Bobcat 341 Mini Excavator Kubota Engine, oil in radiator?

Need a bit of trouble shooting help. I have a 2003 bobcat 341 Mini Excavator with a Kubota v2003 motor, found oil in radiator, did pressure test through radiator and pressure drops from 15psi down to about 10psi then stops, does not build pressure while running after pumping up to 15psi, I have no water in the oil pan, while under pressure pull dip stick and nothing changes,
wondering if it could be a head gasket or a cracked liner, if you have knowledge of kubota diesels, any input would be great.

Thanks
Chris

Bobcat 341 Mini Excavator Kubota Engine, oil in radiator?