I have a Kubota ZD 326, and I have a problem that I hope someone can help with. My engine, after running awhile will overheat, the temperature guage moves into the red zone, and then emits a high pitched noise, at which time I immediately kill the motor. This has been reported to the dealer, and he has replaced the thermostat. I have also been diligent about keeping the radiator clean of dust and dirt after each use, and keeping the radiator's overflow reservoir filled with coolant. Has anyone out there had a similar experience, and if so, what did you do about it? Thanks for your help.