Yes, I am finding that I have aged, I am now an idiot. 66 fury new brakes, master, wheel cylinders, shoes and some other small parts as needed....couple hold downs and cables. So, bench bleed with FIRST suggestion meaning the plugs....I will not do it that way again....lines back to the reservoir next time. But, great fluid and no air with cracking at master. Have bled several times at wheels, and adjusted the shoes to be pretty tight. So, what is happening now is one good pedal with great brakes, and then it will go half way down next time, unless I pump it. What I cannot figure is, if there were air in the master, it would be spongy from the jump, which it is not. Why one stop then crap. Also, if the shoes were not returning quickly enough, I guess this could happen with having too much travel maybe?? I have been thru this a couple times, repeating the bleeding and adjusting from the master down. No leaks. I am at the point that I wonder about the new master, and at this time if I go thru the cycle again, it will be with a new master cylinder. Just cannot get my weak mind to wrap around a great pedal once, then half way down with not much brake. This has now happened several times as I bleed, adjust and drive. Thoughts to correct my thinking appreciated. As I write, I think I may at least TRY to use the pedal and then give it time for shoes to return....I did note that the new wheel cylinders were a bit tight, but moved during the install.
Brake Gurus chime in please
- Thread starter 66furys
- Start date
You've got a leak somewhere.
I had something very similar happen. One of the cheap brake cylinders I used had a leak that wouldn't let fluid past, but would suck air in every time I pumped the brakes. Drove me nuts (short drive) . I found some good NORS wheel cylinders on eBay and replaced the brake cylinders.
It was hard to detect, I ended up plugging the front and rear ports of the MC and testing one at a time.. It lead me to the front of the car and that's when I figured out it was one of the wheel cylinders.
Somewhere, I think there's a good video on diagnosing issues like this. Let me see if I can find it.
I had something very similar happen. One of the cheap brake cylinders I used had a leak that wouldn't let fluid past, but would suck air in every time I pumped the brakes. Drove me nuts (short drive) . I found some good NORS wheel cylinders on eBay and replaced the brake cylinders.
It was hard to detect, I ended up plugging the front and rear ports of the MC and testing one at a time.. It lead me to the front of the car and that's when I figured out it was one of the wheel cylinders.
Somewhere, I think there's a good video on diagnosing issues like this. Let me see if I can find it.
I'm not going to recommend buying anything from this guy or say anything bad either. Reviews are mixed and that's all I'll say.
He does have a few great videos though and this is one that is worth watching. I think he talks about plugging the MC ports.
He does have a few great videos though and this is one that is worth watching. I think he talks about plugging the MC ports.
Appreciate the help, again. I can see your point that if the wheel cylinder were to return and suck air...Bad. I will say, that as I type, I have bled the system several times, looking for air. The only thing I have found in all of this is maybe a bubble....maybe. No air for all intents. But, will review your points and see if I can make sense. Thanks for points to keep me looking. Appreciate the help.
You have a leak someplace as noted. The chi-com wheel cylinders sometimes have poorly machined bleeder screws that do not seat properly. Same is also true for the line connectors. If the system is sucking air when the pedal is released, you should be also able to make it leak fluid. Have a helper keep pressure on the brake pedal and inspect the bleeder screws and line connectors for leaks.
Dave
Dave
rkrochen
Senior Member
This could also be a bad master cylinder. It wouldn’t be the first time I have seen this.
Check for leaks first as mentioned and if you don’t find anything you may have to try a different MC. These sort of things can be very frustrating to find.
Check for leaks first as mentioned and if you don’t find anything you may have to try a different MC. These sort of things can be very frustrating to find.
volksworld
Active Member
if rubber brake hoses have swollen shut internally fluid will have a hard time returning to the master although you can force the fluid through them while bleeding them manually
Justin Plant
Well-Known Member
Bad master has my vote. It doesn't have to leak to be bad. If you have a leak elsewhere, it should be easy to find.
Good points in the video. Thanks for the pointer. I wish he had expanded on what thoughts on a bad master that leaks.....which is where I am headed after about three cycles of bleeding with almost no air, good flow, and adjusting and re-adjusting the shoes....mine is all drum. But, after yesterdays rear brake work, I am ready for another road trip....and am just paranoid about the second and later pedals......have gotten one good one, then nothing. Back up and good, forward and bad. For the moment, I am going to use it a bit, even if it fails, and also try some time between pedal action to allow for a slow return of shoes.....just thinking. Then, if this continues, I am going to try new master, and will make the bleed tubes to bench bleed using that method, and not the plugs.
thethee
Senior Member
So you're saying you have one good pedal and then a bad second pedal.
What do you need to do for it to get a good first pedal again? I mean, if you wait for, lets say a week, does it return to a good first pedal on its own? Or do you still have to bleed it after that week for it to become a good pedal again? Under what conditions will it return to a good pedal?
What do you need to do for it to get a good first pedal again? I mean, if you wait for, lets say a week, does it return to a good first pedal on its own? Or do you still have to bleed it after that week for it to become a good pedal again? Under what conditions will it return to a good pedal?
rkrochen
Senior Member
If you are getting a good pedal some of the time and then suddenly a bad pedal I will reiterate that it is likely a bad MC. Air in the lines would result in a spongy pedal all the time.
No leaks, no fluid loss from master during all of this, plus checked at joints and lines. Do not really know what to do to check a rubber hose, other than visual. Pretty good shape...I replaced one front one but the new one no better, so have not done the other two. Good points all. Today, yet again, I head out and get full solid pedal the first time, and even by waiting a bit, the pedal then slogs down, low and a bit spongy. I can pump it up, which means who knows what. A loose set of shoes could cause the pump up, but I actually over tightened them, and then had to back off when the wheel stuck, so they are not loose. So, I am thinking that even though a pain, I will re-bleed the master with the tube/hoses, and re bleed the system before replace master. Crap.
Got your question on what or how long to get pedal back. It normally will be a day or so of re bleed and last time taking rear drum off for park brake, so there are both time and bleeding between these iterations....dont know if just sitting would cause this. Also, I agree with your premise on air and a good pedal....agree completely. Just can't get my mind to understand how a master could have an issue like this....maybe just move and have fluid go around the piston seal, and get fouled up.....then pump back up with some pedal. So far, no sense to me. I really appreciate your thoughts and points....make sure my old brain has not overlooked something stupid....which I am beginning to see now. I pulled the engine on my first car when I was 15.....and thought when I got this car.....no sweat, just the old simple stuff to work on. Not like the corvette C5 I sold last year, after plugs you cant reach, all kinds of electronic sensors to clean, check and so on, and some changes to the computers to remove some of the security systems that kill reliability. And yet, this old simple beasty is more trouble than all that on the vette. Oh well.
volksworld
Active Member
other than physically removing them and trying to blow through them there's really no way to spot a bad rubber hose...older style fluid would soften the rubber internally and swell it closed...while externally it looked fine...it got simpler to diagnose when i got a pressure bleeder...with only 20 lbs of air in the bleeder if you opened a valve up and nothing game out you knew a hose was blocked...but if they're still original they're overdue to be replaced anyway....another oddball thing to check is the parking brake...sticking or improperly adjusted cables could be holding the shoes against the drums and giving you a false adjustment with the cylinders having to travel too far....on cars that have driven me crazy in the past i've found bleeder nipples the same size as the lines and put unions on lines that had male ends and was able to just bleed the system without the shoes and wheel cylinders involved...then at least i'd know that the master was good...then hook one wheel at a time back up till i isolated the problem
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rkrochen
Senior Member
This is likely happening because the master cylinder cups are bypassing internally at times. I understand the frustration but you have done everything that will cause issues. At this point you’re overthinking the problem. Just change the master cylinder and move on to enjoying the car.
3C's & a D?
Senior Member
Then, if this continues, I am going to try new master, and will make the bleed tubes to bench bleed using that method, and not the plugs.
Are you saying that you bench bleed it with both ports plugged? That could very well be your problem. You need to have the tubes dumping back into the reservoirs.
Are you saying that you bench bleed it with both ports plugged? That could very well be your problem. You need to have the tubes dumping back into the reservoirs.
Thanks again for all comments. Yes, yes. But, the Raybestos kit says that the preferred method of bench bleeding, which is noted in lots of videos, is to use plastic plugs, supplied, and to first let sit to have fluid appear at the fitting, then plug, then add pressure to remove bubbles and have not movement of valve spool. But, I agree with your points now that that is likely a problem. Although I will add that I get no air at when I loosen the master line nut, AND there is no air bubble during return in the reservoir.....so I am thinking no air??? Also, one add here that I just found. I got a nice kit of SS line nuts for the brakes.....and now I find that MOPAR used a 9/16 x 20 nut.....noted in Big John video above. But the nice kit has 9/16 x 18 that dont fit......great. Just a point for future ref hereabouts. So now I try to find the finer thrd nut......betting auto parts will not have it.....did find ONE on amazon.....most are the 18 thd. Interesting.
3C's & a D?
Senior Member
I would avoid stainless fittings. If you do find the right ones, be sure to use anti seize otherwise you'll never get them off again.
I've never heard of that method, seems like more of a pressurizing than a bleeding. I would bleed it again, in place using the pedal. Just take off the top and two line fittings, install fittings with tubes and put it through the motions. Should take under 15 minutes to do. I've done it that way with success more than once. The new masters sometimes need a bit of breaking in. Then clean clean up fluid! Doing that way does make a small mess.
I've never heard of that method, seems like more of a pressurizing than a bleeding. I would bleed it again, in place using the pedal. Just take off the top and two line fittings, install fittings with tubes and put it through the motions. Should take under 15 minutes to do. I've done it that way with success more than once. The new masters sometimes need a bit of breaking in. Then clean clean up fluid! Doing that way does make a small mess.
Amazon had ONE site with a single fitting in the 20 thread....so have a couple coming. Cannot to this type bleed w/o the fitting. So, today again, I am testing. Sit in the car, and hit the pedal, again and again, always the same. Now this is subjective, but seems high and tight. So, down the driveway, and hit it. First hit seems to lock them up and again, high and tight. Second hit, the pedal SEEMS lower and softer, and the brakes will not lock up. Note, I am not measuring pedal height, or anything...all in my mind. So, am thinking of the mechanicals on the brakes, and the ONLY thing I found strange was the amount of force to move the new wheel cylinders....all pretty tight seals. And, used old springs.....even though I bought new ones....they seemed OK. My point is that something may be going on dynamically when you move, sitting still seems OK. So, while I await the new fittings, I will take it out, heat em up, and do some high speed stuff to see whaas up. Also, I always like antiseize on the brake line inside the fitting.....that is where I have seen problems.....rusting the line to the fitting and when you turn, you lose.
Hi. Don’t know if you have a brake booster, but I have a friend experiencing the same petal issue on an A body duster and it ended up being the booster has a vacuum leak. We could not tell. Also, a different time, depending on how built the motor is, and using the stock booster couldn’t handle the increase in vacuum. From what you described it sounded like the same kind of symptoms. Hope that helps.
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