Can anyone tell me exactly what engine this is?

[itchyfeet]

Most of these cooling ststems leak so take some coolant with you.
Your low level coolant sensor obviously isn't working so check that inside tank regularly, a pain to get to when loaded I know but the top up tank behind flap is no guarantee of a full inside tank.
If there is a coolant leak it can just draw air in on cool down rather than drawing in extra coolant from the top up tank.

Kev, from that tiny pic pipes look standard to me except oil breather is vented to the side, (possibly because of poor emmissions) and the extra pipes at the back look like the lpg cut in.

[kevtherev]

Kev, from that tiny pic pipes look standard to me except oil breather is vented to the side, (possibly because of poor emmissions) and the extra pipes at the back look like the lpg cut in.

So that's an evap on the left?

[itchyfeet]

Mmm dunno well spotted