Black smoke from dipstick tube

[Liverpool1967]

Hi, can anyone help with this one? My Leon fr 184 tdi has quite a bad amount of black smoke coming from dipstick tube when the engine is at full temperature. There is no hint whatsoever of any smoke from exhaust under acceleration! I have had a diagnosis of piston rings and been advised to have this sorted. Sounds a bit extreme to me. Can anyone shed some light on this?

 

[Butty]

I'd go for rings as well then worn valve guides. How often is the DPF cycle?
Was a leakdown test performed to help confirm the diagnosis?

 

[Liverpool1967]

Hi, thanks for reply, dpf seems to cycle quite often, not sure if leakdown test has been done or what that is?