89 engine problem

I recently baught a1989 integra and the thing started acting strange 50 miles up the road. there were some small pufs of white smoke coming out of the back. after i pulled over and checked it out the car wouldn't start again. i took it back to where i got it and they said it was just a cracked waterline. can this be true? i dont know alot about cars but it seemed worse than just a cracked water line.if it is not a cracked water line what is it?