Tom454

It's possible that the "new" master cylinder is defective. These are old cars... and the "new" master cylinders sit on the shelf long enough to rust in the bore. After a few passes of the rubber seals over the rust, the MC fails completely. Just one possibility. I always disassemble "new" master cylinders before I install them and inspect the bore. Small price to pay. I then bleed the MC with tubes running from the ports back to the chambers. After that, I install plugs in the ports and test the MC. It should be hard as a rock. If it passes the test, then you are ready to start working on the rest of the system.

The "switch" is probably not centered. It will only go off center if there is a pressure difference between the front & rear circuits. It may have been off center prior to your new MC install. If you have no leaks between the switch and the calipers, the switch can/needs to be recentered.

Edit: Each rear caliper has an inner & outer bleeder. Bleed the inner first, then the outer.

arklacat

Will the brake light come on if the wire is not connected to the proportioning valve? If not, make sure the wire is connected. My dash light has never come on, but I just removed the old prop valve and the wire was not connected. Your proportioning valve (actually the differential part, if I understand it correctly) may not be centered and the dash light is just not coming on. just a WAG, i haven't even been close to a holiday inn express lately.

noonie

You've gotten good advice .
Start over and use the plug system.
With the master plugged, I've put enough pressure on the pedal (1/4" movement) to break the seat frame.
That's when you know it's a good master. They are hit and miss these days.
Then just go down the line and plug the next junction etc.

You shouldn't need it, but some people have used this little tool for the combo valve. It just prevents movement during bleeding. Cheap and might save you some headaches.



http://www.performanceonline.com/Com...ve-Bleed-Tool/

donyue

Hi Lemonchips,

Bleeding the brakes in our cars has proven to be a pain for me. After replacing the master cylinder, calipers, with Wilwood and rubber lines with stainless I tried to bleed the system manually many times with no luck. Finally got frustrated and purchased one of these bleeders online and within 20 minutes my brake system was better than ever with no air or spongy pedal. Best investment I've ever made. Made my own custom master cylinder cover with the manufacturers help. I'm not affiliated with the company at all, it is just a good product.

http://www.speedibleed.com/

calwldlife

sorry you are having troubles.
vet brakes are no different than other cars, just more bleeders.
I would have long since changed out/suspected the M/C.
As mentioned, hit or miss. Parts houses combining application
of parts to have less stock.
There are subtle differences in the pistons in the M/Cs.

get the wrong style and you get what you are seeing.

Been there.

edd gordon

I replaced the MC all four brake hoses. Rebuilt the calipers with oring kits. Installed new E Brakes and hardware. Started bleeding process with vacuum bleeder to get fluid moving and did nothing but gravity bleeding. System works fine. There are not that many parts on a C3 that can be a problem so I just replaced everything except the distribution valve. Old brake hoses make new problems. Good luck to all

Arkyvette

I replaced my master cylinder with a new Doorman from Amazon, all four brake hoses, the rear trailing arm hard lines and all four calipers. The system sat open for a month and I was worried with reading all these stories about bleeding. I Bench bled the master off the car first, then gravity bled the completed system for 48 hours while on jackstands with front end slightly elevated (helped that I had other work to do on the car) bled each caliper and I can lock up the wheels now. I would suspect a bad part if a system refused to bleed. I did have to slam the brakes a few times to center my prop valve prior to bleeding the rear brakes completely.

hugie82

I've gotten the check ball stuck in the proportioning valve and I pushed the pads back on the caliper to get it unstuck.
I think the trick is NOT too push hard on your pedal for bleeding! Slow and steady and don't go all the way to the floor. If your MC was bench bled properly, you can even crack bleeder screws and let gravity do the work until it drips out. Then start your bleeding.
Good Luck

TurboStitchCW

I think you are running into the same problem I ran into with my brakes. It's a matter of the calipers themselves being dry. That's what the problem is.

After bench bleeding the mc, I would connect it and nothing would happen and the mc would lose the prime. I found some plans online for a cheap DIY power bleeder using a garden sprayer.


its a Chapin #27010 garden sprayer with a 1/4" OD hose attached to the spray nozzle port since it it the same diameter using the bleeder fitting from my mityvac.

After some trial and error wirh sifferent methods, I thought about a thread over in the "General" section and though "why not pump up from the calipers to the mc"?

(this was with a completely dry system so gravity bleeding, vacuum, or pretty much anything else wasn't working)

So to start, I disconnected the rear "mc to proportioning valve" line, connected a hose and put it in a bottle so I didn't make any more mess. I connected the line (of my power bleeder) to the outer caliper bleeder (rears) and hooked a small hose to the inside bleeder and just had that one go into a plastic bottle to catch the overflow fluid. Once it was clear fluid, I closed the inside then the outside. Did this to the driver rear, then moved to the passenger rear and did the same except after I closed the inside bleeder, I pumped a few more times to build more pressure and went to keep an eye on the bottle at the mc. While waiting, I connected my mityvac to the rear port on the mc to prime it. As soon as it was a clean/clear flow into the bottle, grab a shop towel and connect it to the mc. Then a normal bleed and you're done with the rears. The fronts were no problem, so i just bled them normally.

Put my manual power bleeder together for the totally high price of $9.95 (sprayer) at sears, a couple bucks at lowes (hose), and the $20-ish for the mityvac (which is not really needed, just makes it easier).

Hope this helps if you don't have a Motive bleeder.

rand2527

Did you fins a solution to this, I have the exact problem


Thank you

Tom454

OP- 3/18/2012 fyi

JayRay

I used a vacuum pump to get them started and suck all the initial air out, after fluid started coming out I disconnected the hose from the vacuum and let gravity do the rest.

For Rand2527 with the current issue.

rand2527

Still no luck with bleeding. I'm using a motive power bleeder and get solid fluid when pressurized, will have a solid petal initially then get soft again, no apparent leaking. Only thought is air is being sucked passed one of the calipers but calipers are new.... I can plug the MC and all is solid, then clamp the flex lines and get a sold brake. open then lines and bleed again in sequence and return to hard petal then wait and it returns to soft after about 20 minutes. I can leave the motive bleeder connected for 24 hours and maintain 15psi... have no clue?? next is SS calipers I guess?

7t9l82

If if you don't have stainless steel sleeve calipers you're wasting your time

HeadsU.P.

A dentist once asked me if I wanted a root canal or bleed the brakes of a C3. Everybody knows which one is least painful. C3s don't like to be "pedal bled". You will trip the Proportioning Valve. Just went through all this last week. Buy the Prop Valve centering tool ($15) a vacuum pump tool kit off EBay, a master cyl bleeding kit and a 55 gallon drum of brake fluid.
What I learned: Bench bleed MC on the level for 15 mins in vise. Then nose down for 10 mins. Nose up for ten minutes. Take it slow, never go more than 1 3/8" in with the phillips screwdriver. Use a "C" clamp on the screwdriver as a stop. Otherwise you will roll the lips of the seal over in the bore and ruin the MC. Leave the bleed kit attached when you install MC on car. Then use brake pedal for one last stroke. Quickly hook up lines. Never, never, never let MC run dry or its back to the bench vise.
Old caliper piston seals can leak air in, but not one drop of fluid out. Put some antiseize on the bleeder screw threads to help stop air seepage when vacuum bleeding.

7t9l82

You guys sure get fancy to do something not that hard. Bench bleed the master. Fill it up have the car jacked up with the wheels off. Put an old tee shirt under each bleeder on the floor. Open the rear inner bleeder and the front bleeders.watch your fluid level.as full flow comes through a bleeder close it.when the rear inner flow close them and open the outers.make sure your hoses are good and you will be fine. It doesn't matter one bit which one bleeds first that's nonsense. Good luck.

HeadsU.P.

You can have "full flow" in your clear tubing and still have bubbles trapped somwhere.
Some manuals say outer first, then inners.

rand2527

I have come to understand that, I think the only was is to go SS calipers... I would like to get it dome with cast iron first to isolate the exact problem. I have done the outer inner procedure and used a mallet to rap the cylinders with no help. still clear fluid I agree the air is trapped in the cylinder just cant find a way to get it out. I can clamp the 4 flex lines and the petal is rock solid. That eliminates everything from the MC and the Prop valve and the lines????? I think the next is to remove the calipers and leave them connected and turn them to try and make the bubbled rise to the bleed screw?? what are everyone's thoughts.

Snoopysvet

Bleed using this sequence....

Left rear inner
Left rear outer
Right rear inner
Right rear outer
Left front
Right front

the sequence is odd but it will work

rand2527

I will try this new sequence today and let you know


Thank you