OVERFLOWING OIL

The oil fill cap on top of the pump has a small hole in it to allow crankcase air to expand and contract as the pump heats up and cools.  

If there is too much oil in the pump the oil will splash out the oil filler cap.  Most pumps need to be filled halfway with oil.  The dipstick will show the right level or the oil sight   

For a typical pump cut-a-way view check this out.  

Make sure you replace the pump oil with your pump manufacturers recommended oil.  Usually non-detergent 30 weight oil.  

Another reason for a crankcase to be overfilled is due to a problem with the plunger packings or broken plungers.  This will be evident by a milky color to the oil.  For more discussion on this subject go back to the index.