Bleed complete new system , stuck, 1986 wag

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Bakydnutbstr
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Bleed complete new system , stuck, 1986 wag

Post by Bakydnutbstr »

Replaced everything from diaphragm to wheel cylinders, bench bleed master cylinder, ok.
1st bleed backs . Two man method, pedal goes to floor when pumped, of course, backs done :) .
But pedal now travels only 2” and like stepping on a rock.w/o bleeding front.
I’ve removed front line from master cylinder and pumped fluid comes out of tube under pressure ( added tube back to master fluid recovery used finger as check valve ) but pedal only travels 2”to same spot and stops.
Would think pedal should travel to floor w/o fronts connected, (no resistance from calipers /closed system).
When connected to proportioning valve no fluids to calipers ( I read about pushing pin on valve or pull) but when I removed the feed line from master to valve pumped pedal like no fluids really came through, removed off caliper had some fluid in it but won’t pump out. My lines are all cuppronickel w ss stone guards.
Not clogged or blocked.
When bench bleeding master can push in no problem.
When in wag and pedal pumped travels bout 2” watching master cylinder as if it flexes upwards under pressure of depressing pedal, Help I’m stuck.
I’m 62 and done lots like my name suggests, it’s going to be nice this yr and I need to drive her.

SJTD
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Re: Bleed complete new system , stuck, 1986 wag

Post by SJTD »

You said you bled the rears ok so they're all done? The pedal shouldn't go to the floor now; it's only going to move until the front piston bottoms out. The rears are being applied and holding pressure as they should in a split system.

Open a rear bleed screw and it should bottom out.

That or I'm not understanding what's going on.
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.
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Bakydnutbstr
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Re: Bleed complete new system , stuck, 1986 wag

Post by Bakydnutbstr »

Yes pedal doesn’t go to floor so with backs done it should only go part way, it’s just I’m not getting any air out of front caliper passenger side once bleed is opened ,hold finger on it when pedal is depressed should feel air escape .
Like I mentioned there’s only bout 2” travel till pedal “bottoms out”
So I won’t get a full depressive stroke when front is being bled, only short travel 2” to purge air from front lines?
I also haven’t started it yet want it out of building first, new fuel lines, but want to stop, should it be running when bleeding fronts
I’ve never had such aggravation bleeding brakes.
Will keep trying,

SJTD
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Re: Bleed complete new system , stuck, 1986 wag

Post by SJTD »

Here's a weird theory for you. I don't know if it could happen and I don't remember if the forward half of the master applies the front or the rear brakes but for now I'll say the forward half works the fronts.

I'll try to use "forward" and "aft" to refer to the master and "front" and "rear" to refer to the brakes so I don't confuse myself.

So you bleed the rears. In doing so the forward piston gets pushed forward and sticks there. Now the bore behind it fills up more than usual and you get less travel because the empty forward piston doesn't move to waste some pedal travel once the rears are bled?????????

Or if the forward applies the rear brakes maybe the aft piston moves full stroke on its empty bore until the internal rod on it hits the forward piston and applies the rears. You bleed the rears but the spring between the pistons breaks or isn't there or they stick together for some reason. On the return stroke the forward piston moves too far back, the forward half the the bore overfills and now no stroke is wasted on the empty aft half of the master???????

I dunno if either of these could happen. Maybe the bleed ports in the master are placed so you couldn't get this "pumping up" of the rear brakes.

There's also the possibility that the master was assembled improperly. Reminds me of the time I put a rebuild kit in my Dasher. The spill port for the aft part of the master didn't get uncovered so as things got hot and the fluid expanded the brakes applied themselves. Don't remember the exact problem or why I was able to bleed them but it seems to me it was the bore in the piston that the rod from the pedal fit into wasn't deep enough. Long time ago.
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.
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Bakydnutbstr
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Re: Bleed complete new system , stuck, 1986 wag

Post by Bakydnutbstr »

Thank, my guess is problem is new master is defective but got it couple yrs ago cuz it’s a project more or less,
Have original and I know that worked for I’ve driven it and it stopped, with good pedal .
Will try to bleed again , if 😖 will reinstall old master.
Thanks SJTD
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tgreese
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Re: Bleed complete new system , stuck, 1986 wag

Post by tgreese »

New calipers? Last time I had a problem like this, I had a frozen caliper.

You can take the master cylinder apart and put it back together. Won't hurt it if you assemble carefully.
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itselliott
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Re: Bleed complete new system , stuck, 1986 wag

Post by itselliott »

I had a somewhat similar issue on a CJ 7..I installed the "big brake kit" (oem for a few years in the 70's) No matter how many times I bled the system, I had bad pedal pressure.....after several weeks of frustration, I realized that the bleeder valves were NOT at the very top of the caliper.....air was always still in the system. I had to remove the calipers and bleed them off the vehicle.......success!!
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Stuka
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Re: Bleed complete new system , stuck, 1986 wag

Post by Stuka »

Did you bench bleed the master cylinder? (Which can be done in the vehicle) In your description of what you have done, it was unclear. Its pretty important to do this before hooking up the front brakes. It will also let you know if the master just isn't working for the front reservoir.

From the sounds of it, either the front brake port on the master is plugged/non-functional. Or the proportioning valve is not dividing fluid to the front. When you bleed the rear brakes, did you have the button pushed in on it?
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bknblk
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Re: Bleed complete new system , stuck, 1986 wag

Post by bknblk »

I scanned the other replies and may have missed it. The distribution block ( on my 77 Cherokee) has a -don't know the technical name- not really a check valve that needs held in to help with bleeding the brakes. I've see two methods. Homemade metal clip on one of the mounting bolts or remove the idiot light pressure switch and install threaded plastic cone/plug the holds the plunger open.
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tgreese
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Re: Bleed complete new system , stuck, 1986 wag

Post by tgreese »

Combination valve. There is a section in the TSM about it. I don't want to repeat here what you can read there.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
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Bakydnutbstr
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Re: Bleed complete new system , stuck, 1986 wag

Post by Bakydnutbstr »

Thank you all for info.
Problem was proportioning valve moved internally and didn’t allow fluid to get to caliper's
Took apart made part to hold valve from moving finished task,that little device I made saved hours of agrivation
Fronts work great now
Thanks eveyone
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