Hi guys and girls

I have a 155bhp A6 2.5 tdi thats just had a new turbo at 180,000 due to vane failure new put on along with new tank pump and new injector pump, car then taken on holiday to europe 4000 mile trip burning oil out the back like no ones business used 7.5 litres over duration of trip, turbo removed and sent back for rebuild, found nothing wrong problems traced to crankcase pressure forcing oil out turbo shaft. I have just stripped turbo off removed breather filter in bowl in Vee and all seems fine, no dirt at all, there is a small hole in the bottom of the breather into the sump which has a small sprung plate that seems to seal off the crank case from breathing and only opens when pressure pushes it down from above, so how does it breathe and has anyone come across this problem?

i identified problem by running the car for a few hundred miles with a foam filter in place of oil filler cap and have had no smoke and used virtually no oil other than breathed out the filter

cheers Doug