Gorman-Rupp Pumps S4A1-E25 460/3 1396155 and up - Manual (Page 49)

OM-06098 S SERIES PUMPS
PAGE E - 23 MAINTENANCE AND REPAIR
street tee assembly (29). Reinstall and tighten the
cap.
Never attempt to fill the motor cavity
through the drain plug (11) opening or the
oil level plug (17). A volume of air must be
trapped above the motor to permit thermal
expansion of the motor oil.