Bleeding Brakes

[Steam Driver]

Let me start by saying I have read the Pelican tech articles on this, and I'm no stranger to doing it anyway. But I've run into a perplexing situation. I think I know the answer but hope it's not the right one!

The car is a 1982 SC. When I first acquired the car it had been inactive for about 12 - 15 years. So one of the first things I did was to do brake maintenance. I rebuilt the calipers and installed a new master cylinder. However at that time I did not fill and bleed the system, which was probably a big mistake even though it seemed like a good idea at the time. Life interferes with the best of plans and that was now five plus years ago.

So the last several days I have been trying to fill the system and get it bled before reinstalling the power train. I am using the Motive Power Pressure Bleeder, but using it as an air reservoir only, with fluid only in the system So far I have put about a half-gallon plus of fluid through the system and "think" I have all of the air out, but still no pedal whatsoever; not a hint.

I'm thinking that the new M/C might have gone bad from sitting all that time with no fluid, although I would have thought that during the manufacturing process there would have been some pickling lubricants involved.

Anyone else ever run into this?

[lsf911]

I have run into this problem just recently.
Did you bench bleed the master cylinder before you installed it? If you didn't there is air trapped in it and will cause your symptoms.

[gwmac]

I also had this problem, Bled with two people the old fashioned way and it cured it right up. Takes a lot of volume to carry the air away from the MC

[Bob Kontak]

Originally Posted by lsf911

I have run into this problem just recently.
Did you bench bleed the master cylinder before you installed it? If you didn't there is air trapped in it and will cause your symptoms.

I agree.

I don't have my 81 in front of me now to check but I have bled master cylinders with Motive and the buddy system. Just crack the line nuts at the cylinder and perform the procedure as if they are bleeders.

[shadowjack1]

Seeing that rebuilt the calipers, did you install them with the bleed screw up?

[Steam Driver]

Oh yes, Calipers installed right.

I have never had to bench bleed an M/C on anything before, and even if I had it was probably too long ago to be valid.

As to breaking the lines at the M/C and treating them like a bleeder, I trust something goes under the M/C to account for the fluid lost.

I will also go back to the old reliable two-person technique that has always worked before. This is the first time I've tried the power bleeder; so far I'm not impressed with it's being better or easier! I've been messing (literally, considering brake fluid and all) with this for several days now.

[RedCoupe]

I had one instance where ONLY bench bleeding the MC would make the system work, so now I always bleed the MC first before going to each caliper. Yes, you need to rig up something to contain the brake fluid mess. But, you will get this solved! Also, in the past I have found that starting the engine can help as the booster will give a bit more stroke to the MC piston.

[icarp]

bench bleed the MC , it is a must

[CCM911]

You could also try a gravity bleed to get things started. Just open the right rear bleed nipple until fluid starts to flow. I do this on my motorcycles all the time.

[Steam Driver]

I tried a gravity bleed and practically nothing flowed. I found that surprising. The lines are open though, as the pressure bleeder pushes it through fine,

[roper0621]

If you are using the Motive Pressure unit, don't forget to block off the overflow tube, please don't ask me how I know this.

[Steam Driver]

Oh yes, that is blocked off.

[Jesse16]

I replaced my MC long ago on the 87, reason being a soft pedal and and re-filled the system using a motive. No special filling of the MC and I got the pedal back reasonably easily. I agree with the person who talked about pumping the pedal which you have done and still no pressure. If you've pumped the pedal and you've got fluid moving from reservoir to the calipers and its not leaking out somewhere or a brake hose isn't swollen/bad and still not generating pressure then it sure seems like a bad MC.
Pretty simple and relatively low cost to install another. After you pump the pedal, can you ever notice any air or sputter as a caliper bleeds ?

[CCM911]

Do you by any chance have a MityVac? This would allow you to "pull" the fluid through the system.

[David]

I changed the MC on my 930 a few months ago. I did not bench bleed it and it bleed very easily with just a Motive bleeder. Something seems wrong with your system

[djpateman]

It is not always easy to get the caliper outside pistons filled. Rapid pumping of the brake pedal may start to build pressure/resistance, but be careful since it has been recommended not to push the pedal all the way to the stop; with a new MC this be less of a problem. I also prefer the suction method compared to the pressurized method. But I always finish with pedal pumping; this this creates smaller and more mobile bubbles. I will often reuse clean fluid until I get a solid pedal, and then finish with fresh fluid. You also have to ensure the reservoir never runs dry or air will be reintroduced.

[Rawknees'Turbo]

No need to play around with a Motive pump bottle, vacuum pump, or bench bleeding of the master cylinder (which is definitely not a "must", contrary to what was stated a few posts above) if you have an air compressor - simply attach an air gun to the res vent nipple with a suitably sized hose (fill cap on res - can wrap a rag around it to catch some slight fluid mist that might get by the cap if the air pressure is a little too high), set the air pressure regulator to about 15-17 PSI and control the on/off airflow with the gun's trigger (add fluid to the res when the level reaches your personal, low comfort zone). This is a one-person operation that quickly purges all trapped air from the system. I use a strip of Velcro to hold the trigger down as I go check whichever caliper I'm working on - a rubber band works, too.

[Stevepro]

Try adjusting (shortening) the pushrod from the peddle into the back of the master cylinder so that the piston in the MC is retracting fully and there is a tiny amount of free play between the pushrod and the MC piston.

[Evans, Marv]

OK. I had pretty much the same scenario with my brake system. I installed a new MC and let it sit for several years thinking it would be fine when the time came to fill it. When that time came, I couldn't get any fluid past a small amount to flow. I finally took the master cylinder off to find the intake holes the hoses from the reservoir connect to were rusted shut. Solved the problem by installing another new MC. I would have been better off filling the system with fluid but would have probably even had a problem of some kind from letting it set for so long.

[Steam Driver]

I haven’t readdressed this issue yet. But it baffles me how I can be getting fluid with no bubbles at all four wheels but zero pedal. Obviously the pressure bleeder is pushing fluid through the M/C, so nothing is plugged.

Another thing is gravity bleeding. I have tried this, after I had achieved no bubbles in the fluid with the pressure bleeder, and NOTHING comes out. Go figure that!