same thing happened to me on my little mg zr.
turned out to be the connection wires under the front seats,my kids must have pulled the wires with thair feet .
chuffed to bits with my hippo,people forget the older the car ,the more it will fcuk up.
mine is 7 yrs old and its acting like a 7 yr old car.
lower ball joint needs replacing now witch aint a bad life span really.
its a lot cheaper than maintaining the wife.
this may help some of you with unexplainable water loss.
been loosing water for several days, eratic idling too .
finally traced it to the inlet manifold gasket .
replaced the gasket an hrs work,leak sorted:) .
hope it helps anyone else