It sounds to me like you're doing it right, if you're winning money from him.

Bet back at him a couple times and see if he runs. I'll occasionally use a "timid maniac" style on a passive table, and just beat up on anyone who doesn't hit back. Like most bullies, a maniac only picks on the kids who don't fight back.

If he doesn't run, wait until you have something (TPTK is enough), and call him down. Maniacs will throw all their chips in with nothing, and then you can take them away. If he hasn't thrown them all-in by the river, go all-in yourself and see what he does. If you get him to fold on the river, he won't be bluffing you again for a while.