe.

Ideas?

This is very frustrating as of the zillions of videos I could find none dealt with problems in bleeding brakes.

cxwrench

Obviously the bleed port on the caliper has to be open and the plug has to be out of the cup. Right? Otherwise there is absolutely nothing that should stop you from pushing fluid up for the caliper through the lever. It's very simple and problems like this are exceptionally rare.

goldfinch

I know, I know. I meticulously followed instructions. Top port open, cup screwed in, plug out. Bottom port opened after attaching hose. First opened 1/8 turn, went as far as 1/2. Syringe moved nothing.

cxwrench

Open the caliper bleed screw more. I usually open them 3/4 to 1 turn. I NEVER drain the fluid out through the caliper, I ALWAYS push fluid up from there to the lever. Then I close off the caliper and 'burp' the lever by repeatedly squeezing the lever w/ the cup installed and some fluid in it so I can see the bubbles of air come out.

ETA: I know this sounds stupid but I've done it and seen others do it...make sure the cup is actually on the lever that's connected to the caliper you're putting the syringe on. I've put the syringe on the rear caliper and then put the cup on the front lever. That NEVER works

goldfinch

Open a full turn, nothing. Yeah, it is the correct lever.

goldfinch

I can't think of a thing to do here. Make sense to spend $50 for a replacement rear brake lever/cable/caliper set? Or is there something else short of that to try first? Like disconnecting cables and seeing if fluid goes through? I am not sure what I would do if it did or didn't though.

Canker

Take the bleeder out completely and blow through it, or use carb/brake cleaner or a can of compressed air or air compressor. Probably too tiny to blow through with your mouth. If nothing else swap bleeders front to back.

goldfinch

I'll try this next.

goldfinch

I cleaned the bleeder. Didn't work. I swapped bleeders with the front brake. Didn't help, still can't push syringe. I ended up with a nice explosion of mineral oil by pushing too hard. Dang it.

Badger6

Is the brake hose kinked? It can happen. If it is, replace it, then follow the process for fill/bleed.

goldfinch

I checked for line damage and kinks early on.

Badger6

👍🏻

There’s another thread (also in the mechanics sub-forum) where another person ended up having a blockage in their lever, and I think they had to have it replaced. I’ll see if I can find it when I get home and I’ll link it for you if you haven’t seen it yet.

Badger6

I found it, check it out here. But, it's for road disc...the only takeaway I get that could maybe be similar, is something inside the lever or caliper that is blocking the fluid passages. I dunno.

goldfinch

Thanks for the link. my hunch at this point is that it is something in the lever. In the interest of getting on the mountain bike before I head back north I ordered a replacement rear brake system (lever, cable and caliper) . When it gets here I am going to take apart the old one and see if I can at least figure out what happened.

Amt0571

I only had this issue with Avid Elixir 3 brakes years ago. The lever was damaged.

If fluid is not pushing through, I would disassemble the lever/caliper it and see what is blocking it.

It's messy, but being a Shimano brake, at least you're not dealing with corrosive fluids.