The Ellis Island website is listing 2 MANCIUs that passed thru that port.Worth to check them out just to see where they were going in US.
You do need to locate a name of a town that he came from in order to research further.
The Romanian phone site is at http://www.whitepages.rohttp://www.whitepages.roand the name Manciu lists in the city of Timisoara, Bucuresti, Resita and possibly few more places but I did not look any further.
If anyone had social security numbers, was naturalized citizen than those forms can be requested and there should be usefull information on them.
Check out if LDS-Mormons FHCLibrary is listing any church films but you do need to know the name of a village.