There is a filter for the turbo in the front crank shaft main bearing journal.
6c683 on the diagram and part number 1316019
http://www.catcar.info/ford/?lang=en&l= ... EzMw%3D%3Dhttps://www.ebay.co.uk/itm/393457831700?
This has been suspected (meaning no one really knows) as the cause of many turbo failures, it is plastic and falls to bits over time or becomes clogged with neglected oil changes.
Engine has to come out to change it ... as crank has to come out, ...... if it is that ?
could also be the turbo has reached the end of its life, which could be anything from 100,000 miles to 180,000 miles on normal oil changes or more if oil changed at 6000 mile intervals
all the best.mark