2.0 Diesel RF7J 143 bhp knocking sound from engine, main bearing or flywheel?
 

Hi guys,
Bought a Mazda 3 2.0 diesel 143 bhp RF7J Sport 2008 with 40k miles on the clock. The car has got few issues.

1. Lights flashing on dashboard. Engine (orange), traction control, flashing DPF and automatic lights positioning.

2. Knocking sound from engine and vibrations on low RPM (up to 2000). Gets louder when clutch is engaged. Over 2000 all fine. Sounds like main bearing or dual mass flywheel. Drained the oil, no sign of pieces of metal. Oil filter clear, drain screw fine. Took down oil pan, clear as well. Wanted to get do main crank shaft and bearings but got to some kind of cover and couldnt take it off (picture). Do you have to remove gearbox to take it off? Got my fingers on bearings but everything seems very tight. Oil pump net strainer (??) inside oil pan clean. Youtobe video with knocking sound here: . Any ideas?

Did you work out how to do this ive just got to the same point! Are there any dowels or is it just the sealant stopping it coming off?

Theres two more bolts behind the flywheel some like mine do not have an access hole!