Gary Lewis Posted September 30, 2019 Share Posted September 30, 2019 also no brake fluid is leaving the valve to go to the rear I'm confused. Were you able to bleed the right rear with one of the valves? If so, brake fluid has to have been coming out of that valve then. Do you still have that valve? If so, put it back on as it is good. Then we can troubleshoot why the driver's side wouldn't bleed. Link to comment Share on other sites More sharing options...
snakebite8 Posted September 30, 2019 Author Share Posted September 30, 2019 also no brake fluid is leaving the valve to go to the rear I'm confused. Were you able to bleed the right rear with one of the valves? If so, brake fluid has to have been coming out of that valve then. Do you still have that valve? If so, put it back on as it is good. Then we can troubleshoot why the driver's side wouldn't bleed. the old one valve. front brakes will bleed. the rear part of the valve. nothing is coming out of it. I loosened the line to see if any brake fluid is coming out. and it was dry. Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 30, 2019 Share Posted September 30, 2019 the old one valve. front brakes will bleed. the rear part of the valve. nothing is coming out of it. I loosened the line to see if any brake fluid is coming out. and it was dry. Yes, but you said that one valve you tried did allow you to bleed the right rear wheel. Do you still have that valve? Link to comment Share on other sites More sharing options...
snakebite8 Posted September 30, 2019 Author Share Posted September 30, 2019 Yes, but you said that one valve you tried did allow you to bleed the right rear wheel. Do you still have that valve? No. I returned that one. Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 30, 2019 Share Posted September 30, 2019 No. I returned that one. Then I suggest you contact Steve83 to see about buying his valve. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted October 1, 2019 Share Posted October 1, 2019 also no brake fluid is leaving the valve to go to the rear The combination valve is meant to shut off fluid flow if the internal shuttle shifts all the way over and sets a fault light. But they get sticky and don't return to center. Somewhere on FTE is a cross section drawing showing the seals (o-rings) and springs inside. Maybe you should try back bleeding, pumping fluid from the bleeder to the reservoir. I don't know if you can develop enough pressure to push the shuttle back by hand, but it's worth a try. I've done it before with my Silverline Mity-Vac bleeder hooked up for pressure instead of suction. Link to comment Share on other sites More sharing options...
Steve83 Posted October 1, 2019 Share Posted October 1, 2019 The combination valve is meant to shut off fluid flow if the internal shuttle shifts all the way over and sets a fault light.Mine never functioned that way - it allowed the leaking side to continue draining fluid until that part of the MC reservoir was empty. On a few occasions... I've never read anything that said it should stop flow under any circumstances when working correctly.But they get sticky and don't return to center.According to Haynes, and the way mine always worked, they never self-center. Once the leak is fixed, the OTHER side has to be bled (an intentional leak) to move the piston back that way, and stopped when it reaches center (light off)....a cross section drawing showing the seals (o-rings) and springs inside.Haynes has that, too. BTW I took this when I was disassembling that truck, just before swapping to the '93 frame & body: https://supermotors.net/getfile/931972/thumbnail/brakeadapt.jpg Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted October 1, 2019 Share Posted October 1, 2019 The combination valve is meant to shut off fluid flow if the internal shuttle shifts all the way over and sets a fault light.Mine never functioned that way - it allowed the leaking side to continue draining fluid until that part of the MC reservoir was empty. On a few occasions... I've never read anything that said it should stop flow under any circumstances when working correctly.But they get sticky and don't return to center.According to Haynes, and the way mine always worked, they never self-center. Once the leak is fixed, the OTHER side has to be bled (an intentional leak) to move the piston back that way, and stopped when it reaches center (light off)....a cross section drawing showing the seals (o-rings) and springs inside.Haynes has that, too. BTW I took this when I was disassembling that truck, just before swapping to the '93 frame & body: https://supermotors.net/getfile/931972/thumbnail/brakeadapt.jpg Well, by looking at that Haynes drawing *I think* you should be able to tell that if the spring centered shuttle shifts over far enough for the spring loaded switch's pin to drop into the shuttle groove (setting off the light) that the position of the O-rings preclude the flow of brake fluid to that side. At least that's what the Ford cutaway shows me. The switch plunger has to be pulled out (on 150's) or pushed in (certain years of 250-350) for the centering springs to reset the shuttle. Like brake fluid does if it's left to sit, the bores will get sludged up and coated. The shuttle will become sticky, and not travel fully over, to where it will set a light. But it also will not return to center if spring pressure can't overcome stiction. And if the 35 year old seals are shot they may not 100% keep fluid from weeping past. Edit: I think (your drawing should be the same) I'll gladly admit I'm wrong if you prove otherwise, and I'm not looking for any arguments. Show what you know. I'm man enough to accept that I cannot be perfect. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted October 1, 2019 Share Posted October 1, 2019 The switch plunger has to be pulled out (on 150's) or pushed in (certain years of 250-350) for the centering springs to reset the shuttle. This is why procedure should show that the plunger needs to be held out (or in) for any brake bleeding aside from while working on an already full system. Link to comment Share on other sites More sharing options...
Gary Lewis Posted October 1, 2019 Share Posted October 1, 2019 The switch plunger has to be pulled out (on 150's) or pushed in (certain years of 250-350) for the centering springs to reset the shuttle. This is why procedure should show that the plunger needs to be held out (or in) for any brake bleeding aside from while working on an already full system. Oddly enough, I found a post on FTE between two guys that were in my house 10 days ago. Start with Jim/ArdWrknTrk's post from 8 years ago and read down. You'll get to Scott/Kramttocs' post and then Chris/ctubutis' posts. Link to comment Share on other sites More sharing options...
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