Farmall 300 coolant in oil

Hello,
I recently acquired a Farmall 300 which had been sitting outside for 7 or 8 years. It is a one owner tractor and was always well taken care of. At some point while it was sitting outside, the can over the exhaust blew off and water got into the engine. When we started working on it, we took out the spark plugs and cranked it over a few times to clear out the water. At this point the oil was free of water. We then added coolant (the radiator leaks and it had all drained out) and started the tractor. Started on the first crank. We only ran it for a few minutes, but while it was running there was water coming out the exhaust, which may or may not have been left over rainwater. Left the tractor for about a week, then came back and checked the oil. A white coolant/oil mix. When I took the oil plug out, over 5 gallons of oil/water came out, while only about a gallon of coolant came out of the radiator drain. Thinking head gasket, removed the head (bolts seemed somewhat loose?) and found the gasket intact. Had the head pressure tested and found no cracks, but did find two stuck valves. There are no visible cracks on the block or the sleeves. Could it be that the head loosened up from sitting? Or could the block really have cracked from water freezing in it?

-Eric

The tractor was parked and the head bolts were loose for a reason.

If it's dumping all the coolant into the oil pan, it must be a pretty severe leak that you should be able to pinpoint by simply removing the oil pan and filling the radiator.

It was a relatives tractor that was parked because there was no longer a use for it. It was running fine when it was parked.

Is it possible that a cracked block would allow all of the coolant to pass through into the crankcase? The oil almost seemed like it was under a bit of pressure when I pulled the plug

Entirely possible the block could be cracked and dumping the water into the oil.

5 gallons of water in the crankcase pretty well fills it up, and just the "head" from that much of a column of liquid is pretty a pretty good pressure. AFAIK, there is a breather on the crankcase that would prevent any pressure buildup unless it is plugged.

If it is a large enough crack to allow that much water into the crankcase, wouldn't there also be oil pushed into the radiator? When I drained the radiator it was only water and antifreeze.