Plainwire / Guides / Washer drain pump
Washer drain pump
Symptom: the machine fills, washes, and then sits with a drum full of water, usually with an error code and usually without spinning. Nine times out of ten the pump is fine and something in front of it is not, so this guide is mostly about not buying a pump.
Work the path in order
Water leaves the drum through the sump, passes the filter, goes through the pump, and rises through a hose to a high point before falling to the standpipe. A blockage anywhere in that chain produces exactly the same symptom.
- The filter. Behind the small hatch at the bottom front. Put a shallow tray and two towels down first — there are several litres in there and it comes out faster than you expect. Coins, hair grips, and the wire from an underwired bra are the classic three.
- The pump impeller, through the filter opening. With the filter out you can usually reach the impeller with a finger. It should spin freely with a light magnetic detent. If it is locked solid, something is wound around the shaft, and that something is almost always thread.
- The drain hose. Pull it off the standpipe and lower the end into a bucket below the machine level. If water siphons out freely, the hose is clear and the fault is upstream. If nothing comes, the hose is blocked or kinked behind the machine.
- The standpipe itself. A partially blocked standpipe drains slowly enough that the machine times out. Pour four litres of water down it quickly and watch whether it backs up.
Unplug the machine at the wall and turn off the inlet tap. Do not work on a machine that is plugged in because you want to run a cycle to test it — test with the panels back on.
Testing the pump properly
If the path is clear and it still will not drain, the pump can be tested two ways without a multimeter and one way with.
| Test | Result | Reading |
|---|---|---|
| Listen at the start of the drain phase | A hum with no water movement | Motor is energised, impeller obstructed or seized |
| Listen at the start of the drain phase | Silence | No supply reaching the pump, or an open winding |
| Resistance across the pump terminals, disconnected | Typically 150–250 Ω on a 230 V synchronous pump | Open circuit means a failed winding; near zero means a shorted one |
The middle case is the one people misread. Silence usually means the machine has not asked the pump to run, and that points at the pressure switch or its hose rather than at the pump. A pressure-switch hose with a hairline split tells the control board the drum is already empty, so it never commissions a drain.
The pressure switch hose
It is a thin clear tube running from the bottom of the sump up the side of the cabinet to a small round switch near the top. Detach the upper end, blow gently down it, and listen for a click from the switch. No click means either a split hose or a dead switch, and the hose costs almost nothing. Check the lower end for the sludge that accumulates there; it blocks the tube completely and reads as an empty drum.
If it really is the pump
Most drain pumps are a two-part design: a motor that twists off the volute with a quarter turn, and a volute that stays attached to the sump hose. Where that is true you replace the motor only, you do not have to break the plumbing, and the part is a fraction of the price of the assembly. Look for three lugs and an arrow moulded into the plastic before you start undoing hose clips.
Match the part by the number on the motor body, not by the machine model. Two machines with the same badge and the same model number, eighteen months apart, will often have different pumps.
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