A couple of weeks back I put about 110 miles on my BN7 to attend a Healey club event here in north Florida, having the pleasure of driving home in the dark with the top down for the first time. Very refreshing. The following morning I happened to check my coolant expansion jug (truthfully, a large plastic ketchup bottle) and found it dry as a bone. The radiator coolant level was normal. The expansion jug was not leaking. The car never ran over 190 degrees during the drive, and the engine with a 160-degree thermostat gave no indication of being hot when I pulled into the garage. The oil level was normal. The car has a new water pump that isn't leaking and a rebuilt radiator. There was no visible coolant leakage on the floor. Neither coolant valve, the one on the radiator and the one under the manifolds, was leaking. Just for the record, I've since changed both the coolant and the ketchup bottle. So, where did the coolant go?