rattleing engine

Our van engine started rattling (metal on metal) on the last trip out just before we got home it's not clutch or top end although the noise is at the top, I think it's big end so does anyone know if the sump can be removed insitu It looks like it does and I started to take it off today but its to cold and getting dark then if that's the case anyone know if the con rods and pistons pass the crank?

Right rattle seems to be the back cylinder but the problem has been traced to the cam belt tensioner the bearing has failed which would tie in with the odd squealing noise which has happened a couple of times for a second or two then gone again which now I have a failed bearing I realise that thats what the noise was, just hopeing that the valves have survived don't really want to take the head off for the fourth time

at least you know how to do it and should be quick as how many times you've had it off..

just driven it up the road and back sounds a little tappy but it was anyway pulled good up to 40mph (indicated) up hill and back again so when I get paid tommorrow I'll go and stick some fuel in for a longer test.