We seem to have two conversations and two problems in the same thread -- Whichever poster is overheating -- Don't forget the heater core(s). If there is corrosion in it making its way to the primary system, that can cause a lot of problems. And some buses have more than one. Heater hoses and radiator cap are also oft-overlooked items. A bad radiator cap won't hold pressure, which won't allow the system to maintain pressure, thereby losing the ability to hold temperature.
For an IH SV engine to cool properly, you MUST use the correct robertshaw type thermostat, it has a disc on the bottom that blocks the bypass as it opens, if the stat does not have that, the engine will run hot.
Linear Mode
