Brother in General, they dint hide anything from you while selling... Normally for second hand car, you have to spend some amount initially for small work. Moreover you have to be very careful with the mechanic here. Most of them they don't know what is the actual problem. Once you give the car to them for checking they will remove all the parts and check, if they could not find whats the actual problem, they will ask you to change some good parts also just to claim their labor charges. Go to some good mechanic, find whats the actual problem, rectify it and drive happily and safely. Dont think about the car seller any more. Now its your own car.. Spend whatever the amount for your life & safe drive...