Helping out my father-in-law by bleeding the hydraulic brakes on his old MTB. The brakes are Hayes and take DOT4 fluid.
Back brakes were easily done (fluid was filthy), but the front brakes did not want to bleed. Tried flushing from caliper to bleed valve – no joy. Tried flushing from bleed valve down to caliper – again, not joy. Took the cover off the reservoir to find it full of a jelly-like substance under the rubber seal, which I assume is old DOT4 that has absorbed a lot of water over the years.
Can anyone confirm whether removing the brake leaver from the hydraulic line and then cleaning out thoroughly with automotive brake cleaner is the best solution here, before reassembly and flushing with clean DOT4?
by prnpenguin
2 Comments
I would either wait for answer from somebody knows for sure or go to a bicycle shop and ask them I have never had a bike with hydraulic brakes if I did the first thing I do when I got it is I take it and take it apart and see about changing the fluid cuz most people don’t even think about changing the hydraulic fluid
You are looking at a complete clean and rebuild here. Get the rebuild kit and a guide if you feel brave enough or bring it into a shop to get it cleaned and rebuilt. You will have to replace the hoses as well.
This is why mineral oil brake systems are vastly superior, the fluod is hydrophobic instead of hygroscopic. I’d replace to the basic Shimano hydro brakes to counter any future problems.