Hi, I am the owner of a 2007 Sorento Auto diesel XS for the last 3 years.For all of that time I have had problems towing my caravan. I can only visit sites via flat roads, once I encounter hills the engine overheats and lacks power. I have tried many ways to have this sorted, the main dealer I bought it off has examined the car on two occasions and have said there is nothing wrong with the car. Diagnostic tests show no faults and I have only this last week replaced the engine fan in the hope that was the problem. This morning I took the caravan up a steep gradient and it overheated immediately. The strange thing is, as soon as I stop in a lay bye etc it cools down almost immediately. The only thing I have now considered is perhaps the water pump is defective when the engine is under load. Can anyone help me out who may have had a similar problem. Any help would be much appreciated.