first,you will have bubbles of air in your cooling system, gas leakage through the liner to the jacket water rising the temperature of the water . you might have water to your crankcase in case if the engine stopped.
diesel isn't cracked, but a heavy oil fraction is cracked to obtain diesel
The cause of white puffing smoke in a diesel is the crack pipe ventilator seal. Fix that it keeps the crack inside.
up your mamas faj crack
There is likely a crack in the engine block.
can crack the engine.
If ice forms anywhere in the engine, it can crack the block.
crack the engine block and oil mixes with water or antifreeze.
You can blow a head gasket or the head can crack or be warped.
Normaly by the frost plugs seizing and the engine splitting the cylinder walls during thermal expansion of ice in the cooling jackets
It could be a hairline crack in the head gasket between cylinder 2 & 3.
It would help to know which model of Kubota engine, and also the application, as small Kubota diesels are used by a number of third party manufacturers for thing such as worksite lighting, crack seal tar pots, etc.
The engine overheats and parts can melt, crack, even explode (massive expansion due to heat.)