Hi!I have a ROver 414i. I recently changed the engine (same size,model and make). After a few days a noise started...like banging underneath the car...whenever you are on gear!It gets quiter when you are off the gear! You cant hear it at high revs...but at low revs its easy to hear..and it follows the enigne revs....you know..it goes slower as you slow down!!Any idea?

thank you!
Fuermen