Vauxhall Vectra C life 1.8 16v - knocking on start up - MrEdd65

Can someone help me when i start my car it has slight rattle ,then it stops the car seems to run ok but i need to fix it as i am hoping to sell , there is a post on here about a vectra vvt with simailar problem and they mentioned valve timing gears and selenoids , but am not sure wether my engine is the same my engine is Z18XER any help would be appreciated Many Thanks