I attached the brake power bleeder and pumped it up only to find I get no brake fluid coming out of any bleeder on all four brakes. Went the conventional way of pumping the brakes to bleed. Same problem. Disconnected the front and rear feeds from the master cylinder and no brake fluid comes out from either port when pumping brakes. The master cylinder was new less than 1,000 miles ago. I attached the power bleeder to try and push fluid through - no dice. Any ideas?

Front and rear lines disconnected

 

Stab in the dark.

Is the fluid getting down the 2 hoses from the reservoir?? Odd, I admit, but stranger things have happened.

 

How does the pedal feel as you pumped it? Very spongy and no real "pump up", I would suspect a seal on one of the pistons in the master cylinder is backwards, missing, etc., or you're not getting fluid into the cylinder as Grant says. A hard, solid pedal would suggest something is plugged up internally. I'm assuming that the brakes have worked well during the last 1000 miles.
Dave

 

Grant - Yes I pulled the feed line plastic elbows out of the master cylinder and brake fluid poured out of them.

Dave - Yes spongy and no real pump up. However the only job I was doing here after brakes were really good for the last 1,000 miles, is replace the three flex lines. No disassembly of the 1,000 old master cylinder. So seals missing, backwards, etc is not the issue. I'm not saying the master cylinder didn't go bad, but I'm not sure how to test that theory, short of buying a new one and installing in its place.

 

OK, this will sound bizzare, but it worked.

1948 over P3. Hydraulic front, mechanical rear.

Like you, pumping away, rebuilt cylinder 8 months prior, and zero miles.

Tried everything I could think of, and in desperation, coz the master cylinder on them is as easy as spark plugs on a V12, NOT.

Filled the reservoir with Methylated Spirits (Metho down here), and let it sit over night. Since we use Metho to wash brake components prior to assembling, I knew nothing stupid would happen.

Next day, pumped away, still nothing, then something. Opened the 2 bleeders, and Metho came out, sweet. Filled with brake fluid, and gingerly bled the system, and it came up fine and stayed that way.

My thoughts were, and still are, something clogged the cylinder, and the Metho either dissolved it, or dislodged it, I never went looking, and the car was returned to the owner for trimming and painting. It was barn find of 30 years standing. He is still enjoying it today.

 

Interesting!

 

Here's my bench diagnosis. I pulled the master cylinder and put it in a vice. It was super difficult to push the piston in. And it doesn't spring back out on its own. With my past experience I'm thinking that's not normal?! I ordered a new master cylinder. So when I push with the pedal, it was probably staying pushed in.

 

Agreed.

Not your day at the moments.

 

It also explains why the past couple of times I drove the car, and what made me put it up on jack stands, was that when coming to a slow stop the car acted like the brakes were partially on. At first I thought it was the manual brakes being stuck. Now I know it was the master cylinder piston not releasing. Now that I've seen gunk in the master cylinder and the split brake differential unit (previous post), I'm wondering what other kind of crap is in the system. Definitely going to complete an entire brake flush when I install the new master cylinder. But I'm sure that at some point I should be taking apart the calipers for a thorough cleaning. But I'll let sleeping dogs lie for the moment so I can drive the car again.