I bought A Prius 2010 Gen 3 with 200k Km 2 months ago and it started to knock couple of weeks. I did an oil change, I cleaned the intake with the EGR System, I changed the spark plug and the sound is still there. It's only knocking when the engine is hot and few seconds when I start the engine. I don't have any check engine or any lights on in the dash board. Im not loosing any coolant. I have a video for the sound but I can't post it since Im new here.
are those engines known to have problem with the hydraulic lifter? For me, it sounded like a lifter problem.