Bleed a Master under floor

I replaced all aspects of my brake system on my 53 poncho and was not able to get a good pedal feel after many attempts to bleed the brakes, I did bench bleed the master(single bore) before I installed it. I tried driving the car a little and the brakes completely failed, now I'm starting over with bleeding the brakes again.

What is the best way to bleed the master when it's in the car (i really don’t want to take it out as its a pain to get to under the floor)? When i got my master cylinder there was a note on it,” don’t bottom out when bench bleeding" whats that all about? I was careful not to bottom it out when bench bleeding but when bleeding the rest of the system I believe the pedal may have gone to the floor a few times.

Whats you're experience with speed bleeders?

Thanks!

Chris

 

use a power bleeder and unless your mc is bad that should work. lets see some pic's of your car.

 

I had to use a power bleeder to get all the air out of mine. You can make one or buy one from Jegs or Summit. Not a bad tool to have in your box, you probably won't use it much but its good to have just in case.

 

Thanks for all the input. I'm going to check the prices of a power bleeder.

-Chris

 

power bleeders are really nice, especially for those times that you dont have an extra hand around the shop!

 

I use a Mityvac II. It's a hang vacuum pump with a reservoir to hold the fluid. It works great and a lot cheaper than a power bleeder. Don't buy a cheap copy. You'll just end up buying the real thing. Don't ask me how I know. Start with the wheel furthest from the master and work closer. You'll get all the air out and you'll see it happening.

 

you might have a bad MC... its happened to me once or twice

 

Just went through the same ****. Brand new MC and it was a turkey. Changed it out and bled with a mighty Vac. I agree with Just Dug, get the name brand one. I also wont tell you how I know, (HF). Also make sure the pedal rod adjustment is set to allow full pedal return for complete recovery of the piston. In addition it is vitally important that the brakes be correctly adjusted. If they are not there is no way your going to get a pedal.

Just some stuff I know from experience.

 

When you guys got a "BAD" MC. What was the problem, seal torn, bore out of round? The MC for my car is exspensive and i've had it for awhile so i cant take it back; otherwise, I would be quick to swap it out.

I got a Mityvac. When i use this should i rebleed the master, or will creating va***e at the wheel cylinder be enough?

Thanks!

Chris

 

I do it like Moriarity does. I've had no problems.

 

make sure one of your wheel cylinders isnt leaking or ****ing air if thier new, i just had this problem the other day

 

Yep; good idea at this point being you are having problems,check all W/C for signs of leakage.If so pull it apart and have a look ,tipped/damaged cup etc.

 

you have a good person helping you with the bleeding?, i have had people who for the life of them can't understand that letting the pedal up is a no no till i get the bleed screw tight, i have a mighty-vac and i made a pressure bleeder from a garden sprayer.

 

I had an older gentleman tell me to "Gravity Bleed"???? the brake system. He explained to loosen all the bleeder screws on the wheels about 1/2 turn, take the cap off the master cylinder, wait till the fluid in the MC goes down a little ways, forcing the fluid through the wheel cylinders, tighten the bleeder screws, fill with fluid, replace MC cap, pump the brakes until you get pedal....I tried it, it worked!!!!
Anybody heard of this?

 

The problem with that is 1. It takes a while, and B. How do you know you have all the air out? the other 2 methods discussed work much better.

 

Make sure you have a residual pressure valve in your brake lines. I had the same setup and the same problem until I installed the rpv.

 

And my MC is lower than my WC.

I don't have a residual valve. Is this a must?

 

I was always told that if the MC is lower than the WCs then you must have residual pressure. Something like 5psi(?) for drums and 2psi for discs.

 

I agree, it does take much longer. I had to try it to ee if it really works. I still stick to the tried and true way of pumping the brakes, then releasing the bleeder screw.

 

I don't have a residual valve. Is this a must?[/QUOTE]


YES!

 

Gravity bleeding works well on a firewall mounted master cylinder.I always did one wheel at a time.
On old GM stuff with a under floor master and a screw on cap I use this; Take the cap from an old master cylinder,drill a hole in it,press in a 3/16 or whatever tube,seal with epoxy ,let it cure.Take a coffee can,drill a hole in the bottom,using same short length of tube,soldier or epoxy it. Then take the can, punch a hole(s) near the top,make a wire hanger and support it from the steering column or wheel.Screw in the cap with ****** into the master cylinder,attach a length of hose between the two.Partially fill the can with brake fluid,open a brake cylinder bleeder screw and let it drip for awhile,close it,go on to the next bleeder.Don't forget to protect the vehicle seat from spilled brake fluid and make sure your home made bleeder system is clean before using.........

 

do the same to a little garden pressure sprayer and you have a pressure bleeder , just remember to ONLY pump the handle 1 or 2 times so you don't blow your fittings on the spray can apart.

 

YES![/QUOTE]

So i take it i will put one in each of the three brake lines? My car did not have anything of the sort, but that dosent make it right.

How would i know if my MC has the residual valve built in? I'm running a factory replacement for 1953 Pontiac

Thanks!

-Chris

 

You only need the one in the master cylinder. BUT ya never know maybe somebody forgot to put one in when the cylinder was made. I think I would pull the cylinder off and make sure all parts are in it and ***embled correctly.