My 05 CL500 is nice and quite - sounds smooth and as you would expect - when I rev the engine in neutral. However when I select drive and accelerate away it sounds as if there is a valve type (tappety) noise coming from the engine which makes me imagine poor valve clearences. But as said teh engin eis smooth and quite when revved in neutral.
Is the noise coming from something else other than the engine headers??
It does it to a lesser extent in reverse - but then I dont accelerate or rev the car under load in reverse
Your advice and help would be invaluable to discuss further .