Obnoxious whining noise cm 871 front engine

[Big red 09]

Thanks for all the replies that does help Long story short I have decided to buy this truck from my employer after it was rebuilt and majority of miles were put on by me and this whining noise has gotten way louder and yes it is loud at idle over the engine itself When we dropped it off for inframe he went to talk to service writer and I should have went in with him to make sure this issue was addressed I have not been part of an inframe build before so I’m not sure as to what should be replaced other than pistons rings bearings etc I was an auto mechanic for many years so have good knowledge of engines in general and through searching for the real answers here I could kick myself In my opinion too NO engine should have these kind of gear train noises and the thought of catastrophic failure has crossed my mind also
It looks like I will have to call rebuilder and asap and get the work done the right way and of course down time right now is not good since we are in very busy season
I also struggle to find competent places to get work done these days and although I have done the majority of repairs to this truck I’m still learning these ISX engines and like them but want quiet motor that runs properly
Truck is 2009 KW T660