jrw921

I watched all the videos and had the process down. So I thought. It is supossed to be a closed system, so you open the bleed port on the rear caliper first leaving the lever port closed to stop oil from flowing out of the caliper, right? Well, it didnt work because I had oil everywhere as I hurriedly tried to screw in the syringe to stop the oil flow. Then I open the top (lever end) and attached the filler cup.
Question: Why did the oil flow freely out of the caliper when the upper port was still sealed?

cyccommute 

The videos I’ve seen all mention putting a hose attached to a syringe on the bleed port before opening the bleed port. You don’t just open the bleed port. After you have displaced the old fluid with the syringe, you close the bleed port, remove the funnel (assuming mineral oil brakes), empty it, and refill it. The system stays closed at the bottom most of the time or has something attached to it that closes it off.

As for oil flowing out when your bleed port is open and the top capped, I’m not sure how that could have happened. Are you sure the system was closed at the top? Do you have a seal problem?

jrw921

It was closed at the top. I am sure. The calipers are Zoom, just a filler screw that is removed and syringe screwed into same hole. The very same setup and the lever end. There isn't a seperate bleed valve.

Iride01 

Did you remove the wheel and put something between the pucks to keep them from popping out? Perhaps whatever you used was putting pressure on the pistons and it got relieved when you opened it up.

jrw921

I removed the caliper, removed the brake pads and installed a bleed block before opening the bleed screw. Followed all the instructions in detail. I just didn't expect to be fighting a flow of mineral out out of the caliper when every video I have watched didnt encounter that problem.

Kontact 

You screw or push on the hose, then open the bleed port. On some the hose end opens the port, on others the port opens with a screw near the hose end.

jrw921

that’s my point. The bleed port and the hose connect point are the same. You cant attach a house until the screw is removed. All the how to videos show this step with no problem because the system is still sealed at the top. Mine just flowed out everywhere before I could get the hose/syringe attached. Wondering why. Trust me, if I had separate bleed nipple and port screw, I’m not stupid enough to f that up.

Kontact 

Well, no. On Shimano, Sram and Campy any bleed port opening, even at the hose attachment, is done after the hose is in place.

What brand and model brake do you have?

jimc101

The bleed screw was open and gravity?

When you say closed system, for bikes this is pretty much limited to Magura HS series rim type brakes and these have an adjustment screw/dial; all (hydraulic) disc brakes are open systems where they have a diaphragm/reservoir for self adjustment, you mention Zoom, on the basis of these, guessing you have a set of disc brakes, for questions like this, identifying the brand and the specific model of what you are working with is very important/essential

Kontact 

I had missed that the brake brand was Zoom. They do not appear to have a separate bleed port valve.

I imagine that trapped and compressed air acted like a spring, driving fluid out. One thing you could try is doing a top bleed first to relieve that pressure, then put the reservoir plug in and open the caliper.