So when im driving and im in a high gear at low speeed like say 25 in third at low rpm i hear a knock noise. but when i rev the engine in neutral or get to higher rpm it dosent knock . What is causing this and why at low rpm on higher gear?

 

are you sure its a knock and not a valve tap?

 

i have a similar problem but everytime the tach reads 3k i hear a slight knock, i spun a rod bearing a while back completely rebuilt the engine and its knocking, idk what it is

 

i dont think so but its posible my valves are chattin alot latley but at low rpm i hear a metal knock noise but when it gets passed 3k it dosent do it at all