[RickB]

If you have no knowledge of the repair process and he has no use for the tractor, I am not sure why you would even ask. A cylinder liner replacement can and should go along with several other steps and proceedures. Without knowing more about the condition of the engine or your expectations of its future performance, the question is impossible to answer as posed. In fact, that question is impossible to answer accurately until the engine has been at least partially disassembled and inspected. The range of costs spans several thousands of dollars depending on a multitude of variables.