I have been experiencing a clicking noise in the driver rear brakes which only happens when I am using the brakes. I took off the rear wheels and the wheel cylinder on driver side had a lot of gunk on it so I cleaned off the gunk and put the tires back on. clicking noise went away for a day and then came back and now sounds more like a dragging sound. Is the wheel cylinder bad or is there possibly and issue with the drums/shoes? Last replaced the shoes and had drums turned about 30k ago...

 

take the drum off and peel the boot back on the wheel cylinder. If there is any fluid inside, the cylinder is leaking. When brake fluid gets on the shoes, it causes them to stick and bind on the drum surface. If the wheel cylinder is leaking, I would recommend replacing the shoes also.