oil in radiator

[Dave-HT]

I have an Kobelco Sk50UR with a Yanmar 3TN100L-YB engine. I have a lot of oil in the radiator. I see no water in the oil. Does not appear to be using oil. A lot of oil is about 1 or more inches in the top of the radiator and the overflow container is full. Also, just noticed a coolant leak by the gear box next to the water pump. Possible causes? Just purchased the unit and not sure how long the problem has been going on.

 

[Aaron-HT]

I'm not familiar with that engine but on a Yanmar tractor engine that would usually be a sign of a blown head gasket or cracked head or block. Gaskets normally fail between compression and water ports but they can also fail between oil and water ports. Oil is usually under more pressure than the coolant so if there is a leak between the oil and water ports- the oil wins. I'm not sure if that engine has an oil cooler but that might also be a good place to check.

Coolant leaking from the head area could also be an indication of a blown head gasket.

Do you get any bubbles in the radiator when the engine is running?

 

[4x4_Welder-HT]

If there is an oil cooler that is the first place I would look. The oil is under higher pressure than the coolant, and will force through a smaller crack than the coolant can.