On mine, the strainer simply twists and lifts out. The mounting bracket cannot be removed. It is difficult to get all of the rust and corrosion out, expecially on the other side of the baffle. Try putting some steel balls or gravel in the tank and tumble it over, and over and over. Flush it out and do it again, over and over. I also was able to reach down in the opening and use brillo pads to scrub what I could get to that way. When the soapy water starts coming out clean, rinse with clean water. I dried my tank out by putting a hair dryer in the opening and letting it run while the tank was in the sun. Once dry, I rinsed it out with gasoline. I didn't coat mine.
You can also do a better job by taking it to a radiator shop and have them boil it out.
