Maybe to lighten up on this , pre filling the master piston space on a new install , with an empty system will put more fluid in sooner , especially the first depression , but all the lines and wheel cylinders are empty and still full of air , and there will be residual air in the lines in either the full or empty master case — you have to get that out . But if lines pitch up near master air will rise to high spots and mostly out during this fill process , air pushed back by its own compression , by partial displacement of air elsewhere by rising fluid in wheel cylinders , and , later in the process by shoes moving against springs . You see the geyser , right ? Lots of bubbles in master at first even after bleeding the wheels . The first stroke will push fluid out into the system — any air say in some other line or still untouched wheel cylinder will push air in lines back somewhat —restricted by residual pressure valves too. even if a drain is open and closed on one wheel ; why wheel sequence matters . Far away first . that stored air eventually gets out in the master if it can rise in lines near there or else trapped above fluid at the wheel . Why multiple smooth steady strokes are needed on manual bleed . . And sometimes rest periods with silicone due to entrained air , if all this causes local foaming . Pressure bleeders will avoid that return flow to master as flow is continuous and probably how factory does it . It takes a lot of fast flow to positively push the air ahead of fluid that way . . and possibly a lot of fluid. Probably captured and reused at factory . So Is it worth buying a pressure bleeder , related lid adapters etc and / or filling the master on the bench? —-as opposed to just part of the usual bleeding process ? —-this is up to the individual . The physics say air that can ,will rise up and out of master , but in the factory there is no time for all of that . But for most of us fixing old cars residual air has to be worked out by manual bleeding. —- stroking the pedal and it sometimes takes a while . I am not sure if how you start off will make any big difference in total time to removing the last sometimes difficult bit .
This is not saying don’t do it , —- it is advocating for it as critical to bleeding brakes, or the cause of bleed failure that I have some issues with .
I have never done master bleeding personally and eventually still get a good pedal. Taking off a master to bleed it and putting back on takes time and mess . Possibly can be done in place ? A trade against 3- 5 strokes of Pedal ? Your mileage may vary . That said it certainly can’t hurt . On replacing a master you can’t force much air downward into a full system , it will work its way out up through the master vent hole when you release the pedal . Air is introduced at the master ports when you swap out master bleed lines , it too works Its way up and out . Or you can crack those too under low pressure .
This is all hopefully taken by way of adding helpful information and promoting useful discussion among those interested . Not any kind of mandate or criticism . Decisions made , or opinions formed by understanding the issue better matter . The “why “ we do things does matter.
All is ok, obviously do exactly as you feel you want to , — knowing the why — and so understanding for yourself what is going on . Sent from my iPhone On May 11, 2022, at 2:35 PM, Keith Boonstra <kboonstra.zeegroup@xxxxxxxxx> wrote:
We consider it wise to follow the ways of the engineers and the original assemblers of our cars.
Can anyone confirm whether or not our M/Cs were bench bled before installation back in the day?
And what about today's assembly protocol? Are M/Cs bled before assembly on current production vehicles?
Keith Boonstra I will add that bench bleeding a master, as John points out is not essential, but not doing so will make bleeding the system take far longer, and, depending on the master you are working with, some must be bench bled to work.
Danny Plotkin
-----Original Message-----
From: "John Grady" <jkg@xxxxxxxxxxxxxxxxx>
Sent: Wednesday, May 11, 2022 9:57am
To: "dplotkin" <dplotkin@xxxxxxxxxxxxxxxxxxx>
Cc: "Mike Cortel" <toy72456@xxxxxxxxx>, "Chrysler 300 Club International" <chrysler-300-club-international@xxxxxxxxxxxxxxxx>
Subject: Re: {Chrysler 300} 300K Ram Brake Problems, air in brakes generally
You know This bleed the master stuff is repeated over and over as Gospel by people who read it somewhere .
Look at it — and tell me how air is “ trapped” in there when you have 100- 1000 psi pushing it to the obvious vent holes and then into the reservoir at the end of travel . The vents are on top of the bore (!!!!) .
Also also how fluid gets replenished, same holes . It acts as a pump , but it vents out top of bore at end of stroke.
Just like saying “air is trapped in a soda bottle as you fill it “.
Further , it is designed (!) to feed air up and out in the tiniest of volumes , when engineers made the thing . You ever look inside when you release brakes ? It shoots up like a geyser through the vent with return pressure as shoes move away .
In fact I think that action of the reverse flushing flow as shoes retract forces out any local air far better than any thing you can do playing on a bench .
And then you take off your bench bleed pipes and move it open ports to car ? Welcome in , air ! Fiasco in my opinion , do it if you want . Kind of like a rain dance . I never have , I believe what I can see , and I can see how it works inside —not a story on line .
However ,and related , sometimes you see loops or circles of brake tubing at the master in a vertical plane or an incidental upward U in tubing runs . Especially over rear axle . It is good to “ crack” that rear splice fitting open while under low pressure bleeding . That upward loop shape obviously can hold a stubborn air pocket Especially the vertical plane MC loops . About ten years ago I started putting the loops in a horizontal upward spiral if any loops at all . So air will naturally move up into the master and out , like any hydraulic system .
All this observation came from fighting with very early use (personally ) of silicone —- I put silicone so my wheel cylinders do not rust at the bottom like all 300 in storage will do with non silicone ( glycol ). That rust pit leads to a big surprise one day . I had that big surprise way back , as the wheel cylinder lip seal will transverse a rust pit one day . Out goes the brake fluid.
Or else change the gylcol completely every three years , as MB requires ( keep record of that) I Learned a 2000$ lesson thinking I knew better on a MB 300D way back , did not change it for 6 years , totaled all the antilock parts and rear wheel cylinders with rust pits inside , —as glycol aggressively holds water by design* .
If you don't drain it , it reaches a solution saturation level in the glycol sooner or later and then precipitates out as water in lowest place , All this is not arguable at all , but some will still argue . Can’t help that . Military uses silicone in everything as it is stored for years , and , re: boiling point , I am not racing my 300 , but I am storing it over the winter , where temp changes and barometric changes readily cause exchange of moisture laden air in the master . Water in the glycol boils at 212, too . Long before any glycol will boil. So high boiling point is irrelevant in our cars.
Also a very good reason for requiring an excellent seal situation on the master cover , why later ones are carefully sealed in rubber with a bail , with an expansion dome / bellows on top . Not a screw through a hole in cover , like our cars .
Just sayin…
Best , John
*I think why glycol was used , day one — instead of say hydraulic fluid or atf etc , —-but implies periodic service to remove the dispersed entrapped water . It is not oil.
Sent from my iPhone
Mike, a master is never shipped bled. You must bench bleed a master, failure to do so can make achieving a good pedal very difficult. Before I got sidetracked on residual valves I would confirm no air.
Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------
Date: 5/10/22 1:46 PM (GMT-05:00)
Subject: Re: {Chrysler 300} 300K Ram Brake Problems
Thanks, Dan, No warnings from the rebuilder. They did tell me that the MC had already been bled so I just installed it. I did order a Motive Bleeder system today.
Use an compressed air powered power bleeder. Remember that you should never over-stroke a master, easy to do while bleeding by foot, easy to blow the seal. Did the rebuilder give any warnings? Over-stroke a Treadle-Vac and its done. Did you bench bleed the masters before mounting? You can prove the master is good or bad by bleeding it & plugging it with the plastic plug they shipped it back with. If pedal sinks the master seal is blown. Otherwise I think you still have air in there.
Danny Plotkin
Rip, I bought one of these a few years ago and it's been one of my better investments. Just use a c-clamp to hold the top onto the master rather than their Mickey Mouse chain setup.
Thanks, John, Yes I do agree that having a second person at the pedal isn't the best method. We have had a few words ourselves :)
I believe I am going to look into a pressure bleeder as the first step. I have heard that the truck repair shops can be very familiar with this type of booster but Power Brake Exchange was a recommendation and at the time I was traveling to Pittsburgh for work.
Hi , it may sound crazy but having your wife in a tough position ( correctly using pedal ) can be part of it ! Been there , led to a , er, “heated discussion” . Long ago but still —-
Have to really understand the goal .
It is almost human nature to let up on the pedal a bit after doing what you say , after pushing smoothly down it can draw fluid or air back in —if timing of you at wheel cylinder drain valve and her at pedal is at all off.
Don’t laugh , happened to me.
In my case , add in silicone fluid a bear to bleed in the first place , if it gets agitated in the catch bottle or before you pour in you are done for .
I also agree — lacking any leaks ,— if pedal goes slowly down your master is not good. However on J,K you essentially have two masters .
They are a bear if booster not built right
. Competence matters . I tried myself with a kit , failed to get it right , someone had been in before me and I put it back together same way replicating a mistake they made .
The solution was discovering that these are common ( larger size vacuum can) on medium straight trucks . You can see them mounted on frame rail like gas tank .
A truck repair place knows all about them , in my case it was an International dealer. Put it in snd it worked fine after third try . I always had misgivings about those , but trucks by the millions use them .
J
In my entire experience, whenever the brake pedal slowly goes to the floor - after bleeding, etc, - it has always been a bad master cylinder. I don't know how old your m/c is or if it's been rebuilt, but if you can try another master cylinder. that may lead you to a resolution.
Also, the bleeding procedure you describe seems strange to me, but if the manual says to do it that way, then I guess that is OK. Generally, bleeding of the brake system always started with the farthest wheel cylinder (RR) and then the next farthest (LR. RF and finally LF). I do not understand why a 64 K should be different.
The bleeding was being done manually with my wife at the pedal and followed the order based on the service manual posted below. I did consider getting a Power Bleeder but again got frustrated and just parked the car. Any recommendations for a power bleeder? Thanks for the reply
Mike-
How are you bleeding? Manual with a friend on the pedal? Gravity? Power bleeder?
You have two circuits and need to rule out which one is the problem. I believe air is the problem and you want to know if its in the master or slave circuit.
Danny Plotkin
-----Original Message-----
From: "'Mike Cortel' via Chrysler 300 Club International" <chrysler-300-club-international@xxxxxxxxxxxxxxxx>
Sent: Monday, May 9, 2022 12:47pm
To: "chrysler-300-club-international@xxxxxxxxxxxxxxxx" <chrysler-300-club-international@xxxxxxxxxxxxxxxx>
Subject: {Chrysler 300} 300K Ram Brake Problems
A little background. Approx 2 years ago I was having leakage at the master cylinder and the brakes felt weak. I figured it was time for a rebuild. I removed both the master cylinder, the remote brake booster, and the slave cylinder and took them to Power Brake Exchange in Pittsburgh for rebuilding. They did find a broken spring in the remote booster and were able to replace it as well as the additional seals and such. They provided a test report and it showed the booster providing 300 psi? (I can not find the paperwork at this time but I believe that was the number.) I got everything back home and got back together. I also replaced the front wheel cylinders, shoes, and front hoses. Also, replace the vacuum line from the intake to the booster with the correct type of hose. I followed the service manual for the bleeding order of the system more than once.
Here is the problem. I have brakes when the car first starts up. But after a couple of stops, the brake pedal starts bottoming out and the brakes do not hold. I was so frustrated and fed up that I just put the car away.
In the meantime, I have become a cancer patient and I would really like to get this fixed and possibly enjoy the car this spring/ summer while I can.
I have considered taking the car to the local Chrysler dealer whose ownership is into Mopar Muscle as I am not sure how much I can still do.
Any thoughts or suggestions are appreciated as well as any shops in Ohio that may be able to work on this.
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