Squishy wet bubbly sound from master cylinder

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Shorts · #1 Unread post by **Shorts** » Mon Jul 31, 2006 12:37 am

I just installed new stainless steel line on the front brake. Though bleeding, I cannot get a firm lever.

Unfortunately, there is some moisture sepage at the master cylinder there where the brake lever presses. I can also hear a squishy sound at full compression of the lever. I can also watch the fluid at the bleed screw tube, it pumps out with a lever pull, but when I hold the lever down, the fluid looses pressure and begins to suck back in the caliper bleed screw.

Am I looking at rebuilding the master cylinder? Or a bad bleed job?? I'm thinking bad MC, just need a 2nd opinion (my first time on motorcycle brakes).

Mintbread · Mon Jul 31, 2006 12:54 am

Did you replace the copper washers when you changed the lines?

Shorts · #3 Unread post by **Shorts** » Mon Jul 31, 2006 1:25 am

Yeah, 2 new copper washers at the top banjo and 2 new washers at the caliper.

sharpmagna · Mon Jul 31, 2006 2:25 am

I'm thinking bad bleed job, no offense on your mechanical skills. Until the lever has a firm feel to it, then it hasn't been bled of all air. Are you using a mityvac or just the old manual method? I personally don't trust the mityvac, but I'm old skewl...

Is that a new MC too? I don't remember if you got another one or you're using the stock one.

Shorts · #5 Unread post by **Shorts** » Mon Jul 31, 2006 2:43 am

I'm using the old school method. I did that on the trucks and after 2 rounds it usually firmed up nicely.

The squishy sound is coming from the lever end of MC as opposed to the banjo end. It is at the last squeeze of compression. The MC was fine before I drained it to swap hoses. Maybe cleaning it out and getting the junk off made it act up

I'm hoping it is a bad bleed job as well. I'm letting it sit overnight and will try again tomorrow.

I did not get a new MC. I got the stock one to sit right. It helped going to a banjo bolt brake light switch and using a longer brake hose (repositioning the banjo at the opposite angle).

I'll see how it goes tomorrow.

thespirit · #6 Unread post by **thespirit** » Mon Jul 31, 2006 3:52 am

Not that I have ever done this, but did you tighten the banjo bolts down good enough?

Shorts · #7 Unread post by **Shorts** » Mon Jul 31, 2006 11:44 am

Shorts · #8 Unread post by **Shorts** » Mon Jul 31, 2006 4:50 pm

Dang. It. All.

I cannot get ANY feel whatsoever back into the lever. Everything is tight. The lines have been tapped and tapped and freakin tapped. I've ran every puddle of old fluid out, heck I can see new fluid. Refilled the reservoir way to many times. What in the world am I missing!?!?!

Geez louise. I hate this bike and I haven't even ridden it yet

Ps, the squishy sound, I ran the reservoir empty...IDIOT! So I started over....now I'm still here. Stupid brakes.

#9 Unread post by **9000white** » Tue Aug 01, 2006 6:49 am

get a clean oil squirt can fill with brake fluid take a piece of hose that will fit over the bleeder screw and pump until master cyl is full then finish bleeding in the usual manner.

thespirit · Tue Aug 01, 2006 9:15 am

When I replaced some lines on my POS, I used a hose that ran to another bottle of fluid. I just started pumping away while refilling the MC as needed. Once fluid started to come out, I filled the hose to the bleed screw with more brake fluid to keep air from being sucked back into the bleed screw. I then pumped some more until I couldn't see any more air bubbles coming out. There are also better bleed screws you can get that have check valves in them. It's a little spring with a ball bearing that will allow fluid and air to come out, but not let any air back in.