I had a shop replaced the master and booster on a 1999 dodge ram 1500 because the fluid leaked into the booster. Now about every 5 days air gets into the rear brackes and I have to bleed them and its fine for another week. I don't find any leaks and no fluid loss at the master so I had the shop replace the master again but I'm still having the same problem with air entering line and air is always found in the rear brakes. Any body have this same problem???

 

was the MC bench bled ?

 

Check the distributing valve on the rear and also the black rubber lines to each wheel could be bad.


Also, if they didn't open the ABS system by connecting to the module and bleeding it you can get this issue.

 

is it possible they didnt tighten one of the bleeders enough?

 

Check the main line that feeds both rear brakes, could have a pinhole leak.
It runs over the fuel tank and usually will break about a foot back from where it transitions to the rubber line. it's hard to see but I would say 1 in 5 owners here have had this leak or worse, rupture.....Myself included