jdupa

Can anybody help and diagnose this sound? Dealer says it’s normal but I’ve not heard that before. My 06 E350 engine (45K) makes this knocking sound, seemingly coming from the passenger side of the engine and present when the engine warms up. It is heard in the background (distinct knocking) of an idling engine in this mp3 recording: engine knocking sound

mcleantmw

Mine is a V8 and it's also a little noisy when first warming up and then goes away and especially noticeable during the winter months......I've had my MB Dealer check it and they also say it's normal. It appears that some of these vehicles are a little noisier than others but I've been told by even independent repair shops that these engines are bullet proof.......it's just the other elements of the vehicles' design that may fail.

vettdvr

Valve tappet. Unfortunately a normal sound

jdupa

I agree, the foreground, faint, light metallic noise is valve tapping, all 24 of them. BUT then, there is a deeper, single, less frequent background knocking sound, I am sure you can hear it towards the end of this recording.