iambob

Sometimes just filling the cylinder with compressed air at TDC will indicate a problem, is the air leaking trough to the crankcase? or bubbling the coolant? See no bubbling
Are al the coolant hoses going where they should? Sometimes the minor hoses can be connected to the wrong nipples, this can cause interruption to the proper flow. I have spend a long time checking the water flow and pipes - removing checking and flushing. Trying to understand why the flow seems to run the bypass in priority to the radiator at idle. Can only ponder there is some sort of restrictor under the jiggle valve?
Lean fuel/air mixture can cause hot running, check for vacuum leaks, check sensors particularly temp sensors are correct, the wrong plug can be on the wrong sensor, so check all the plugs are on the right sensors. Have checked and replaced ECU temp sensor just in case it was giving wrong reading
Don't assume that anything is correct until its been properly checked. I assume nothing on a MG