OK has anyone changed them on a 2.4 210bhp? At the moment I'm going through a problem solving mission of a knock/tap sound. So far I've done dmf/clutch/bearing, deswirled and cleaned manifold, 5 new injectors, glow plugs, engine flush and new oil. Next on the list is tappets and followers. If you changed yours, did you change the whole lot? Can you tell which ones are faulty? Is a big job?