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When oil blew out of the bleed cup, did you see it come out of the cup? It sounds like the over pressure valve.
Just to check, are you doing the bleed as per Shimano’s instructions? It’s late and I might be mistaken but I thibk the procedure if: bleeding bottom-up until no more bubbles, remove bleed cup, seal shifter, pull brake lever all the way and hold to the bar, gently repressurise with syringe while slowly allowing brake lever to release, do not add excess pressure with the syringe it should move the lever all the way out and feel firm and that’s all, seal calliper, test.
Eseman-
Interesting. Yeah it definitely came out the cup. After that I was initially able to feed liquid from the calliper to the lever. At the start there were loads of micro bubbles, frothy almost. Then it got better.
I bled (or tried to) as per the shimano R8070 dealers manual. Fill from the bottom, gravity bleed to remove bubbles, depress lever and open/close valve on the calliper quickly. Oil in cup and pump lever, moving bike angle and tapping everything to get bubbles out.
That wasn’t doing much so I started again and no oil would pass through the system.
I have tried loads since and it looks like I can’t even gravity fill/bleed with a cup at the top. I even left it overnight with a full cup and the hose disconnected at the calliper. Nothing left the cup. But if you pull the lever, oil comes out the hose at the bottom.
cjr
Right, I'm at my wit's end. A few weeks ago, my Di2 Hydro (R8050?) brakes had really long travel, as metioned above, but it got worse. Possibly caused by two train trips when the bikes were hung up for 3hrs by the front wheel.
Rear has been a bit funny since I switched to a new bike in particular the lever not returning all the way back to the correct position after braking. To eliminate a kink in the hose, I replaced the hose, cleaned the caliper/pistons and tried to re bleed it. Oil will flow top to bottom, but I can't get it to flow from a syringe up to the shifter.
It suddenly popped and oil flew out bleed cup, then filled normally. But as I proceeded with the bleed (gravity etc) the shifter wasn't getting firm. So I tried again and I can't get anything through the system with the syringe. If I pull the lever, it pushes oil out the caliper, so it goes one way.
Is my very expensive and out of stock shifter F&*ked? Is there any way to try and flush out the lever to clear the blockage?
Added a pic, the upper silver bar that I think connects to the master cyclinder doesn't go all the way to the right. It does on the other shifter.