MHM-have you no sympathy???:behindsofa:
What engine is it?-The state of the header tank points in that direction but I would pull the spark plugs out one by one and see if one of them looks like it's been in a washing machine, that will identify the dodgy cylinder. Is there any water in the sump, if needs be, remove the sump plug briefly and see if any water runs out-do this after the engine has been standing for some time.