98 CLK 320 problems
 

My 98 W208 seems to be having issues as of late. When I start the car, you can hear the engine knock three or four times. This only occurs when I start the car in the morning or when i restart it after it has been shut off for at least 20 mins. I'm suspecting the valve lifters but am not sure. There is also a faint ticking sound coming from the engine compartment as well.
Since the 98 was the first year of production for the motor and the CLK, does anyone know of any related service bulletins/updates I need to be aware of? Thanks in advance. . .

ttt