Tandem Tom

Working on a Shimano ST-R8070 brake lever. I cannot get fluid to pass through to the bleed cup. It is as if there is a blockage in the lever. I have disconnected the line at the lever and I can get fluid to that point. But it is as if I am pushing against a wall.
Did a search but no answers.
Thoughts?
Thanks!

Iride01 

I haven't had to do anything to my BR-8070's yet. But I probably ought to put fresh fluid in it since it's almost 4 yo.

So since no one else has answered that really knows, I'll add my 2¢.

Will it go the other way? fill the funnel, remove the syringe from the tube that's between it and the port on the brake caliper and have a container for the fluid to go in. When you actuate the lever, does it pump fluid from the funnel? If not, then your issue is probably right there at the funnel. You didn't leave the plug in the funnel did you?

Tandem Tom

After a conversation with Shimano tech service it was decided that the master cylinder is the problem. It is stuck possibly because of debris from a previous flushing. The lever is to be replaced as that is the only solution.

choddo

Oof. Pricey problem.

biker128pedal

My take is for new set up one should follow the directions and push up from the bottom with the syringe. Or if there is air in the system. But for a bleed fill the cup and pump with the lever while opening and closing the calliper bleed screw. Like with a car or motorcycle. Less chance to push air in. Also won’t push dirty fluid up to the lever.

50PlusCycling

I tend to go opposite what is recommended by Shimano, and bleed from the top down, rather than from the bottom up. I use the syringe at the caliper, and draw the plunger out while giving regular squeezes to the brake lever. In my experience this method gives me a firmer lever feel. This is the way it is done with cars and motorcycles.

choddo

That’s interesting but if there’s already air in there, that is less likely to get it out isn’t it?

50PlusCycling

No, it comes out. For the last century it has been standard practice an all vehicles to bleed from the top down. When I was an apprentice car mechanic, the first thing I was taught was how to do brakes. How to replace brake shoes and pads, calipers, wheel cylinders, master cylinders, and of course how to bleed brake systems. And, as I said, I get better results on bicycle brakes following the same process. My bike has the latest BR-RX820 brakes, and while I tried Shimano’s method for bleeding, I couldn’t get the lever feel that I liked.

choddo

I have the same brakes. I might give that a go next time. Mine feel fine but it'll be interesting to see if the process goes better that way round.

Troul 

i'd back feed the lever with shop compressor air & whatever residual fluid it can be pushed with. Keep the bleeder/fill port freely open.