Also when its overheating, make sure both hoses are warm...if the top hose is cold, and there's no thermostat in, then you have a blockage in the system...usually in the heater core...you can try bypassing the heater core...connect the heater hoses to each port on the back. then if it runs at normal operating temp...you know where the blockage is. Lately the clutch mechanism has been going out on 240's...heard about a lot of them. waterpump could be the culprit...but also feel different areas of the radiator...i got a brand new radiator, and there was a blockage in it, which had me stumped for a month or so.