Rod knock or Main bearing knock?

[yaris2010RS]

it would thump when u innitiially change the load on the enigine (such as changing from park to drive) but it will not continue to thump and would whine and thump as the engine accelerates. at higher rpms u would also notice the engine would feel unstable.

with how u are describing it i highly doubt its something that serious.

block the wheels and put the car in drive with the e-brake up and look at the engine. try to see where the sound is coming from. hold things u may think will be hitting the engine or body. does it sound like a metal on metal sound or just hard force on a hard surface? feel the top of the engine while running and see if u can feel the knocking syncronized with ur ears