I thought that,but yesterday i checked the feed and return hoses for the heater and the feed was hot,but return was only luke warm,my temp gauge didnt go above 90o however i went on a 20 mile journey tonight the temp shot up to 130o on the way back, so i pulled over eased the header tank cap off and all i could hear was the heater hoses gurgling and a lot of pressure was in the tank,there is no oil in the water or water in the oil,so im just hoping it will be the stat, i will have to remove it tomorrow
