Had the worst week ever after a new hydraulic brake bleed went wrong

So last Thursday I did a brake bleed on a customer's Shimano XT setup, same as I've done a hundred times. Used my usual kit, followed the steps, everything seemed fine. Then Friday morning the guy comes back saying the lever goes all the way to the bar. I check it and somehow I got air in the line, but worse than that, I think I contaminated the pads with mineral oil. I spent all Saturday stripping it down, cleaning everything, and rebleeding it three times before I got it right. Lost money on the job and felt like an idiot. Has anyone else had a bleed go bad like this out of nowhere?

2 comments

2 Comments

wren65210d ago

Yeah I actually just read something about this the other day... apparently the newer Shimano bleed ports have a different thread pitch than older ones, so if you're using a generic bleed kit the fitting might not seal completely. Could be you were introducing air through the bleeder without realizing it. Also there's a trick with the XT where you have to rotate the lever while bleeding to get all the air out of the master cylinder... I've seen people miss that step and end up with a spongy lever even after a proper bleed. The pad contamination thing is rough though, once that mineral oil gets in there it's basically toast.

terryr4610d ago

Damn @wren652 you just explained my whole weekend to me. I fought with a set of XT brakes for like 4 hours and could not get the lever to stop being spongy. I was using a generic bleed kit from Amazon and I bet that was the problem with the thread pitch. I never even thought to check that. And that rotating the lever trick? Wish I knew that before I bled them three times and still had that mushy feel. Ended up replacing the pads too because I must have gotten oil on them during the process. They stop fine now but that initial bite is gone, just not the same as fresh pads. Totally learned my lesson about cheap bleed kits.