Need help getting a firm pedal

[hunter92040]

I replaced the rubber brake lines and rebuilt calipers. Now I'm trying to bleed the system. I've tried both the one person method (Schwaben) and two person (Wifey).
Two person method: I get no fluid out of bleeder valve and a soft pedal.
One person method: I get fluid out of the valve.
Could it be my master cylinder needs replacing? I see no leaks from the MC.
Prior to the work, there were no major issues with brakes. The system was just old and I wanted to replace.
Any suggestions is appreciated.

[Jeff Higgins]

Frustrating, isn't it? I have found that whenever I replace major brake systems components, like the master cylinder, that traditional bleeding methods can be kind of ineffective. Or at least take a long, long time to get results.

For initial bleeding, I like to use a modified two person approach. Rather than have wifey "pump and hold" after which I crack the valve on the caliper (traditional method), I will open that valve on the caliper and have her slowly push the pedal to the floor. She then holds it there as I close the bleeder valve. We will do this half a dozen times on each wheel, being very careful not to let the pedal back up until the bleeder valve is closed. I always find this to pump a lot of air and fluid out. Be careful to keep an eye on the reservoir - this goes through the fluid much faster than the little farts we get with the "pump and hold" method.

Once you have done this, finish up with the old tried and true "pump and hold". I've always been able to purge the air this way, regardless of which component I've replaced.

[porsche930dude]

did you put the calipers on the right way? bleeders up

[911obgyn]

Put a 2x4 under the pedal so the cups on MC dont scrape over the un used rusty crust inside the master cylinder!

[Jeff Higgins]

Originally Posted by porsche930dude

did you put the calipers on the right way? bleeders up

Is it even possible to install them upside down? I guess I never thought about that. I suspect the fact that the brake line wouldn't reach might be a pretty ready indication all was not well, assuming we could even get that far.

[porsche930dude]

Im not sure about the 911 but alot of people manage to do it

[cabmandone]

If you've done a pressurized bleed and then with the helper you're not getting fluid out of the bleeders, you've got a problem up stream. Try a gravity bleed then go with pressure.

[hunter92040]

Thanks everyone for the advise.
Bleeders are up.
Sounds like the wife needs to pump slow and hold.

[911obgyn]

Thats what she said!

[David Inc.]

There is fluid in the reservoir, right? Maybe just the photo but it looks pretty dry.

If all you did was rebuild the calipers you shouldn't be having these issues unless you gulped air into the MC.

[Pedro '84 Coupe]

Possibly a silly question, but did you remember to crimp the vent hose or plug the nipple on the brake fluid reservoir?

[cabmandone]

Originally Posted by David Inc.

There is fluid in the reservoir, right? Maybe just the photo but it looks pretty dry.

If all you did was rebuild the calipers you shouldn't be having these issues unless you gulped air into the MC.

I'm glad you thought that too. I didn't want to be the one to ask. But each time I look at that pic I think... the reservoir is low.

[David Inc.]

Originally Posted by cabmando

I'm glad you thought that too. I didn't want to be the one to ask. But each time I look at that pic I think... the reservoir is low.

At a Lemons race once there was a team trying to deal with a stall and no-start issue and found that they weren't getting fuel pressure. They started to pull the system apart when one of the judges asked if there were any fuel left in the tank.

Anyway they were back on the road in no time. Sometimes the dumb question is the right one.

[hunter92040]

Thank you all for the ideas. The reservoir has always been (and is) between max and min lines. Please note, when I use one person method (with external pressure source) fluid comes out the bleeder valve. But when I do the two person method (relying on MC for pressure), no fluid comes out the bleeder valve and a non-firm (limp?) pedal.

[Bill Douglas]

Originally Posted by porsche930dude

Im not sure about the 911 but alot of people manage to do it

Who would be so silly

[ian c2]

Originally Posted by hunter92040

Thank you all for the ideas. The reservoir has always been (and is) between max and min lines. Please note, when I use one person method (with external pressure source) fluid comes out the bleeder valve. But when I do the two person method (relying on MC for pressure), no fluid comes out the bleeder valve and a non-firm (limp?) pedal.

She is pressing the brake and not the clutch ??

[Alexandphoto]

Recently had a similar issue. Minimal fluid coming out of the caliper furthest from the master and very soft pedal using the 2 person method.

I then (quite controversially) bled the caliper closest to the master cylinder to start, and immediately had a major improvement in feel and fluid in the system. I think it was just very empty lines due to replacing the master cylinder and one of the lines.

Might be an idea. Not sure if there’s any adverse impacts to doing it?

[Quicksilver]

If you have gotten air into the master cylinder it is WAY easier to first bleed the master. You just route a line straight from the outlets of the master back into the reservoir. (The end of the tubes need to stay under the reservoir's surface so you don't pull air back in.) Often it is surprising how much you have to pump it to get it to completely stop pumping bubbles.
After that when you bleed the whole system it makes it go a lot quicker.

[cabmandone]

Originally Posted by hunter92040

Thank you all for the ideas. The reservoir has always been (and is) between max and min lines. Please note, when I use one person method (with external pressure source) fluid comes out the bleeder valve. But when I do the two person method (relying on MC for pressure), no fluid comes out the bleeder valve and a non-firm (limp?) pedal.

Just to be clear, all bleeders closed you can pump the pedal and it builds pressure right? And once it builds pressure you're having your wife press the pedal while you release the bleeder until the pedal hits (hopefully you have a block to keep it from going full throw) the block. Then you're closing the bleeder.... normal two person procedure. But in your case as she's pressing the pedal you're not getting any fluid out of the bleeder?

Edit: What I meant above is, when you're in the car pumping the pedal, does it feel like it's building pressure at all? If not I think I'd pressure bleed again doing the normal right rear, left rear, right front, left front. If you had a decent pedal before you did the caliper you should be able to get a firm pedal again. Seems like you've got an air pocket stuck somewhere. I don't see anything mentioned in the work you performed that would allow air into the MC.

[Bill Douglas]

I put speed bleeders on the SC. They work well. It saves me having a falling out with the missus.