Washing Machine Overfilling

If a washing machine is overfilling with water you should be able to see that the water line inside the drum has gone much higher than normal or has gone completely up to the top of the door glass. Eventually water will start pouring out of the soap dispenser drawer and / or out of the back. However, if the water levels seem normal and the washer is spinning when water is thrown out it could be a different fault.

If the washing machine is definitely overfilling then turn it off. If water continues to enter the washing machine then either the hot or the cold water valve must be jammed open. In this situation the water must be turned off at the taps. They should be at the side of the washing machine, but many are fitted under the sink. Some water taps are wrongly situated behind the washing machine where you can’t get at them properly. If this is the case you will have to try and ease the washing machine out.

If it stops filling as soon as you switch the washing machine off then the fault is with the pressure system that controls the water levels.

An overfilling washing machine is commonly caused by a blockage of grease and gunge in the pressure chamber, or more rarely a faulty pressure switch. Another possible (rarer) cause is a hole in the small pressure chamber tubing (which links the pressure chamber and pressure switch) can cause overfilling as air leaks from the system. Pressure system faults can be tricky to deal with, and the consequences of overfilling can be serious.

Troubleshooting an overfilling washing machine

I can’t give specific repair instructions but if you understand how the water levels are controlled you may be able to work out what’s causing the problem. Here’s how most washing machines control the water levels. The picture to the left is of an old pressure switch, they are much smaller these days but all pressure switches have a small diameter rubber or plastic tubing connected at the bottom. (For a picture of a modern pressure switch see here – faults on pressure system)

1. There is a pressure switch, which is a small device with several wires on it. This part is always at the top of the machine under the lid. It’s usually round. It’s a simple air pressure operated switch and some have just 1 level switching, and others have 2 or 3 level switching (different switches operating at different air pressures)
2. At the bottom of this pressure switch is a plastic or rubber tubing hose.
3. This hose runs down to a pressure chamber which is a plastic housing fitted to the tub.
4. As water enters the washing machine, it also enters the pressure chamber housing
5. As the level of the water rises, it enters the pressure chamber and forces air up the tubing. When sufficient air pressure is reached, the pressure switch will switch on. (Conversely, when the water is pumped away, the air pressure should release and cause the pressure switch to switch back off.)
6. This then cuts the power to the water valves and passes it on to the timer which starts washing.

Common faults on the pressure system

The pressure switch itself can become faulty or stuck in an on position although this is the last thing I would suspect not the first. Common faults are partial blockages of grease and gunge in the pressure chamber bottle either stopping water getting inside it to force air up the tube or (more commonly) letting water in but trapping it so that when water is pumped away the air pressure is trapped keeping the pressure switch on, thus preventing the washer from getting the signal that water has been pumped away ok. In such cases the symptoms would be no spin. If air leaks from the small pressure tubing it will cause overfilling due to loss of air pressure.

Related articles:

Both the sections above are covered in these two articles – How washing machines control water levels | Faults on pressure systems

Similar faults:

Washing machine fills but empties down the drain at same time

If water is running down the drain (or being pumped out of the machine) but it’s filling at the same time it could be caused by a fault described here – Washing machine fills and drains at the same time

Washing machine fills with water when off

If water runs into the washing machine when it isn’t even running try this article Washing machine fills with water when off

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