My diesel 97 XJ overheated the other day due to a failed water pump, mechanic replaced it and all appeared fine.
Have made two journeys since: First time after about two miles the heater started blowing cold and the temperature gauge climbed towards red so pulled over and switched off. Restarted after 5 minutes and everything was fine continued journey home of 15 miles without problem.
This morning drove in to work, sat in traffic with no problem. Then with a few miles to go on an open road same thing, waited five minutes again and again all back to normal.
No steam or dramatics, just cold blower and temperature gauge climbing.
Any ideas, thinking air in the system or faulty thermostat?