interesting discussion of wastegates:
http://www.bankspower.com/Tech_howturbowastegateworks.cfm
My 87' 300DT wastegate as partially held open due to carbon build up over the 250K miles it was in service. Cleaning out the hard, almost solidly baked-on crud returned performance to normal, allowing it to spool up quickly (before that it would slowly gather acceleration, as if it was a 240D
Diesel turbo engines live by the action of their turbos, if any little thing goes wrong with them performance suffers in a big way
