Check the coolant pump for any base gasket material lying around it. When they strip, usually only three reasons:
Something stopped the coolant pump, Something stopped the rotary valve or the injection pump jammed. When reinstalling the shaft, use some tightly wound electrical tape well greased around the coolant pump end's threads and step to protect the oil cavity and coolant seals when pushing the shaft back in. Grease up the rotary end seal too.