Bosch exxcel 7 water hammer

Was this issue ever resolved? I have exactly the same problem with my Hotpoint HE7L252 Experience after bizarrely, the same as gNick, having changed the brushes in the motor. The solenoid on the inlet valve is definitely being activated during the last spin cycle, for around a second each time, quite frequently, as I can feel the pipe pulsing! I have done many repairs to washing machines over the years but have never come across anything as odd as this!

Water hammer should only occur when a washing machine energises the water valve and when the valve shuts off it creates a shock wave that causes loose plumbing pipework to knock. It is normally stopped by finding the loose pipework and securing it properly. Also, it only happens with high water pressure so turning down the mains water pressure in the house usually stops it too.

Having said that the water valve should not be energised at all on the spin cycle. So if these faults are caused by the water valve erroneously activating, possibly repeated times that's a weird fault. Is the motor sparking excessively? Even so water hammer should only happen if you also have high water pressure and loose pipes. Search how to stop water hammer on Google if you haven't already. But I agree that the washing machine shouldn't be causing it on spin. Can you observe that the water valve is being activated when it does it? Can you feel vibrations on the water hose connected to the machine?

You need to use the genuine carbon brushes. The cheap brushes usually work ok but they can be too soft and wear out quickly. They can also coat the inside of the motor in carbon dust which can short it out. If the motor is sparking excessively it's no good, it could be that the armature is worn.

I suspect that it isn't water getting in as it didn't happen straight away.

There wasn't noticeable sparking and it was only happening on the final spin cycle which is a bit odd. There is a lot of carbon dust everywhere, something tell me that cheap brushes are cheap for a reason, and the motor is noisier than it was, especially in reverse. Do you have any recommendations for brushes?

Oddly I laid it down again, to check the motor wiring and gave the connectors into the controller a bit of a wiggle and on the next try the problem had stopped. It will have a proper run tomorrow to see if the problem comes back. It must be something to do with the controller, maybe a relay controlling the valve solenoid?

I might just buy a water hammer arrestor anyway, just in case!