The tractor has 9500 hours. Bearings were rolled in at 5200 hours. The coolant level drops about a quart per 10 hours of usage. It uses no oil, and the coolant doesn’t appear to be going into the crankcase. The tractor does not get hot at all.
It does have some blowby but probably not excessive and not all the time. There is some clear water dripping from the blowby tube occasionally, but this looks more like condensation than antifreeze. There is no smoke out of the exhaust other than what would be considered normal - a good puff of black smoke at start-up but nothing really otherwise.
I can’t see where there is any external coolant leak unless it’s seeping out of something and burning off. Is it time to think about an overhaul, or is it possibly something else where we could get a few more thousand hours out of it?