Random overheating

About a year ago my '99 Subaru Forester (180,000 miles on it) began overheating when the outside temps drop below 55 degrees. We replaced the thermostat (twice), had the cooling system and radiator checked out, the water pump is good and we aren’t losing coolant. Once the temps got above 55 last spring the car has run normally, even getting better gas mileage than usual.

This seems to have everyone stumped. I’ve read about the head gasket issues with Subarus but no one we’ve talked to so far seems to think that is our problem. Any ideas, anyone?

Maybe the problem is air, not coolant. Maybe your electric fan is not switching on when temps fall below 55. This might be caused by poor thermal contact between the fan temp sensor and the radiator.

thanks, we are learning a lot by reading the threads on overheating and hoping it is something like a bad sensor or a poor contact, as you suggest. That would be a whole lot better than having head gaskets replaced!

If you had a bad headgasket you’d be overheating above 55 degrees.

I like the suggestion you’ve already received.