Last updated on February 6th, 2017
The following washing machine pump help concerns UK washing machines although the principles should be similar to most appliance pumps. The water pump in a washing machine is one of the most common causes of breakdowns – though more often due to obstructions and blockages.
Where can I buy a washing machine pump?
Make sure you really need to buy one first, the free help and advice on this page may be useful. Don’t just assume if it stops draining water you need a new pump. If you need to replace your washing machine pump you can buy one quickly and easily using 4Washerhelp, which I host for the largest spares company in the UK – Buy washing machine pumps (Next day delivery option available). Using this spares site costs no more than going directly to them but helps support my sites by assigning a small commission to me.
How does a pump work?
The main thing to know is that the pump runs on mains voltage, and spins an impeller round creating a vortex and expelling water out. It’s an extremely simple part.
There are two wires to the field coil on the pump, a live and a neutral. It doesn’t matter which way round they go. Most modern washing machine pumps have plastic fixing brackets so they must be earthed with a separate earth wire (yellow and green) but some pumps don’t need earthing as they are double insulated. If it needs earthing there will be an earth wire close to it and a connector on some metal part of the pump.
A pump is an extremely simple induction motor with an impeller and no serviceable parts. To run the pump the machine just supplies it with power (some may have permanent live feed and be turned on by supplying a neutral return). The pump impeller just spins round and pumps water. It either runs or it doesn’t. The only thing you can check is connections to it, see if the impeller is jammed, or test the continuity of the stator across the two connectors. Do not test anything with the machine connected to the mains.
Can I repair a pump?
Most (UK) washing machine pumps are no longer repairable. If any fault develops, you need to buy a complete pump. An exception is that you can usually buy a pump filter (if fitted) separately. However, the most common cause of a washing machine that wont empty water is an obstruction in the filter or pump, so read the rest of this page for further advice.
What commonly goes wrong with the pump?
The most common problem by far, is an obstruction stopping the pump impeller from spinning, or obstructing water flow into or out of the pump. You can often detect this by listening carefully when putting the washing machine onto spin. Before the motor starts to turn, if you can hear a gentle humming noise, this may be a jammed pump trying to turn. Some obstructions such as socks or a blocked filter don’t stop the impeller from spinning as normal but can prevent or restrict water from flowing through the drain hose. If you have a washing machine full of water and need to drain the water and investigate it follow the instructions on Washing machine won’t drain water
Unusual consequences of an open circuit pump
If the field coil of a water pump goes open circuit, (or the neutral wire becomes detached or broken) then apart from the pump failing to run, the washing machine may not take in any water. This is because the pump sometimes shares the neutral with the water valves. It’s relatively rare for a pump to go open circuit.
Washing machine pumps are prone to leaking. They can then seize up because of corrosion or they can continue to work but just leak. A leaking water pump must be replaced as no seals are available. (Buy washing machine pumps)
Washing machine pumps can become noisy if the bearings fail. Nine times out of ten though, a noisy pump is caused by an obstruction colliding with the rotating impeller. This often manifests itself as a grinding, grating sound that can come and go or be constant (depending on the obstruction). If the noise is due to bearing failure then the pump must be replaced, but check for small obstructions first.
More articles on pumps
This article is one of a series on pumps, check out my others here –
Choose from my list of white goods appliance repairers.