Coolant Question JD 310C

Have owned 1990 John Deere 310C for a month now and have noticed that each time I check the machine prior to use for day I am having to add a little less than a gallon of coolant in order to get the level to the top of the filler neck. Then as I operate the machine in the first hour or so I watch the radiator puke out all of the coolant I just added via the overflow tube (no overflow tank). At $10 per gallon of coolant this could become a bit pricey over time. The coolant capacity of the machine as outfitted is 14 quarts (3.5 gallons) and I am having to add at least 3 to 3.5 quarts each time I use it. There is no coolant in the engine oil so I believe the system is purging all of the added out onto the ground. Anyone else had a similar experience? I have replaced radiator cap with NOS JD part (7 PSI). I am going to add a temp gauge and see how she runs being down 3 quarts and if she runs in an acceptable temp range then maybe that is the level that the machine "wants" to be at.



Thanks

Coolant Question JD 310C