If it's alright, I'd like to add to Hannelore's side of thinking...
People like this don't usually fall, not totally. They seem to be able to find others that will "keep them standing"... I say this because I have a brother in his late fifties that could bare the initials LW. He goes from party to party - family, friends, friends of friends, friends of family - it makes me sick. When my mom finally kicked him out of her home four years ago, he made the circuit. Now he's virtually back at my mom's home. These types of indiviuals have a certain mentality. In my opinion, he needs a mentor, possibly someone outside the family. Letting him fall may not be the answer. Keeping tabs on him might be, and that may include certain contributions to his welfare. Give him $25-$100 for the truck in your yard... don't give him cash. Instead, go pay one of his bills with the money, then sell the truck for more than you gave him from it.... you should be able to get that much for the motor alone (that is if by skimming the post I got the full understanding of what you've shared).