I recently bought a 2006 forester which overheated before I got it home ( 60 miles ). The dealer took it back for diagnosis and repair. They changed the thermostat and the filler cap but the problem remained. They then changed the water pump and used a thermal imaging camera on the radiator. The problem persisted. Eventually after talking to Porsche of all people the fault was chased back to the engine right bank cylinder head bolts. These apparently stretch allowing exhaust gases into the coolant system. This only manifests itself after driving 40 miles plus when the engine is fully warmed up. Thankfully the dealer took the hit on the chin and paid for the repairs. They also replaced the timing belt and tensioners, which seems sensible, but they weren't obliged to do this. A big chuck up for Hampshire Trading Limited of Alton, Hampshire.