Brake bleeding issue

[abaton6]

I'm working on my "new" 81 GS 650. She has been sitting for God knows how long. The rear brake fluid looked black, so I thought I'd flush it out. I hooked up my Mighty vac tool, and I cannot get any fluid to come out. I have bled a lot of brakes, but never ran into this issue before. As I'm writing this, I'm wondering if the rubber brake line is so old, it has swollen shut. Thoughts?

[GregT]

It's a possibility - but more likely is that the mastercylinder is full of crud and the vacuum is drawing it into the cylinder replenish holes.
I'd do a careful strip and clean of the whole system.

[tom203]

It's a possibility - but more likely is that the mastercylinder is full of crud and the vacuum is drawing it into the cylinder replenish holes.
I'd do a careful strip and clean of the whole system.

Oh yeah.. I picked up two spare rear master cylinder to this model and both are seriously corroded . Fortunately , I've haven't needed to attack them yet.

[abaton6]

I'll check that out tomorrow. I can check out the brake line at the same time. Thanks.

[Nessism]

You need to do a full system teardown. You can't bleed through chunks. If you need new seals the OEM parts are much better than aftermarket like K&L.

And replacing the brake lines should be considered mandatory. They are currently full of scale on the inside and UV deteriorated on the outside.

[hannibal]

The factory manual calls for replacing the lines every 2 years. You're probably a little over due.

[Redman]

Have you tried pumping out the sludge with the master cyclinder? Pressure on the lever then crack open the bleeder valve.
That might clear it out enough for then using the vac pump might work.

.

[Nessism]

Have you tried pumping out the sludge with the master cyclinder? Pressure on the lever then crack open the bleeder valve.
That might clear it out enough for then using the vac pump might work.

.

Don't encourage him Dave. Brakes must be taken seriously.

[LAB3]

When I got my bike after it had sat for 23 years the front brake lever wouldn't move at all. Thinking the master cylinder was siezed up I ordered a cheapo replacement, a new line and caliper rebuild kit knowing it was best to go through the whole thing. When I went to take off the master cylinder and broke the line free, the lever moved just fine leading me to believe that the line was indeed what was plugged. Brake lines are very affordable and with them being a regular maintenance item, they're best replaced.

[fastbysuzuki]

As said in other posts you need to do a complete overhaul of the braking system including new master cylinder and caliper seals along with new brake lines. Trying to do cheap on brakes will lead to disaster, yours and likely some innocent person/persons.

[abaton6]

Update on the brake bleeding problem. First, thank you all for helping out a brother. OK, I removed the M/C and discovered it was full of rust and the piston is frozen. Just for fun, I forced air through the line, and it is open. So, it looks like l need a new M/C, brake line, and probably a new caliper,(or a rebuild kit). Curiously, the front brake works fine, but I did flush out the fluid, which did not look bad. Any suggestions for the best [place to get these parts would be appreciated.

[abaton6]

The factory manual calls for replacing the lines every 2 years. You're probably a little over due.

Just a bit,..lol

[LAB3]

Update on the brake bleeding problem. First, thank you all for helping out a brother. OK, I removed the M/C and discovered it was full of rust and the piston is frozen. Just for fun, I forced air through the line, and it is open. So, it looks like l need a new M/C, brake line, and probably a new caliper,(or a rebuild kit). Curiously, the front brake works fine, but I did flush out the fluid, which did not look bad. Any suggestions for the best [place to get these parts would be appreciated.

eBay is your friend! Generally you can get a little better price when you take shipping into consideration for OEM parts and anything from dirt cheap to way overpriced for aftermarket.