I have a 96 Ranger Engine 4.0 OHV. I had the motor rebuilt a year ago by FORD and now it has to much pressure in the radiator. It is cracking the radiator, which causes a leak.I have gone through 3 Radiator's which cost me $600.00.Ford is unable to help me. I know I do not have a cylinder head problem because I Had them replace everything and I still have my old cylinder heads n stuff. Temperature gauge is going up half way and coming down to cool. I replaced the Thermostat again to see if that is the problem. Pressure is stuck on the upper return line back to the Radiator. I have to manually release pressure when the vehicle is off by opening the cap a little to let water go to the reserve tank. I have also replaced the Radiator Cap. Everything is OEM what is wrong with it? Anybody?