Technical Mustang Master Cylinder Squirting

Hi all,
I have a 53 Chevy with a new Dorman master cylinder that fits a 68-72 mustang. I didn't bench bleed it before installing but I went through a few iterations of bleeding a few weeks ago. Last weekend I put new wheel cylinders and shoes on the 55 rear end that my 53 has.

I'm pretty sure all the air is out. I cracked the lines at the m/c and pumped the pedal a bit with fluid in the m/c. Then I bled the rear wheel cylinders.

When I step on the pedal there is a squirt in the rear reservoir only. It seems to be fluid only. Is this an issue? It leaks from the top of the lid as a result but if that is normal I'll focus on making the lid seal.

The pedal goes far down right now but I haven't adjusted the rear shoes yet as I had to leave my house for a few hours since my house is for sale and there is an open house. I will adjust the rear shoes when I get back and hopefully the pedal travels less. I observed no leaks in the system.

The only thing I wonder is whether the squirt is not normal. I did press on the pedal real hard a few weeks ago when I initially bled the system. I'm wondering if maybe that damaged something internally in the m/c making it squirt now inside the reservoir? I wanted to press hard and check the system for leaks.

 

the squirt is normal, the low pedal is from not bench bleeding, you must always bench bleed a new master cylinder or youll have a huge pocket of air in the system.

 

Why would you not bench bleed- it is not hard to do and makes bleeding the rest of the system easier.
Sometimes taking a short cut cost more than doing it the correct way.

 

Thanks the pedal didn't travel as far before I changed the wheel cylinders and shoes. The adjusters are all the way in. I'm guessing that's why it's traveling farther. I will adjust when I get back home. I bled the system and no air was coming out of the wheel cylinders after doing it for quite a while while continuing to put new fluid in just to make sure

 

It didn't come with the bolts/plugs for the ports and I was trying to get the car movable one night a few weeks ago since I was blocking the water heater and a buyer's inspector was coming the next day.

What should I do now? I cracked the lines at the m/c and pumped several times and fluid was coming out then I tightened back up. Then I bled the wheel cylinders. I'm wondering if adjusting the shoes will bring it back to normal or if I have air in the system. It doesn't feel like it since I bled for a long time well after the initial bubbles of air came out from The bleeders. No additional air was coming out.

 

You can get something like this to bleed the master cylinder.
http://www.summitracing.com/parts/rnb-13910?seid=srese1&gclid=CK2P3bTzycUCFZY0aQodrFcAuw

 

bleeding brakes w/o a pressure bleedr or a vacuum bleeder is not a 1 person job , from the sounds of it , you're trying to do this alone ..
dave

 

Yes I am doing it alone. I have a tool that has a check valve at the end and a plastic hose you hook up to the bleeder. I put the hose and check valve above the bleeder In height and secured with twisty ties and I can watch all the air bubbles rise after I pump the pedal a few times just to make sure it's working. I did this for several minutes on each bleeder and checked only fluid was coming out. I went through excessive brake fluid just to be ultra sure

 

Thanks I will keep that in mind. What should I do now? I had installed the m/c a few weeks ago and it took me nearly an hour to get it to accept fluid and then I bled everything for a really long time. I drove it and it felt fine. I decided to do the wheel cylinders and shoes last weekend so I would have to bother with brakes for a while.

 

I bleed my brakes by myself all the time with a One Man Brake Bleeder from NAPA. Harbor Freight sells the same one.

 

Does the bore size of the new wheel cylinders match the old ones?
Are the new shoes the right ones and are they mounted correctly and properly adjusted?

Any time you hook something up to a bleeder screw like the plastic hose with a check-valve you run the
risk of sucking air into the system. The air can enter through the bleeder screw threads when the pedal is
returning. I haven't had good luck with reverse bleeding for that reason, even when I used teflon tape to
close up the threads.

You can bend a couple of pieces of brake line with fittings attached and hook them to your MC ports,
with the open ends of the lines going into each MC reservoir, then bench bleed using the pedal arm.

Good luck.

 

the squirting fluid is caused by air in the system that becomes compressed and when the pedal is released it forces the fluid back to the M/C with enough force that it squirts out. I suspect the check valve you're using is introducing air back into the system

 

The rear shoe adjustment will bring up the pedal quite a bit. I've even tweaked them a bit too far for bleeding and back them off a few clicks after. I did my Ford after the disc conversion without bleeding the master, I used a vacuum bleeder and the pedal is great.

 

Thanks, I adjusted the rear shoes and the pedal doesn't seem to go down as far now but I need to bleed again most likely. It doesn't feel as firm as it used to right now.

 

Thanks, I'm going to check all these things. I'm pretty sure the wheel cylinder bore size is the same and the shoes are also the same that were on there before.

 

Thanks, do you think something like this would work?



http://www.napaonline.com/Catalog/C...l-Hydraulic-Systems/_/R-BK_7001008_0361146609

 

I have always bled brake systems in this way;
I get 4 half-full (optimist) containers of clean brake fluid. I place one next to each wheel up on a block. connect a plastic or rubber hose to each bleeder and crack it, place the hose in the container (close pin works to hold it there). Loop the hose so it is higher than the drum or caliper (masking tape works to hold it up).
Slowly cycle the brake pedal, checking every other stroke to ensure that the containers do not empty or overflow....

I have used this method for many years on all kinds of hotrods and race cars - it ALWAYS works, also has the benefit of pushing out nasties (which sink into the container), and sucking in clean fluid - remember, cycle the pedal slowly !!!

JD

 

Thanks, is there still a possible issue with the bleeder threads and air getting in through there in some rarer cases?

 

Nope, not if you cycle SLOWLY, the minimum amount of pressure and suction keeps it sealed, like I said, this is a pain in the butt to set up, but it always works - even did it on an ancient forklift recently, pumped out a ton of crud, after doing it, the warehouse guy asked me who put new brakes on the lift ??? lol

 

Thanks, do you think my technique is worthy if I cycle slowly? I do each individual bleeder with the plastic hose and the check valve placed above the height of the wheel cylinder or caliper. I crack the bleeder just barely enough that fluid can go out with light pumping (not by gravity). I don't see air bubbles travel back down into the bleeder but I do see them being pushed out. I'm not sure if I can suck air in when depressing if I cycle slowly? I can also try your technique too.

 

I think your technique could work, but I think often you end up cycling a bubble back & forth... The value of having the end of the tubing submerged is that bubbles escape, then when the pedal is retracted, it lifts clean fluid into the system. I have used this successfully on 30's coupes with the MC under the floor, dirt track cars, my drag truck, you name it, it just works. Takes a while to set up, but I sware by it...

 

Thanks, I think I may try this out for sure. It's best to do the two wheel cylinders and front calipers all at the same time?

 

I forgot to ask, if there is some air in the master cylinder should I try a vacuum pump tool instead? It's possible there is some stubborn air in the M/C, im not sure. I had installed it without bench bleeding even though I went through many bleeding cycles with the rest of the system. My guess is I got most of the air out of it but I can't rule that out.

Right now the rear reservoir squirts when pressing the pedal down. I wonder if I damaged anything in the m/c. I had pressed on the pedal hard to test for leaks but it was filled with fluid. Yesterday I cracked one line and pumped a few times with my hand but not sure if my strokes could have been too long. hmmm.

 

I disagree with your theory. My notion is that the 'squirting fluid' comes up through the small port in the base of the reservoir to master cylinder bore that serves to fill the bore with fluid when the piston is retracted. The port is a little bit ahead of the piston when it is retracted and when the brake is applied the fluid is pressurized and fluid escapes the M/C bore until the piston cup passes the port. At that point the piston is producing pressure that goes to the wheel cylinders and/or calipers to apply the brakes.

Ray

 

Thanks, before changing the shoes and wheel cylinders I remember the rear reservoir having a squirt when I let off the the pedal. Now (after bleeding) I am seeing it squirt as I press the pedal down. Weird.

I'm thinking of getting a piece of tube and a big syringe from a pet supply and pressure bleeding. That should get any suspected air out the M/C since I didn't bench bleed long ago right?

 

I realize it is Holy Gospel here on the HAMB to "bench bleed" master cylinders.......but I think more is made of that than it deserves. Yes, it is helpful and easy to do. But if not done, it is not the disaster some here make it sound like. Any of the conventional bleeding methods mentioned in this thread will get the air out.

Often, air isn't the entire cause of a low pedal problem. Brake adjustment is equally important. That has been mentioned and you have indicated awareness of that. With careful and patient bleeding you should get the pedal where it belongs soon.

Ray

 

Thanks when I adjusted the shows it felt like the pedal was not low anymore. I've bled the system a few times but the squirting as I press down made me think there is still air in the system. Regardless I'm wondering if the string method is good to try just in case a stubborn air bubble is in the m/c. Before I did the shoes and wheel cylinders it felt ok but occasionally I could pump just a little and feel the pedal just a tad bit firmer but not by much. Maybe my method was getting small amounts of air in the bleeder threads. This is why I'm thinking maybe a syringe and back bleed the system.

 

New shoes will not feel the same at the pedal. They need lots of miles to seat into the drum, unless the shoes were custom fitted to each drum.

I suppose you did not set the shoe into the drum, to see if the curves matched? If the shoe rocks like a rocking horse in the drum, then it will be a soft pedal, because the shoes are actually flexing, trying to conform to the larger diameter of a worn or remachined drum.

Take the car for a normal 2 mile ride, then feel for heat at all 4 brakes. If one end of the car is cold, those ain't working

 

l

Thanks that is great advice. Right now I want to bleed with the best 1 person technique so I can rule out air anywhere especially given that I didn't bench bleed the m/c a while ago. It seems the syringe approach is the best one. Maybe next weekend I can get someone to help if I don't try that before. It's possible I have some lines above the m/c making the pressure bleeding via syringe a better idea

 

I would just see if you can get someone to come over and be the pedal pumper.
It would probably be alot easier and less of a headache. I'm just to far away otherwise I would help you in a flash, sorry.