I replaced the bad master cylinder and I was able to build the smallest amount of pressure in the brakes. But I looked at the bottom of the truck and found a leak in the rear brake line. Im broke so I tried to jb weld it lol. And now I have just the smallest drop of brake fluid coming out of it. Would that small of a leak cause my brake pedal to go completely to the floor and have no brakes at all. If so can I just block off the rear brake line from the master cylinder until I can get the whole brake line kit. And if so what size bolt do I use to plug the master cylinder?
When you replaced the master cylinder, did you do a bench bleed?
Did you bleed the system at all four corners?
Why did you replace the master cylinder in the first place?
If you have a leak, you will get air into the system at that point. JB Weld won’t hold the pressures your brake lines are.
Some people have been able to block off the rear, but it’s definitely not advised. It would not be a bolt, it would be a plug. Take your old master cylinder to the hardware store or automotive store and find one that fits properly.
I get that you’re strapped for cash, but having a compromised brake system is setting yourself up for bigger issues in the event you can stop in the event of an emergency and wreck your vehicle or worse, hurt someone.