My Rover 25 started overheating a couple of days ago. It has had the head gasket replaced already some years ago, and I suspect this might be the beginning of another faiuler, so I'm going to take it to the shop next week. What I would like to know is, can I put water in the expansion tank as a preventive measure for the next couple of days ?
You can use water, but I'd highly suggest you get some 50/50 to tide you over. That also depends on how much coolant it's losing. If it's a small amount, distilled water would work just fine as long as the temperatures are not getting too low (sub 0°F). Either way, you'd want to make sure you pay attention to the amount in the surge tank and keep it up to where it's supposed to be.