Hey all. A couple hours of trying to blwed the brakes on my 78 f150, I am at my point where I must give up for a few and ask for wisdom. I started with removing the master cylinder. Fluid in it looked like caramel. Cleaned it out. Reinstalled . Bled back right till just a few little bubbles where coming out. Bled the rest till no bubbles and went back to the right aft. Big bubbles came out. Sounded like a soda fountain out of soda. Kept at it for a while till back to little bubbles. Checked all the other brakes with no bubbles. Back to right aft and more air. I have rUn about a quart and a half through that one brake and it still spits air. I am using the 2 person system and my daughter stopped thinking this was fun about a half hour ago. Any ideas?

 

Have you thoroughly inspected the back half of the system from the proportioning valve back...rear hose, junction block, hard lines and cylinders for leaks?

How's the bleeder valve on the right rear?

It sounds like you have a leak somewhere along the line that's sucking air into the system. If you're saying that it's only happening at the right rear, I'd start in that area.

 

When you took off the M/C to clean it, did you bench bleed it before re-installing? Could be a problem with air....and all the fittings/connections are good and tight?

blackjack33 is onto something....obviously there's air getting in the R rear line....maybe others, too, but not as noticeable due to the length of the RR line.

 

So when I fit's tried to bleed that one the bleed bolt was completely blocked. Soaked it in alcohol for a bit then blew a bunch of garbage out with shop air. I did not bench bleed it the first time. Did it earlier today though with sa me result. Another fun addition to the day after bench bleeding the bleeding the system , still getting air in right rear I tried to turn truck around and the brakes did about nothing . Wondering if the master cylinder did better with all that junk in it. Guessing I blew the seals internally . Will check for a leak while waiting for my new master cylinder to arrive. Thanks for the help guys.

 

To add. The clog was in the same right rear the air is getting into. Wouldn't there be a leak of fluid if there was a hole in the pressure system? Just curious .

 

Thanks. Yet another thread that solves a problem!