Iceman_

Greetings, I recently bought a CL 500 with engine M273, and didnt notice at first it has noise coming from engine. It's a metallic noise, about two times slower than the revs of the car, it goes faster with the revs and it completely disappears above 2k rpm. It's only pronounced in the low rev range, mostly at 1000 rpm. Car has 180 000 km on the clock with service history from MB, now has 5w30 MB oil. This noise reflects on a wall when you pass coming to a stop. I'm wondering about hydraulic lifters or rod bearings.. I've listened a lot with stethoscope and it's more towards back of the engine at the exhaust manifold right before exhaust starts. Any help will be much appreciated!