rfcr Posted July 8, 2014 Report Posted July 8, 2014 Hello All, I have a problem that I can not figure out. My master cylinder does not seem to be working, I plug it in and it just sits there??? LOL Okay now the real problem, I replaced all the internal parts in my 1946 Plymouth P-15 Deluxe master cylinder and all the brake lines, wheel cylinders (front and rear) and new shoes in the back. After connecting everything and pumping for about 30 minutes I cannot get any air, pressure or fluid out of the rear right side bleeder. I disconnected the lines at the M/C and pumped the pedal thinking I might get something out of the M/C and NOTHING. I am at a loss and very frustrated. Any help out there? I tried uploading a picture of my M/C components but I can't figure that out either!!! Quote
Don Coatney Posted July 8, 2014 Report Posted July 8, 2014 Need more information. Can you describe the procedure step by step that you used to bleed your brakes? Quote
Conroe Powdercoating Posted July 8, 2014 Report Posted July 8, 2014 ^^ what he said and also, did you bench bleed the master? Quote
rfcr Posted July 8, 2014 Author Report Posted July 8, 2014 Sure can. After connecting all the lines at both ends, all drums are in place, I filled the M/C with brake fluid and had my wife pump the brakes. 10 pumps and hold, open the bleeder and close pump 10 more and on and on for about 30 minutes and nothing. Quote
rfcr Posted July 8, 2014 Author Report Posted July 8, 2014 Conroe Powdercoating, Explain bench test procedure. I did assemble on the bench filled with fluid and hand pumped to see if anything comes out where the 2 lines connect, nothing. Quote
Conroe Powdercoating Posted July 8, 2014 Report Posted July 8, 2014 I am reading into the story that you rebuilt the old master cylinder? IMO, that probably the issue, did you hone the cylinder or even check that it wasnt egg shaped? Can you for sure say its rebuilt/re-assembled correctly? Your obviously getting nada from the MC, I always bench bleed them but honestly think you should be getting something as far as pressure even though you didnt do that. I would guess based on the limited data that the MC is toast or incorrectly rebuilt. Quote
Don Coatney Posted July 8, 2014 Report Posted July 8, 2014 You might want to try this http://www.youtube.com/watch?v=Mdcn1USVQ-w Quote
Conroe Powdercoating Posted July 8, 2014 Report Posted July 8, 2014 Conroe Powdercoating, Explain bench test procedure. I did assemble on the bench filled with fluid and hand pumped to see if anything comes out where the 2 lines connect, nothing. mount the MC in a vice, connect short lines that run from the side into the fluid bowl and bleed the master via pumping the rod and purging the air from the valving, then install. If you dont have pressure on the bench, she wont pump pressure in the car either. Quote
desoto1939 Posted July 8, 2014 Report Posted July 8, 2014 Since you are not getting any fluid out of the MC I think you might have rebuilt it incorrectly. Take it apart an look at the relief post you might have this is backwards. rebuild it again and then see if you are getting fluid. Also check that the two holes in the MC are open in the body where the fluid goes. Also check the small hole in the cap make sure this is open. Get back to us on your findings. Rich HArtung Desoto1939@aol.com Quote
Don Coatney Posted July 8, 2014 Report Posted July 8, 2014 To bench bleed the master you should make a loop so the lines return to the master as pictured. This is a dual chamber master but the same applies to a single chamber master. 1 Quote
rfcr Posted July 8, 2014 Author Report Posted July 8, 2014 I used my service manual when installing the parts so I'm pretty sure I got it right. I did notice that the manual shows a "port" and a relief port. I can not locate the smaller hole. Quote
rfcr Posted July 8, 2014 Author Report Posted July 8, 2014 Don Coatney, I am using the same manual. One question is the cup just in front of the piston, when I received the rebuild parts the piston has a rubber cup mounted on the front end (closest to the plunger) not in front of the piston. I'm thinking it's toast. What I don't get is that when I bought the car the brakes worked going around 10 or 15 mph. Quote
Don Coatney Posted July 8, 2014 Report Posted July 8, 2014 Brakes should work at no speed and all speeds. I don't understand why speed has anything to do with when the brakes work. Ports are pictured below. Quote
rfcr Posted July 8, 2014 Author Report Posted July 8, 2014 I understand speed has nothing to do with it, just wanted to say they worked before and now after replacing the internal components they do not. The question is, should the cup be on or in front of the piston, I think it should be on not in front. The pictures you sent are the exact to what I have down to the small relief port. I don't understand this so I guess I need a replacement. Quote
Niel Hoback Posted July 8, 2014 Report Posted July 8, 2014 Bench bleeding a single pot MC is not necessary. There is no procedure for it in the shop manuals, because it is not needed. If you just want to see if the piston will develop pressure by plugging the two outlet ports, that will work, but you needn't do it before you bleed the entire system. Quote
rfcr Posted July 8, 2014 Author Report Posted July 8, 2014 Niel Hoback, I did assemble the MC on the bench and plugged the 2 holes with my fingers and pushed the plunger, I felt a little pressure but not as much as I would expect. This might be nothing but the illustration in the book shows the piston with a rubber cup in front, I think it should be on the piston. Am I correct or not??? Quote
Eneto-55 Posted July 8, 2014 Report Posted July 8, 2014 That photo is showing an expanded view, so it may not show all of the parts as they would appear when assembled. I'd open it back up, and look it over logically, asking myself "How does this work?", then once you understand how the fluid is pressurized & how it returns after each power stroke, you should be able to see how it is supposed to go together. Quote
Conroe Powdercoating Posted July 8, 2014 Report Posted July 8, 2014 I have one on the shelf, I'll pull the piston tomorrow and photograph it for ya if you want. Quote
Dave72dt Posted July 8, 2014 Report Posted July 8, 2014 The kit should have had 2 cups, one that goes on the piston, by the plunger and the other that goes on the other end of it. That one should have some little notches on it and a thin washer , either glued onto the rubber, or separate and that edge goes against the piston. Cups in backwards or missing, will not work. Cup side is the fluid side. It uses the fluid to help push the edges out to seal them against the cylinder. Check valve at the end usually locks into one end of the spring. Quote
linus6948 Posted July 8, 2014 Report Posted July 8, 2014 Don just how small is that port and what is tool or device is recommended to clear it out, and if it is clogged what symptoms will the master cylinder display? Quote
Solution rfcr Posted July 9, 2014 Author Solution Report Posted July 9, 2014 Conroe Powdercoating, Thanks but don't bother with the photo. Thanks to all that replied. After I get the brakes working I'll be installing the gas tank and fuel up to the fuel pump. This SHOULD be uneventful??????? Quote
rfcr Posted July 9, 2014 Author Report Posted July 9, 2014 linus6948, I'd like to see the question to your question. Quote
Don Coatney Posted July 9, 2014 Report Posted July 9, 2014 Don just how small is that port and what is tool or device is recommended to clear it out, and if it is clogged what symptoms will the master cylinder display? It is about the size of a big sewing needle. If plugged the brake fluid cannot bleed back into the master cylinder and the pedal and brake shoes or pads will lock up. 1 Quote
Dave72dt Posted July 9, 2014 Report Posted July 9, 2014 What was the cause of the master cyl not pumping fluid? Sounds as if you got it working. Quote
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