Pneumatic Brake Bleeder with Dual MC

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Ronald I. Maciejewski
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Re: Pneumatic Brake Bleeder with Dual MC

#16 Post by Ronald I. Maciejewski » Thu Oct 14, 2021 5:23 pm

Dave,

Thanks for the tip.

Ron
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Re: Pneumatic Brake Bleeder with Dual MC

#17 Post by Harlan Halsey » Fri Oct 15, 2021 4:05 am

While I take a dim view of dual master cylinders as being feel good items that are more trouble than they are worth, here are some pointers:

When using a vacuum bleeder: Run the clear bleed hose up before going down to the catch bottle. The hose will show bubbles coming from around the threads as long as you apply vacuum. So after bleeding a few ounces shut off the vacuum and observe the rising part of the hose. The thread leak air bubbles will cease, but the system bubbles, if any will not. Check for hard pedal. If not hard repeat until no bubbles appear. This requires a lot of up and down to refill the MC reservoir and check the pedal pressure. I did it for years using a Mityvac.

I now have a hand pumped pressure bleeder: Put fluid in the bleeder tank. Attach to the MC reservoir with the special cap. Pump to 10 lbs. The air space in the MC reservoir will remain as fluid flows around it. Bleed wheel one, no spurious thread leak bubbles will appear as the thread area is not under vacuum. When the bubbles cease, the line is full, move directly to the next wheel, etc. No need to check each wheel for hard pedal, and no need to refill the MC reservoir. Much less up and down and back and forth than with the vacuum system. But the brake fluid left in the bleeder tank has to be thrown out, and the tank cleaned and dried, so there is some wastage of brake fluid.

I usually flush the system with between half and a full one of the large bottles of fluid. In both cases, suck the MC reservoir empty and fill with fresh fluid before starting the bleed.

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Re: Pneumatic Brake Bleeder with Dual MC

#18 Post by Bill Oldham » Mon Oct 18, 2021 12:26 am

Everyone seems to assume leaks at the bleed screw (and spurious bubbles) using vacuum bleeder. I put grease around screws ( just squeeze a little grease on your finger and wipe around bleed screw). No bubbles except those coming thru system. Of course I do like the wife pumping the brake system best, but she is not always available.
I intend to try Al Zims bleed-leak method in the future. Hope it works because it's the simplest.

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Re: Pneumatic Brake Bleeder with Dual MC

#19 Post by Harlan Halsey » Mon Oct 18, 2021 6:11 am

It may be the simplest, but I would add 4 bleeder tubes with 4 catch bottles unless you want a mess. And then there's still a lot of up and down to keep the reservoir from emptying. Al probably has one guy refilling the master cylinder reservoir while another one runs around under the car shutting off the bleed screws. Doing it one at a time with David's cheap method, you can estimate the amount left in the reservoir by the amount in the catch bottle. But you have to de-pressurize every time you refill the reservoir. I consider the $150 I spent for the Schwerin hand pump well worth it. I try to flush my Dot 4 brake systems annually, but I have converted the 356s to silicone which I regard as permanent, and only check the reservoir occasionally.

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Re: Pneumatic Brake Bleeder with Dual MC

#20 Post by Ronald I. Maciejewski » Fri Nov 05, 2021 10:52 am

Hi Y’all,

My back finally “allowed” me to get to my brake bleeding. Following the K.I.S.S. principle, I decided to follow Al Zim’s gravity bleed suggestion but to do one wheel at a time instead of four simultaneously. I ran into a snag on the first wheel, left rear.

Filled MC reservoir, left cap off, opened bleeder no more than ¼ turn, and waited. Dripping started after a bit but NOT out of the end of the bleeder. The brake fluid was coming out at the bleeder threads and running down the back plate; not at all what I expected.

My concern is that some of the fluid is seeping into the drum and possibly onto the shoes especially since the bleeder is pointing up at a 45 degree angle.

I thought about greasing the threads but they are barely visible through the backing plate. I suppose I could just slap a glob in there but not sure it would help;

I suspect the same problem would occur with a pressure or vacuum bleeder.

Is this a problem or am I being overly cautious?

As always, thanks for your advice.

Ron
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Re: Pneumatic Brake Bleeder with Dual MC

#21 Post by DaveErickson » Fri Nov 05, 2021 12:16 pm

I had the same issue with a set of new brake calipers from Zim’s. I removed the bleeder valve (replacing it with a crimped off brake line that I keep in my toolbox). It turned out there was a circular piece of rubber inside the bleeder valve, and running a wire through the valve solved the problem. Grease can also plug the end

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Re: Pneumatic Brake Bleeder with Dual MC

#22 Post by Ronald I. Maciejewski » Fri Nov 05, 2021 6:09 pm

Dave,

Thanks. I`ll swap the bleeder with a one I know is clear. Easy fix, I hope.

Ron
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Re: Pneumatic Brake Bleeder with Dual MC

#23 Post by John Brooks » Mon Nov 08, 2021 3:00 am

Just watched a YouTube on this brake bleeder, pretty simple air cylinder and clamp system. Works the brake pedal system, on shop air for power. Remote control, It’s works like your wife, without all the complaints.

https://youtu.be/LP0nC1OFIxc
https://www.dtargetfb.com/index.php?mai ... _id=519508
Last edited by John Brooks on Mon Nov 08, 2021 4:28 pm, edited 1 time in total.
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Re: Pneumatic Brake Bleeder with Dual MC

#24 Post by Harlan Halsey » Mon Nov 08, 2021 4:26 am

There once was a fellow named Rube Goldberg .......

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Re: Pneumatic Brake Bleeder with Dual MC

#25 Post by Al Zim » Mon Nov 08, 2021 11:13 am

I am I have deleted my original post because it was not correct to use when installing a dual master cylinder. Rather than create confusion I recommend that you use the pressure bleeder for everything you do in bleeding brakes. al zim
Last edited by Al Zim on Sun Nov 21, 2021 11:40 am, edited 1 time in total.
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Re: Pneumatic Brake Bleeder with Dual MC

#26 Post by Ronald I. Maciejewski » Sat Nov 13, 2021 7:05 pm

Hi,

Bled brakes today per Mr. Zim's last post. All went well except it took forever to get clear fluid from the rears. Have solid half pedal so will adjust brakes again.

By the way, both rear bleeders were clogged so replaced them. The front cylinders are all new so no problem. The rears had been on for some time and professionally installed. On examination it looks like they were filled with grease from end to end; strange.

Hoping for a test drive late next week.

Thanks again, to all.

Ron
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Re: Pneumatic Brake Bleeder with Dual MC

#27 Post by Al Zim » Mon Nov 15, 2021 12:35 pm

Ron: they were filled with grease because they looked like grease fittings. The boss told the employee to grease the car. Something that the person NEVER did before.

I do the fronts and rears then check the master cylinder and top it off. After the bleeding I spray the backing plate with brake cleaner (NOT carb cleaner) to remove any brake fluid. This does not harm the paint. **revised**
Last edited by Al Zim on Sun Nov 21, 2021 11:44 am, edited 2 times in total.
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Re: Pneumatic Brake Bleeder with Dual MC

#28 Post by Ronald I. Maciejewski » Mon Nov 15, 2021 3:06 pm

Al,

Thanks. Never a dull moment.

Ron
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Re: Pneumatic Brake Bleeder with Dual MC

#29 Post by Dick Weiss » Mon Nov 15, 2021 4:19 pm

I never used a pnumatic brake bleeder during my 60+ years of brake work; I just use the existing (or new)
master cylinder using the pedal to bleed each bleeder fitting w/a plastic hose end submereged in a bottle
to prevent air entry when releasing the pedal followed by snugging-up the bleeder when the fluid is clear.
Just make sure the M/C reservior is kept full during the process.

Doing this work reviewing the rear cylinders (or calipers) fluid-flow, I use a long stick to press the pedal
several times until the above work is completed.

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Re: Pneumatic Brake Bleeder with Dual MC

#30 Post by Harlan Halsey » Tue Nov 16, 2021 4:35 am

Unless you like getting in and out of the car, balancing pusher sticks through the steering wheel, getting up and down and back and forth keeping the master cylinder full, spilling paint stripping brake fluid, or just enjoy the satisfaction of saving 100 bucks, get a pressure brake bleeder. Of course I didn't until my son brought his over and demonstrated it. Now we each have one.
Last edited by Harlan Halsey on Fri Nov 19, 2021 7:04 am, edited 1 time in total.

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