Description

The Polaris P85 is the seal plate housing o-ring for the PB4-60Q Halcyon booster pump. It is the genuine Polaris part.

What it seals

The wet end of the booster pump is two pieces, the volute and the seal plate, drawn together around this o-ring. Everything the pump pushes toward the cleaner passes through that joint, so a ring that has flattened, hardened or been nicked on reassembly shows up as a steady drip or a spray from the seam between the two halves.

Fitting

Fit a fresh o-ring any time the housing is opened. An o-ring that has taken the shape of the groove will not reseal reliably once it has been disturbed, and it is the cheapest part in the pump. While the wet end is apart, look at the shaft seal too, since replacing both together avoids a second teardown.