Description

The Pentair 39300600 is the locking lid o-ring for the American Products Ultra Flo pump. It measures 6-1/2 in. across the inside with a 1/4 in. cross section, and it is molded in rubber, the same as the original.

Check your build date first

Pentair changed the lid on this pump in late 1994. This ring is for Ultra Flo pumps built after 11/94. Pumps built before that date take Pentair 39300300, which is a different size, so confirm which side of the change your pump falls on before ordering.

What it does

The o-ring seals the locking lid to the pump body. On the suction side of the system that seal is under vacuum, so when the ring hardens, flattens or cracks the pump starts drawing air instead of water. The usual symptoms are a pump that will not hold prime and air collecting in the strainer basket. Wipe the groove clean, fit the new ring, and use a silicone o-ring lubricant to help it seat.