Yeah, confident there's no water got in the inlets, I covered them with cling film when i raised the manifold specifically for that and to stop any debris getting in.
There's no antifreeze in this water and it's quite a small amount.Engine hasn't been run in 2 or 3 months so I'm thinking it's just rain water got in somehow.
All the hoses check ok, think I'll change the thermostat while I'm at ... stupidest place I ever saw to put it! Is there a gasket on the thermostat housing? I can't see one in the manual I downloaded...