Hello I have new Holland 215 Exacavator and when I start the engine after 5 second I have an abnormal pressure on the excavator the return hose from the main hidraulic pump gets a really loud shock after that it’s like an hidraulic function it’s activated and from the engine exhaust comes black smoke We are new in the domain of construction equipment and we don’t really know everything about those machines we work mainly on agriculture equipment
Sounds like the return hose maybe clogged or collapsing and Diesel's lugging under the load til idles back up