Having just spent about £ 800 trying to cure over heating problems on our 98Paul Smith unnecessarily I thought I would suggest ways to approach MPI overheating. Symptoms were expansion tank boiling over with guage halfway on normal and without fan coming on. A pyrometer check showed that temperature in the sensor never got high enough to turn on fan ( 105 degrees ) so we assumed head gasket failure and spent a lot of time and money removing and replacing the head needlessly.
Best approach seems :
1. check electric fan removing temp sensor lead should turn fan on if nec upgrade sensor connection with minispares rover upgrade
2. replace expansion tank cap with minispares one if this doesnt cure the problem
3. check / change thermostat for correct 88 degree one
4. Change radiator only about £ 70 from minispares if that doesnt work only then check head gasket, head gasket failure is rare on these engines.
We had exactly the same problem on our 1998 Sportspack which boiled over within 5 minutes of starting again with the temp guage only halfway, we changed the expansion tank cap no better and then the radiator and no problems after that , so it seems the radiators can be a problem
