310A johndeere blowing dip stick out

A friend of mine told me were a 1980 310A jd back hoe clean no dents pins tight paint in great condition, has been setting for around three years in a shed, decided to go see it talked with the owner, the had bought it to use on farm and did for a while then started to use oil, had it over hauled and when they tried to use it would blow the dip stick outof the engine, they got tired of it and parked it in the shed, when i went to see it can turn engine over, just wonder what you guys thought would cause that, i bought it cheap enough to triple my money by parting it out thanks

310A johndeere blowing dip stick out