Do you know if the person that sold the car to you is a trader, On the side, or was he a genuine private seller? Had they had the car very long, is there anything that you might thing they new the engine was on its way out, you say he has got another engine?, if you don't get anything back from them you should seek professional advice, only problem is if private sell it is hard to get anything back but not impossible all the time. When you buy a used car from a private seller, you don't have the same rights as you do when buying from a dealer. You have no legal right to expect that the car is of satisfactory quality or fit for its purpose, but there is a requirement that it should be 'as described'.