Gt tdi my golf gt tdi 130 is blowing black smoke, no power, can hear the turbo but not kicking in, feels as though the whole air is coming out of it when accelerating, happend all of a sudden. im not sure if the turbo is blown, how caqn i confirm

TDI I take is turbo direct injection so if that is the case you have a turbo problem or a split intercooler
what ever , the air/ fuel ratio has altered to excessive fuel
the noise could be a blown intercooler hose , split intercooler or turbine wheel in the turbo breaking off
Take it in for a proper diagnosis and have the codes read

Is this all the time or mostly on kick-down?
if there is always thick black smoke it suggests a build up of burnt coke in the system. Unlikely to be air intake related as it is from spent/burnt fuel. A good service of the plugs and filters should resolve this

blown head gasket

Black smoke from the tail pipe means the engine is not getting any air like a dirty air filter. I think your mechanic is telling you is that you need a new turbo. The turbo boost incoming air pressure to the engine and if it is bad then it will not let enough air into the engine causing black smoke from the tail pipe.

check the turbo hoses, they are renound for dry cracking, very hard to see at first glance

changing the mass air flow meter will solve this problem.

sounds awfull like a dud airflow meter vw's are prown for them if there is no power u would think there was no turbo it would be defo a airflow meter

lods have a problem it a skoda 19tdi no power when i give it the boot 80 km only turbo kicking in ok changed air flow , washed out boost valve, would u think the timing is out

It's probably the turbo you're hearing. They spin very fast and make a noise like that. Ever hear an 18-wheeler go by you and accelerate and they make that high-pitched whistle? That's the turbo spooling up. Now, if it sounds like a dentist's drill, that's usually a sign that the turbo is failing, but I'd bet that since your car is under four years old, as long as you've kept up on the maintenance, it's the normal turbo spool.