I have an ef 4 litre engine. the engine ran well except that the head gasket needed replacing. I replaced the head gasket, timing chain damper and giuides, but when I put it back together there is now a knocking noise and I dont think its in the tappets. I had the timing case off for inspection, but again its still knocking. As i said it ran ok before. I dont think the rods are bent on behalf of the water consumption. Any ideas