It is the wheel bearing, these are notorious for problems. You can get a descent replacement bearing for about 100 bucks, but be watchful of the quality. The ones that are made in north america seem to last a lot longer. I have replaced these on a few of these vans and the ones I replace that come from the local auto parts stores that were made in china seem to last about 1 yr. vs the AC Delco one that is made in the US I have not had to replace again, yet (being the key term here)