Hey guys, I know this topic has been beat to death but i have a question. My 2006 ctd 2500 4x4 just recently started making groaning noises when im at idle trying to park the wheels are extremly hard to turn at a certain point (close to full lock) . Now i know i probably have some parts i need to fix but i just want to know what causes that mainly.. bad pump? or bad steering box?

I know im going to have to flush the system and i have a lift at home to do so but i just dont want to be replacing things that may not need to be. lol the ole saying goes if its not broken dont fix it! well ya.. thanks for any help!