Car makes a honking/moaning noise while running. Noise is stopped by disconnecting and blocking PCV pipe where it plugs into the cam cover at the front of the engine.

I am guessing that there is some sort of reed valve type mechanism that is not working properly but it looks an absolute bear to get at.

Anybody done one of these before? What bits am I likely to need and how long should I allow?

Normally I would want to dissassemble and assess before ordering up replacement parts but customer really wants job done all in one day if possible.