Engine sounds like tractor

[rogerdygas]

My a20nht engine sounds like a tractor especially when cold, this does not go away when revved.

I have plugged it in and the cam oil valve is faulty which I'm replacing, could this cause the noise?

Or is it the dreaded timing chain or balance chain? If so should I also replace the vvt cogs?

[kentishbloke]

Not sure it'll help but my 1.8 petrol sounded like a tractor a couple of years ago, replaced both cam solenoids (removed filters from new ones before fitting) and the sound went away, but get a short knocking sound once in a while when I start it after it's stood for a few days.