Are hydraulic lifters, cam shafts, push rods, and valves consider to be "internally lubricated" parts of the engine? The reason I am asking is that I've noticed that my '99 E320 (with 91K miles) has a slight tap when idling. I assume that this is due to one of the items I mentioned above (lifters or camshaft being my first guess) and I still have the car covered under a Starmark warranty that states that "internally lubricated" engine parts are covered. So before I take the car into the dealership I wanted to verify my belief that these are indeed internally lubricated.
Josh