Brake proportioning valve giving me trouble, options?

[Arctic Donkey]

I completely replaced the braking system on my 71 Challenger. New M/C, new proportioning and meter valves, new hard and flex lines, and new calipers and wheel cylinders. Went to bleed the brakes at the passenger side rear and couldn't get a drop. Tried pumping the pedal and using a mity-vac to pull the fluid through.......nothing. I wasn't aware of a proportioning valve bleed tool and suspect that the differential pressure valve inside the PV has shifted.

I am about to take it off and try to manually re-center it but I do not have the tool and can not get one within the time frame I have. If I re-center the differential pressure valve (DPV) and hold the rod on the bottom of the metering valve open (out) will that be enough to stop the DPV from moving each time I try to bleed? If not, is there another option if I don't have the tool?

This is the tool:
https://www.summitracing.com/int/parts/clp-pv-tool

[1 Wild R/T]

That tool is for GM valves.... Doesn't  fit Mopar.... I own a much older version thats made of steel....

Most of the reproduction proportioning valves are junk, if it came from Inline tube, it's virtually guaranteed to be junk...

For the valve to be pushed off center you would need hydraulic pressure on one side (Half the system fully bled & holding pressure....

Personally on a new system I prefer to use a new oil squirt can & a short length of hose, I push fluid from the bleeder screw back to the M/C...  Works extremely well, typically I have the whole system completely free of air in less than 15 minutes...

[Arctic Donkey]

Great information, thank you. The proportioning valve was from Summit not Inline Tube (my lines were from them). This thread is my exact situation, down to buying the car in my teens then storing it for 30 years....followed by a complete replacement of the brakes. In the thread they mention making a clip to hold the "rod" on the bottom of the metering valve out. What purpose does this serve and should I be doing it too?

http://www.cuda-challenger.com/cc/index.php?topic=116766.msg1145398#msg1145398

I watched a video of someone doing as you suggested, pushing the fluid in at each wheel. I will try that after I diagnose whether my new proportioning valve is any good. On my old one, if I blow air into the outlet port for the line that goes to the rear brakes I get air blowing out of the port that is directly opposite it, this is the port that is fed from the small reservoir of the M/C. On my new proportioning valve if I blow air into that same port (outlet port for the rear brakes) it is blocked. Will try taking that nut off of the bottom and see what I can see.

[1 Wild R/T]

The tool is pulling the brake hold off valve open.. Fluid should travel from the wheel cylinder back to the master without restriction.... The reproduction proportioning valves have a tendency of the spool valve to be slightly to big & it binds in it's bore....  If your original valve is for disc brakes I'd disassemble it, clean it & reinstall it.... I've done that many times & never had a issue... Reproduction parts rarely work as well as a reconditioned original part..

[Arctic Donkey]

My car has power discs up front and drums in the rear. The proportioning and metering valve assembly that I got from Summit looks identical to what was on the car but I have no reason to believe that mine were faulty, just chose to replace them while I was doing everything else. After sitting for 30 years, I think the real problem(s) was in my flex hoses. Two of the three were blocked.

I'll clean up my original valves as you suggest and see how that goes. Do you always keep that hold off valve open when you reverse fill your fluid?

[1 Wild R/T]

No, the fluid should flow to a master cylinder unimpeded... Actually it should flow in either direction till you actually have a fully bled system... Then it slows flow to the rear till a preset pressure is reached at which point full flow to the rear brakes is allowed...  By slowing flow to the rear brakes it helps reduce rear lock-up & the fun ride that follows...  On normal braking it doesn't have much impact but on hard stops the front brakes grab first & the rears are delayed slightly...

[Arctic Donkey]

Thanks for your help. Will report back.

[Arctic Donkey]

I took apart the Summit PV and found that the tip of that brass "bullet" with the two o-rings was covering the inlet port from the M/C for the rear brakes. Once I put it back together the port is no longer visibly blocked but I still can't blow air through it, I can blow air through the one that was on my car. From the outside the new and old PVs look pretty much identical but as you can see they use a different internal design.

[Arctic Donkey]

I couldn't get the Summit proportioning/metering valve assembly to work so I cleaned up and reinstalled my old one. I bled the brakes by myself with a Mityvac but wasn't happy with the results. Got someone to sit inside and "operate" the brake pedal and we quickly got the remaining air out of the system.

[1 Wild R/T]

Glad you got it fixed... Sorry to see reproduction valves are still junk....

[Arctic Donkey]

Thanks again for your help. After reading various articles I was convinced I needed that "PV bleed tool". As it wasn't available locally I would have spent a bunch of money rushing something I didn't even need.