how can i fix a tractor water system that boils the water while running?

Anti freeze has lubricating properties on rubber components and may cause a water leak.
Check all hose connections any water coming from the gland seal on the waterpump also radiator cap seal.

Also in draining the system you may have caused an air lock squeeze the bottom hose with the radiator cap off to release air as the engine warms up (WATCH OUT FOR THE COOLING FAN BLADES)

Also thermostat may have stuck closed. Suggest that system is flushed through.

Maurice
March 2010