Need some help with Brake issues

Brakes for your Classic Mopar

  1. C2ndLTpigeon

    C2ndLTpigeon Mopar or no Car! FABO Gold Member

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    Well as the title states I need some help with some brake issues I'm having with my 73 Valiant. It has power brakes, front disc and 10 in drums in the rear.

    Decided to change the booster last week and discovered a leak in the rear seal on the master cylinder has a leak as it was leaking into the booster. I purchased myself a new unit from rock auto made by Cardone. Put it on a vise and bench bleed it. After spending a good amount of time on it I could not get the smaller section of the reservoir to stop shooting fluid from one of the holes could not tell where this air, if thats what it is, is coming from. I installed it on the car, blead the brakes drove it for a bit and every time I hit the brakes the oil light would come on and go off, see video below. Also while driving the pedal eventually became soft and pedal was almost to the floor before it started engaging. Now I do not have an oil light since the sender is gone and I rune a Oil pressure gauge. Its weird as it only started today after messing with the master.
    When I got back to check levels it sounded like the cap build pressure when I started to take the hold down off the master, it hissed. The level lowered in the small side and raised in the big side. Took the master of, redid the bench bleed, re blead the brakes same issue. Now I put the old one back on for now, chalking this up to a bad master out of the box.

    Old one bench blead, blead the brakes, and it seemed to do the oil light thing like the new one did, but seemed to stop after I added flued almost to the top. Before I filled it to the top it did the same issue with the fluid level, they where both the same level, drove it and checked, smaller side was lower and bigger side had more, filled them higher now it seems like some fluid is spilling out of the cap. Here's some pictures:

    Here is the issue with the oil light, odd, but after reading how the oil, and brake light is wired the similar, could this be something related to the proportioning valve?


    Here is the change in the fluid level after driving, both sides started at 3/4 full then the levels changed, the new master did this, and the old one (pictured) is doing the same.
    241284334_1585927248424807_1389613552598935171_n (1).jpg

    Master full to the top spills out:
    242117961_4273776692658112_5909575316391369774_n (1).jpg

    Here was the New master on the car, after bench bleeding for a long time using the fittings with hoses kit.

    Any ideas on the light? Prop valve? Is the fluid coming out of the master mean there is still air in there?
     
  2. BobW

    BobW Curmudgeon At Large FABO Gold Member

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    The surge in the reservoir is entirely normal, it's liguid not air. It has to do with the return.
    The drop in levels is not. You have a leak somewhere in the system, check your rear wheel cylinders.
    BTW, Cardone products are generally rebuilt, not new.
    The oil light issue is a wiring issue, you've crossed or misconnected something during the MC install.
     
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    • Joey4speed

      Joey4speed FABO Gold Member FABO Gold Member

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      Yep. Like Bob W says.
      The Brake light should be illuminating, not the Oil light. Separate wiring or connector issue. That may have always been crossed, but never faded the pedal to trigger the switch.

      As for the pedal fade, The core of the latest M/C could be bad, or the bench bleed connectors sucked air.
      Why don't you get your original rebuilt? DIY or ask around, That will correct the original leak.
      Nothing terribly tricky about rebuilding MCs or cylinders, but can be messy. Basically it's honing the cylinders and installing new rubber seal kits.
      Then check for leaks, especially at the rear brake cylinders, and bleed the entire system. (keep the rear drums on when pumping the pedal, easy to forget and blow the cylinders apart).
       
      Last edited: Sep 18, 2021
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      • Dana67Dart

        Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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        Unless as otherws have said you some how messed the wireing up to get the oilsender confused with the brake warning light. The oil waring light is telling you your ENGINE oil is low, or your bearing clearances are so loose tgat the engine can not keep 8 to 10 psi oil pressure at idle, or the oil pressure sender is bad.

        I have had that happen on my 120,000 mile rebuild on my 273. Oil light would come on everytime i came to a stop. I changed it for a new one, and now it only comes on if I let the oil get too low, like 1.5 to 2 qt low and i get off an interstate off ramp and come to a stop. Lots of oil up top and a little slosh and it sucks air and drops oil presdure to 0 for a second.

        I have since started checking my oil weekly, and using 10w-40 to help keep oil pressure higher.

        As for the small (rear brakes) resivour draining and the large filling, my bet is the new power booster needs to have the pushrod length adjusted OR ( and you power brake whimps :rolleyes: out there help me out here) if you used a master set up for manual it will have a pushrod keeper in the piston, and it MIGHT be interfeering with the power booster push rod, keeping the mc piston in the wrong place. (I am assuming that the power master does not use one, but im just speculating)

        The master uses fluid pressure from the large resovour to move the small resivour piston and if the pistons are not in the correct locations, ports will be uncovered and cause some of the symptoms you describe.

        As for fluid loss in the resivour if it is not leaking out past the cap, the rear of the mc, it has to be leaking from the fittings, calipers, cylinders or proportioning valve.

        Leaks are VERY traceable.

        If we look at this logically you had a bad booster. Prior to changing it your brakes worked fine, no funny master cylinder issues with braking (yes as you found out it was seeping at the rear). You changed the booster and the master and started to have issues, you put the old master on and have the same issues as the new master. The only part incommon is the booster.

        Get out your FSM and start reading.

        Good luck.
         
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        • Joey4speed

          Joey4speed FABO Gold Member FABO Gold Member

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          OP stated:
          "Decided to change the booster last week and discovered a leak in the rear seal on the master cylinder has a leak as it was leaking into the booster".
          Question is
          Not sure why he changed out the booster initially. ?
          Maybe because of fading brake pedal ? Or noticed brake fluid leaking into it?
           
        • C2ndLTpigeon

          C2ndLTpigeon Mopar or no Car! FABO Gold Member

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          I change the power brake booster because it was not functioning correctly after changing the booster I was still using the old master cylinder until yesterday when I got a new master cylinder since I did not want the old one to ruin the new booster because of the leak.
          I will do some reading up on adjustment of the pushrod. I also did some reading up and found out there may be an issue with the adjustment of the drum brakes in the back causing some air and for them to not believe correctly and that I should get the drums to barely drag and then try bleeding after.
          The master cylinder that I received is a little bit bigger but it is for a power brake front disc rear drum car.
           
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          • C2ndLTpigeon

            C2ndLTpigeon Mopar or no Car! FABO Gold Member

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            I did some reading and found out about the rear drums maybe the issue so I am going to readjust those, as far as the brake light I have a mess with any of the wiring and the oil light is disconnected and taped off and the prop valve connevtor is still on but I will double check. Still kind of new to brake systems so I was unaware that that surge is normal I had been thinking that it is air what is a good sign then the master cylinder is actually good so I will try to re bleed the master cylinder and go from there.
             
          • Joey4speed

            Joey4speed FABO Gold Member FABO Gold Member

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            Sounds like you're on track with the brake pressure.
            I have had luck with bleeding MCs while bolted to the car, with lines attached. Just by loosening the fittings then retightening before releasing the pedal.
            After that's done a few times, worked my way to the rear bleeders.
            2 issues with that procedure is
            You need a helper to press the pedal.
            Older brake fluids eat paint!
             
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            • C2ndLTpigeon

              C2ndLTpigeon Mopar or no Car! FABO Gold Member

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              This is the new master cylinder that I got from RockAuto they had two different ones, 20210918_090923.jpg 20210918_090918.jpg remanufactured and brand new so I went with the new one. It is listed as power brakes rear drum front disc is this correct?
               
            • Dana67Dart

              Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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              I'm jealous over your garage floor!

              it is a disc / drum from the looks of it, that's all we can say from the photos.

              when you say a little bigger do you mean physically bigger than the old one or the piston diameter is bigger?


              and can someone answer the question for me about the pushrod keeper in the cylinder manual vs power?
               
            • C2ndLTpigeon

              C2ndLTpigeon Mopar or no Car! FABO Gold Member

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              Thanks
              The unit as a whole looks bigger not the push rod part. I'll take a side by side pic later.

              Speaking of, is there a simple way to adjust the rod without a pushrod measure tool?
               
            • Dana67Dart

              Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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              You just need some streight edges and a caliper or a good mechanics rule. If you get it close youl be ok.

              Another way would be to adjust the rod a bit long, set the master in place, there should be a bit of force needed to make it sit flush. Then adjust the rod a half turn shorter and do it again. Repeat till you get to the point the master can be set in place without any force. you are probably at the correct spot.

              You could test the clearance with some (in know i know) lipstick on the end, thin coat. Assemble with the nuts and then remove and see if any of the lipstick transfered from the end of the pushrod. If it did it might be too tight.
               
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              • C2ndLTpigeon

                C2ndLTpigeon Mopar or no Car! FABO Gold Member

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                Going to try the lipstick idea the wifey gave me some she no longer uses haha.

                Here are the master cylinders, the smaller one is the old and the other new. The new one looks like a newer model, and looks just like the one on my dads 70 Cuda.

                I adjusted the rear brakes and will give the master a chance tomorrow. Really apriciate the help!
                20210918_205710.jpg 20210918_205719.jpg
                 
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                • RustyRatRod

                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  It's a good bit different, isn't it? That would have me wondering.

                  Also, I agree that it's likely somehow the two dash lights got reversed.

                  Lastly, if all else fails, gravity bleed the brakes. I've done that when nothing else will work and had good success. Actually, now its the only way I'll bleed one, unless it has ABS and "all that" hoorah on it.
                   
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                  • C2ndLTpigeon

                    C2ndLTpigeon Mopar or no Car! FABO Gold Member

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                    I readjusted the rear brakes, since I read it could cause issues with bleeding and I think I had them incorrectly adjusted when I did the 8 1/4 swap a few months ago. I looked at some of your old responses in the past about getting the wheel to almost make 1 rotation, this is what I ended up with in the video below, feels a little tight but makes almost a full turn.
                     
                  • Dana67Dart

                    Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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                    sometimes size does matter!!!

                    In this case you probably just have larger reservoir, assuming the piston is the same sizes as your oem unit.\

                    JUST to be sure... your rear brakes are fed from the smaller reservoir, correct?

                    can't tell from your video but if you can hear a faint scrap scrap as you turn it your there. rears are harder to adjust as the rear end puts a lot of drag on the ability to spin.

                    BUT it looks good to me.

                    BTW the rears ( assuming you have the adjusters on correctly) will self adjust if you apply the brakes moving in reverse a few times.
                     
                  • C2ndLTpigeon

                    C2ndLTpigeon Mopar or no Car! FABO Gold Member

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                    I would think they are if the brake lines go to the same ports on the master as the old one?
                     
                  • RustyRatRod

                    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                    I usually adjust them pretty tight. Tight enough you can turn the wheel but not loose enough it will coast much. The reason is because the rear braes have a LOT to do with the pedal height. The less they have to move to engage the drum, the higher the pedal will be. I don't mind if I even smell a little "hot" from the rear brakes on the first test drive or two, because I know they will have the least space possible between the shoes and drums. Of course you don't want them too tight, because they'll tend to heat WAY up and then just lock down. It's a balancing act to get them "just right".
                     
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                    • C2ndLTpigeon

                      C2ndLTpigeon Mopar or no Car! FABO Gold Member

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                      I think thats what I got, I can turn them like the vid, you have to give it a good spin, but its not a feather spin. Ill see what it does
                       
                    • Dana67Dart

                      Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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                      I agree but a quick trace out would not hurt unless the car has been in the family its entire life. it is easy to check start at the line coming from the rear by the firewall and it should go through one end of the brake warning combo valve to the small reservoir.
                       
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                      • Dana67Dart

                        Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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                        BTW you need to post some photos. that's a good looking car!
                         
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                        • C2ndLTpigeon

                          C2ndLTpigeon Mopar or no Car! FABO Gold Member

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                          Here's a few, had it for almost 2 years. 318 whiplash cam soon to be 360/408. Rust free CA car. Few dings here and there and the trunk was rattle canned before me. Overall good car.
                          20210816_125810.jpg 20210919_080645.jpg 20210816_125748.jpg 20210816_125926.jpg 20210627_190700.jpg
                           
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                          • Ricks70Duster340

                            Ricks70Duster340 Child of the King FABO Gold Member

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                            The larger master cylinder looks like the one I got for my '70 Duster 340 with manual brakes. I too got it from Rock Auto. I got one from them initially and it was the wrong one (was for drum/drum brakes). At least the one on the right is for disc/drum, but not sure it is for a power brake setup.
                             
                          • C2ndLTpigeon

                            C2ndLTpigeon Mopar or no Car! FABO Gold Member

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                            Here is the one I purchased on RA, look just like the ones that are listed as power masters on other sites as well.
                            image_2021-09-19_144211.png

                            Oreilly's looks the same, listed as Power brakes.
                            Screenshot (2).png

                            Napa listed as power as well
                            image_2021-09-19_143749.png
                             
                          • C2ndLTpigeon

                            C2ndLTpigeon Mopar or no Car! FABO Gold Member

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                            Still having issues, I have the push rod adjusted correctly. Bencj bleed the master again and bleed all the lines in order. Drove the car just down the street and checked the fluid levels. Rear resistor (front small) is lower then the other and the big ones level is higher.
                            3 out of the 4 lines bleed clean, the passenger front keeps letting small streems of brown rust like streaks after bleed quite a bit of times.

                            With the resiviour cap off with a slow pump of the brake pedal the front shoots fluid up (which I've been told is normal) but after the pedal is all the way down and I let off the pedal the back resiviour shoots fluid up too which I don't think is right and must be what is causing the fluid levels to shift.

                            If the oil light is really the brake light I think something might be wrong with the proportioning valve, this only starterld when I started messing with the brakes, something may have dislodged.

                            I'm at a loss hear, going to send the master back if I have too and order a prop valve.
                             
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