Recently replaced head gaskets on 96 Disco. Replaced thermostat also. When driving, coolant increases in volume and pressure. Temp gauge remains in normal mid range but engine is obviously getting hot with high pressure and volume. A/C works fine and blows cold. Fan has minimal resistance when shutdown and engine warm. Electric fans don't appear to be working at all. Do they have a fuse or relay and where is the sensor to turn them on? Also I tried some of that head gasket leak stop before changing gaskets. Could that have fouled the radiator? Can I change the fan clutch with normal tools? Can I hot wire electric fans to battery? Truck has 240000 miles so not really interested in spending a ton of money. Any ideas?