Pentair 355389 left hand thread impeller locking screwPentair Impeller Locking Screw, 355389 In stock$1099
Pentair 355389 left hand thread impeller locking screw
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Pentair Impeller Locking Screw, 355389

Ask a questionMPN 355389
$1099
In stock
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Quick overview

  • Left hand thread It backs out clockwise, the opposite of an ordinary fastener, which is what catches people out.
  • Genuine Pentair Factory part 355389.
  • Holds the impeller on the shaft The screw locks the impeller to the motor shaft so it cannot work loose in service.
  • Challenger and SuperFlo Listed for Pentair Challenger and Pentair SuperFlo pumps.
  • Cheap part, expensive failure A stripped or missing locking screw lets the impeller move and takes the pump performance with it.
  • Worth renewing on a rebuild Small enough to replace as a matter of course any time the impeller comes off.
Full description and specifications ↓

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Product details

The Pentair 355389 is the impeller locking screw for Pentair Challenger and SuperFlo pool pumps. It is left hand threaded, and it is the genuine Pentair part.

Left hand thread

The screw is deliberately reverse threaded, so the impeller cannot unscrew itself as the motor spins. That also means it loosens clockwise. More than one of these has been rounded off by someone leaning hard on it the wrong way, so get the direction right before you put weight on the tool.

What it does

The screw locks the impeller onto the motor shaft. If it strips, backs out or is left out after a rebuild, the impeller can shift on the shaft, and the pump loses flow and starts making noise long before anyone thinks to look at a single small screw.

When to replace it

Any time the impeller comes off, for a mechanical seal or for a rebuild, look at the screw before it goes back in. A screw with a damaged head or worn threads is not worth reusing.

From Pool School

How to Prime a Pool PumpFrom the breaker to a full pot, each manufacturer's time limit, and what to check when it won't catch prime. Read Replace the Pool Pump Motor or the Whole Pump?The manufacturers' tests first, what each repair replaces, and the federal motor rule. Read

Where this part goes

21 Key 21 on the Pentair SuperFlo PumpFits every model in the drawing.See it on the diagramAll Pentair SuperFlo Pump Parts 38 parts and the drawing10 Key 10 on the Pentair Challenger PumpFits every model in the drawing.See it on the diagramAll Pentair Challenger Pump Parts 48 parts and the drawing
Specifications
Brand Pentair
Manufacturer part number 355389
UPC 788379699291
Type Impeller locking screw
Thread Left hand
Part type Pool pump part
Fits Pentair Challenger, Pentair SuperFlo
Shipping weight 0.02 lb
Ships Parcel

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Questions and answers

What people ask about this product, answered by our pool techs.

Which way does it undo?
It is left hand threaded, so it loosens clockwise and tightens counterclockwise. Turning it the normal way only makes it tighter.
Which pumps use this screw?
Pentair lists it for the Challenger and the SuperFlo pool pumps.
Is it a genuine Pentair part?
Yes. It is Pentair OEM part 355389.
Do I need one if I am only changing the seal?
The impeller has to come off to reach the mechanical seal, so the locking screw comes out either way. It is worth having a fresh one on hand in case the old one is chewed up.
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