Bosch Exxcel Dishwasher SGS53 - Top Spray Arm Not Working

[TonyFixit]

Please can anyone help. The top spray arm is not rotating in my dishwasher. Became aware when dishes were not cleaned and were covered in a gritty deposit. Fills and pumps out with no problem.

Plot thickens! I have done a bit more investigation and peered down the hole in the sump unit that feeds the top spray arm. There appears to be a shutter valve arrangement. I fiddled a little bit to see if it moved - it did a little. Then I put the fittings back in and switched on the machine. Amazingly the top spray arm rotated but now the bottom one didn't . Oh well that rules out a problem with the top spray arm. Then I reset the wash cycle and tried again - now the top spray arm stopped working and the bottom one worked again - now I am really confused!!

Had a look on the Bosch parts website (https://www.bosch-eshop.com/eshop(bD1lbiZjPTAwOQ==)/bosch/gb/prodp.htm?prod=SGS53A02GB%2f38) and this shutter valve appears to be part of the water heater - refered to as an alternating water distributer. Not sure if this is faulty or whether it is a problem with the controller. may do a bit more investigation but may just give up and get a new machine - not worth the cost of repair.... unless anyone out ther knows differently!!!

 

[Fudgeit]

In case anybody else finds this thread - Having had a similar problem but with the lower basket - I have just replaced the Instantaneous Water heater element that contains the rotating divertor disc. The divertor disc is driven by a series of Nylon gears and in my case the teeth on the spindle which drives the disc had sheard off -

I have added a couple of pictures of the offending bits.

To replace this is not an easy job - 3/4 hours

Bosch sell the replacement part £83 ish plus VAT.

 

[smokin750]

I realize that i am replying to an old post but recently had this problem.
It is caused by the divert valve in the heater unit buried in the bowels of the machine not working, in my case it had burnt all the contacts out.
I replaced the unit at a cost of £107 to find it still did not work, further investigation i found it had taken out a transistor on the control board that would be another £114 which is getting towards the price of a new machine.
I managed to get a replacement transistor from RS (NXP
PZT2222A,115, NPN Bipolar Transistor, 0.6A 40V HFE:35V 300MHz Power, 4-Pin SC-73) at a cost of 27p each, got 4 in case a damaged it putting it in, i didn't but it was fiddley and now the machine works perfectly.
So before you lash out on a heater pump check the control board which is an easy job.
Hope this helps.