Traded my truck for a car that broke down?

I went to a car lot that I have done business with since 2005. I traded my 2000 Ford F150 for a 2001 Ford Explorer. Two weeks after a traded, my car broke down. I called the man I always work with and he came and got my car to fix it. I have been unable to pay for the part as of yet. Can he keep my car?

If you don't pay in 90 days, Yes. (if you signed a service agreement) Known as a Mechanics Lien.