Nissan Primera P12 dci sudden turbo drop out / in

petterg wrote: If the turbine blades on the fresh air side of the old turbo were damaged, you may damage the engine if driving before everything is cleaned up, as there will be fragments of metal where it's supposed to be air only. When turbo is broken and leaking oil, the air flow will be low and if you're lucky (I think I was) they will collect in the intercooler. Once you get a new turbo the air flow will increase, which will make whatever is collected in the intercooler blow into the engine and damage injectors, cylinder heads and more.

Yes, that is what can often happen when the old Turbos fail and break up, the deposits are spread all around the engine and sometimes people fit new Turbos expecting to solve the problem BUT you have to clear all the remains/ deposits from the failed Turbo which are still in the engine. Oil feed pipes/ oilways/ filters/intercooler/sump/ sump strainer etc will all need to be cleaned out/ replaced. Specialist Turbo Fitters should know this and follow strict procedures but sometimes the procedure is not followed and many of the deposits remain without being cleared and the Turbos fail again- sometimes lasting just weeks or days even after being fitted as new!
Its not just a case of Turbo failing and putting a 'new one' on. Best to catch them before they fail(regular inspection for signs of excessive play or blades distorting)- than trying to sort the mess out afterwards for sure.