If your brakeline has rust on it its probably got a small hole in it... Or alot of the times you can get rebuilt wheel cylinders.. so make sure its not bad..
Have someone pump up the brakes while you have the wheel off.. and see if its coming from the back of the backing plate, or take the drum off and see if its coming from the wheel cylinder..
But like others said, you always want to replace them in pairs... Because when you do one, the other side always goes..
And for the guy that asked me a question, If i cant get the drum off after deadjusting it, and hammering on the drum.. I quote ebrake cables, shoes, drums, springs, wheel cylinders, everything thats in there... adjuster wheels, etc..
Then if they want to spend the money I will spend the time getting the drums off.. otherwise its not worth my time..
2006 Jeep SRT-8 Grand Cherokee
K&N Intake, Magnaflow Exhaust, Eibach Lowering Kit, Custom Tunes, FRI Lilboy Cam 114 LSA