Sold a car now being sued

I sold a 91 plymouth laser RS turbo with 126,000 miles on it. I few days later the car started to smoke and she brought it to a shop. They said the turbo is leaking oil and will smoke a little but it is ok. She says the turbo is blown. I was a fool and never filled out a bill of sale saying AS IS. She says I was aware of the problem, but it was fine when I had the car and when she drove it home. What are my chances of winning this, and what do I need to do.