I have a 2006 f-350 with 6.0. it has 152000 miles . at 120000 miles I did the head studs. egr replaced. new oil cooler. and several other things. the truck currently is making a high pitch noise. seems to be turbo . today I saw a puff of white smoke. and it was running a little warm . water was low. truck has great power when you step into it and puts out a little black smoke when doing so. my question. do I have a bad turbo ? do I have head problems or possibly something else? please help thanks. anyone?