I understand that. However the over heating occurred both with a 50/50 mix and with pure water. And the engine ran just fine on a 50/50 mix prior to the initial overheating event.
Subsequent to the second overheating event, it has had nothing but water in it since I didn't want to waste coolant. And it continued the same overheating behavior. So I don't think that the viscosity of the coolant mixture was the cause of the overheating problem.
