My turbo has started making a loud whining siren type noise on startup. 

 

It only lasts for a about 1-2 minutes then it goes back to normal. I also have low/no boost during this time then its all 100% fine after.

 

Any ideas on the cause? Dont think the turbo is knackered as its only on 40k standard turbo and the fact that within 1-2 its fine again. Done an oil change which changed nothing. 

 

Thanks

 

 

It sounds like the vacuum system may not be operating the turbo actuator until it's been running awhile, start by checking the vacuum system for leaks.