Car came onto our forecourt with complaint of noisy and not running right. A quick listen indicated a misfire and code read agrees but also with cooling issues and low fuel.

Not a major problem at the moment but my concern is on start up and switch off a knocking can be heard at first from iside the car i thought it was a DMF failure but under the bonnet the noise is all from the top end at the front of the cam covers nothing heard underside so prob not crank pulley.

My question is not knowing this engine is this likely to be how it is (wouldn't think so as it's so loud) or how sinister is it likely to be.
Any help would be appreciated
Thanks in advance
Kelly