[GordMay]

Yes a good coolant will help - actually reduce operating temperature.
Tight Cutless Bearing will increase load, so temperature.
Fuel Injector Timing & Valve Timing can effect temperature.
Boiling does not remove calcium from heat exchanger. Check for good water discharge, then visual inspection of intercooler tubes (difficult).
Some troubleshooting advice.
Check Temperature Guage - is it actually running hot?
Check Thermostat - opening?
Water Pump belt too loose?
Air Cleaner clean and unrestricted induction manifold?
Cylinder Head gasket OK - no leaks, look for uneven cylinder compression.
Try an internet search on Perkins - I saw some excellent troubleshooting guides somewhere (sorry didn''t bookmark it).
Good Luck!
Gord