Rear Brakes Won't Bleed

[Scott 440 TNT]

Ok my 68 300 has power drum brakes, I replaced the MC and set out to bleed the rear lines.
I got almost nothing after pumping and nothing is coming through.
I'm thinking the proportioning valve has blocked the flow.
Usually there is some kind of way to reset the PV, any suggestions are appreciated.
FYI, I did bench bleed the MC and wheel cylinders are new with new rubber lines.

 

[69PHOENIX]

G'Day,
From Memory, and Please Remember I am getting OLD.
There should be an Electrical Switch in the Master Cylinder which is designed to: 1 Notify you of Lost Brake Pressure via a Dash Light & 2 Shut Down the Leaking Side.
To Reset, Normally Pulling the Switch & then Re-Inserting should Reset the Balance "Valve" behind it.
That "May" be the Problem.
I'm speaking about My Experience with Disc Brake 69 Plymouth type Vehicles.
The PV in your Vehicle may be in a Brass Fitting in the Line somewhere (Although I doubt it)
I could be wrong..... I remember the last time I was wrong, it was back in 1956 .... He rambles off into the Distance. LOL
Hope this Helps.
Tony.M
(Damn I am getting OLD, had to re-edit this Post 3 times before it made sense to ME.)

 

[Davea Lux]

The valve has a floating piston and with brake pressure it should reset itself. Check your travel rod adjustment. If that is ok, ChiCom MCs have been known to have the operating piston installed backwards. Check the brake line fittings at the MC, if there is an air leak there, the system will not bleed properly.

Dave

 

[Davea Lux]

As a follow up, the ChiCom wheel cylinders have a high defect rate from poorly machined seats for the brake lines and bleeder screws, if there is an air leak at either the system will suck air and not bleed. Same also true if the cylinder cups are installed backwards.

Dave

 

[69PHOENIX]

Hi Guys,
This question may be a Little off Subject.
I keep reading about Lousy Replacement Parts, for the Last Fifty Years here in the Mystical Land of OZ we have been Relining our M/Cyls & Wh/Cyls with Stainless Steel.
With Great Success. I have yet to hear a Club Member have any Complaints.
Is there some Reason why you Fellas don't do this sort of Thing?
Regards Tony.M

 

[Davea Lux]

Hi Guys,
This question may be a Little off Subject.
I keep reading about Lousy Replacement Parts, for the Last Fifty Years here in the Mystical Land of OZ we have been Relining our M/Cyls & Wh/Cyls with Stainless Steel.
With Great Success. I have yet to hear a Club Member have any Complaints.
Is there some Reason why you Fellas don't do this sort of Thing?
Regards Tony.M

It is a viable option to sleeve the MC and wheel cylinders, but its costs about twice as much as a ChiCom crap replacement, so a lot of people do not do it. There is usually enough replacement US sourced parts to avoid the China Crap.

Dave

 

[1970cat]

if it has a prop valve, sometimes they stick. try alternating pumping the brakes while banging on it with a hammer to free it up.

 

[69PHOENIX]

Agreed, It can be a Little Expensive, But it's one more thing you won't have to worry about for the Life of the Car.
The other point is that spares have not been readily available over here.
Disc Pads were running at around A$140.00 a Set. It seems that with Anything Different to the Run of the Mill, Payment needs to be extracted through the Nose. LOL
Thanks for the Reply, Tony.M
P.S. Has Anyone had Experience with the New Replacement Discs for the 69 - 71 Plymouths.
Some of our Club members have done 300,000+ Miles on the Original Discs.
Just wondering if the New Ones hold up as well.
Tony.M

 

[Davea Lux]

Agreed, It can be a Little Expensive, But it's one more thing you won't have to worry about for the Life of the Car.
Thanks for the Reply, Tony.M
P.S. Has Anyone had Experience with the New Replacement Discs for the 69 - 71 Plymouths.
Some of our Club members have done 300,000+ Miles on the Original Discs.
Just wondering if the New Ones hold up as well as....
Tony.M

The replacements are a one piece casting as opposed to a two piece unit. If they are properly made they seem to hold up reasonably well, the important caveat is that OEM style pads need to be used as many of the after market non asbestos pads are prone to causing excessive wear on any rotor.

Dave

 

[Scott 440 TNT]

Thanks for your feedback.
The MC doesn't have the low pressure sensor, it is located on the PV. I would love to remove the PV and do a thorough cleaning but I'm sure All the lines would break and I would be replacing all the lines :/
I'll pull the switch from the PV and hope I can get some flow going.

 

[69PHOENIX]

Davea Lux,
The New Discs are Selling over here for around A$300.00 a Pr.
Just wondering if worth shelving a Pair for the Future.
(An Aside: I am Amazed how your Brain thinks in Shorthand & if you're not careful it translates to the Page you're Typing!)LOL
The Other Point I'll mention is, it's a Good Thing they don't make us Post a Picture of Ourselves, I have been described as having the Sort of Face that Causes Old Ladies to Faint & Sends Children Screaming for their Mother. LOL
Regards, Tony.M

 

[boltupal]

Its very possible the reason your rear brakes wont bleed is.... The rear brake hose is shot. Get a new one at NAPA for 25.00 bucks.

 

[PH27L7]

Thanks for your feedback.
The MC doesn't have the low pressure sensor, it is located on the PV. I would love to remove the PV and do a thorough cleaning but I'm sure All the lines would break and I would be replacing all the lines :/
I'll pull the switch from the PV and hope I can get some flow going.

FYI, your car does not have a proportioning valve. It has a differential pressure switch; if there is any difference between the front & rear brake pressures, it trips a switch & your brake light comes on. My first thought would be your wheel cylinders, as mentioned could be improperly machined. You could disconnect at the cylinder & see if you're getting flow. As the man from Oz recommends, I sleeve original parts when possible, too many bad experiences.

 

[BIGBARNEYCARS]

Its very possible the reason your rear brakes wont bleed is.... The rear brake hose is shot. Get a new one at NAPA for 25.00 bucks.

If you're talking about the rubber line that drops off the steel line and goes to the spliter adjacent to the differential that feeds both back drums that would be what my first thought was - is. FIX? = REPLACE ALL rubber lines in the entire system on your 52 year old land yacht. When rubber lines get old they collapse on the inside with no indication outwardly, Jer

 

[Scott 440 TNT]

If you're talking about the rubber line that drops off the steel line and goes to the spliter adjacent to the differential that feeds both back drums that would be what my first thought was - is. FIX? = REPLACE ALL rubber lines in the entire system on your 52 year old land yacht. When rubber lines get old they collapse on the inside with no indication outwardly, Jer

A PO did some brake maintenance, i.e. brake cylinders and front rubber lines, I haven't looked at the rear rubber yet but I'll *** u me it is new also. I will confirm that today.
Thanks

 

[Scott 440 TNT]

Davea Lux,
The New Discs are Selling over here for around A$300.00 a Pr.
Just wondering if worth shelving a Pair for the Future.
(An Aside: I am Amazed how your Brain thinks in Shorthand & if you're not careful it translates to the Page you're Typing!)LOL
The Other Point I'll mention is, it's a Good Thing they don't make us Post a Picture of Ourselves, I have been described as having the Sort of Face that Causes Old Ladies to Faint & Sends Children Screaming for their Mother. LOL
Regards, Tony.M

It's my Wife's fault, she refers to BMW's as BM.
It's really a shorthand sickness. Lol

 

[BIGBARNEYCARS]

A PO did some brake maintenance, i.e. brake cylinders and front rubber lines, I haven't looked at the rear rubber yet but I'll *** u me it is new also. I will confirm that today.
Thanks

Assume iz the wrong A word. The one that your looking for iz Anticipate, never assume anything about what someone else haz done to a car you just bought, period. The rubber hose that drops off the under side of the floor pan to the rear axle is more often then not forgotten about 'cuz it ain't where the brakes are, DAH. Jer

 

[Davea Lux]

Davea Lux,
The New Discs are Selling over here for around A$300.00 a Pr.
Just wondering if worth shelving a Pair for the Future.
(An Aside: I am Amazed how your Brain thinks in Shorthand & if you're not careful it translates to the Page you're Typing!)LOL
The Other Point I'll mention is, it's a Good Thing they don't make us Post a Picture of Ourselves, I have been described as having the Sort of Face that Causes Old Ladies to Faint & Sends Children Screaming for their Mother. LOL
Regards, Tony.M

The supply of replacement rotors in the US is sometimes sporadic, like everything else as long as there is a demand, someone will probably keep making them. For what it's worth, I keep one extra set of rotors as a back up because I am a pack rat. My brain works most of the time, my fingers do not.

Dave

 

[Dsertdog]

I couldn't get my rear brakes to bleed.
Fluid would just dribble out.
Replaced the rear brake line. Couldn't blow air through it so I cut it open....

 

[Big_John]

Let's ask this question and work backwards.

Did everything work before you started replacing parts?