Bosch dishwasher SHV55M03GB/40 spraybars don't turn

This dishwasher is 7 years old and 2 months ago started leaving dishes dirty because the lower spraybar was not rotating when the circulating pump was operating. I cleaned filters, checked the drain pump was clear, checked the water passages to the spraybars were clear and not leaking, checked all spraybar nozzles were clear. All nozzles were spraying water but the lower bar did not turn. I drilled an extra rearward-facing hole in each end of the lower spraybar and it then whizzed round, problem solved. Now the problem has returned, this time neither spraybar rotates although a lot of water squirts from all the nozzles. Tried pouring extra water in to make sure it wasn't due to low water level. The circulating pump is obviously running and sounds normal. Is it possible that the pump has just got inefficient and is not delivering enough water? I'd like to be sure before spending 150 quid on a new pump. Has anyone heard of this before?

You may have reduced circulation due to a clogged up pressure chamber
and transfer pipe to the sump.

Power off and remove lid,lhs panel(two screws door frame)lower plinth
and metal plate.

You should see a pipe running from the pressure chamber to the sump.
This tends to crud up leading to poor circulation.

You need to remove and clean the offending parts........


You may have other blockages but I doubt it is a problem with the circulation motor.

There is a small motor within the heater housing which acts like a shutter
diverting the flow to upper and lower arms.

When this fails it usually means all the flow is on one arm only.
This can be changed but is not an average DIY imho,usually the complete
heater assembly is swapped I think. Cost is pretty high.
It is common that the motor leaks at the sump which is difficult to see.
You will soon see if there is much water in the base though.....


There are diagrams which can help on the Bosch site

https://www.bosch-eshop.com/eshop(b...h/gb/prodp.htm?prod=SHV55M03GB/40&ESHOPTYPE=A

Thanks, good advice. Yesterday a service engineer looked at the machine, doesn't think the pump is faulty, suspects the heater unit shutter valve - but it sprays from both arms! Will check the pressure vessel pipe and let you know the result.

The service engineer was right - the motorised valve in the heater unit, which reduces or shuts off the flow to one or other spraybar (why?) was faulty. The gear which drives the shutter valve disc was corroded and the end of its shaft had broken off, so that the disc stopped in a position where very little water flowed to the spraybars. Why had the nylon gear material corroded so badly? Apparently it's a common problem. Wrong sort of plastic, Mr Bosch? See photo. No parts available, of course - the complete heater unit has to be replaced for 99 pounds plus fitting plus VAT. Hope this helps anyone with the same problem.

Yes it is a fairly common problem. Bosch call their system "water points" for some strange reason. Both spray arms do not spray/rotate at the same time (yours did because the water points were busted). The bottom arm sprays water/detergent for 60secs then the top spray arm sprays for 55secs (there is a 5 second changeover period). A synchronous motor, gear/cam system, & micro-switch control the spray arm sequences. The "water points" are part of the instantaneous water heater & unfortunately the whole unit has to be changed out in the event of a failure http://www.espares.co.uk/parts?k=483058. There is nothing wrong with the plastic used, this problem is more often than not caused by a leaking seal allowing water into the works. In my opinion the attending engineer performed an outstanding job in diagnosing the problem. It isn't the easiest or cheapest repair.

Pete32 said:

The service engineer was right - the motorised valve in the heater unit, which reduces or shuts off the flow to one or other spraybar (why?) was faulty. The gear which drives the shutter valve disc was corroded and the end of its shaft had broken off, so that the disc stopped in a position where very little water flowed to the spraybars. Why had the nylon gear material corroded so badly? Apparently it's a common problem. Wrong sort of plastic, Mr Bosch? See photo. No parts available, of course - the complete heater unit has to be replaced for 99 pounds plus fitting plus VAT. Hope this helps anyone with the same problem.

Click to expand...

Hi Pete,

Im really hoping you will see this! I think my dishwasher has this problem and needs the 'instantaneous water heater' assembly replacing. Megabucks at £90+ but we are hoping to do it ourselves. Can you give me any ideas on what the repairman did? how did he access the assembly? Did he have to remove the inner lining of the machine or can you get to it underneath?? How long did the repair take? From what I can make out this repair isn't easy but would a competent engineer (not dishwasher specialist) with a willing helper be able to do it do you think? What was your total cost for the repair by the engineer? Thanks!

Wondering if ZIPPER is out there as you really know what you are doing! Any advice would be really appreciated. Christmas and I am not looking forward to all those dishes....

~It's the lower arm that isn't turning on mine (Siemens aka Bosch)

Total cost was 99 for the part plus 65 engineer's charge plus VAT, just under 200 but still cheaper than a new machine and it's working fine now. I would certainly replace it myself next time although it's quite a big job. Mine is a built-in, so the work may be slightly different on a free-standing unit. Disconnect, drain as much water as possible, turn it upside down, remove the sides and bottom tray. Make notes of all wiring connections, then disconnect and remove parts as necessary until the heater can be removed. Not really difficult, no special tools needed. Do check again that nothing is blocking the spraybar holes, particularly the angled one at the end - after my repair was done, the top arm didn't turn well because there was a bean husk or something blocking an end hole, which was very difficult to remove. Good luck!

Pete wisely suggested checking if the spray arm(s) are blocked. They often get choked up by pips & other interesting garbage. Of course the "water points" could have gone awol but always it pays to rule out the simple things before undertaking a somewhat time consuming & expensive repair. If all is well with the spray arms post again with the machine "E number" & I'll give you a "step by step" for changing out the instantaneous water heater assy (should that prove necessary). It isn't as difficult as it sounds

Ah, Pete33, Zipper,

Wish I had seen your helpful replies before we decided to start taking the machine apart! We are in the process of dismantling right now.

Last week I checked the spray arm and found pips (3 or 4 so I triumphantly thought I had brilliantly fixed the machine....... No such luck! I also managed to 'fool' the machine into letting me keep the door open whilst I watched the rotors (soaking myself and floor in process - didn't see anything I hadn't already guessed). Unfortunately I couldn't then work out how to unlock the door mechanism to shut the door and ended taking the whole door apart only to work out that I just need to pull on the lock with pliers - duh (but I am the opposite sex so I guess you will make a huge allowance....). Door locked itself on me too................. aargh. Door eventually resurrected - and it all still worked.

So we have managed to get the sides and bottom off - that is a job in itself! The main filter (fan like structure) looks to be full of gunk so we are now going to try to get into that too...... the local repair shop did say I could bring it in to them if it all goes wrong.....

First son made a comment this am about how we really did need to get it fixed in time for Christmas ie nothing along the lines of 'don't worry, we can all help out with the washing up and it won't be a problem'. Second son, who never puts any of his plates in the dishwasher finally decided to change the habit of a life time and has been loading the dead dishwasher - how ironic.

Will let you know how we get on. Wish I had your instructions Zipper. Float mechanism has fallen off but think we know where that goes.........

Here is the promised update....................

It works!!!!

When I decided that it was the alternating flow mechanism that was broken I started to make calls, first to locate one 'off the shelf' and secondly to find the best price! My local shop were interesting. They have had a recent epidemic of dishwashers with the same problem. Fortunately for their other customers, the models involved could just have the flow mechanism changed only one customer had had to have the whole instantaneous water heater unit replaced). My Siemens just happens to be the odd one out in that it needed the whole instantaneous water heater unit changing just to replace the flow mechanism...... Nice little earner Siemens. Cost £96 from Siemens spare parts. Went for them because the cost included delivery and had we found a blockage instead, I would have been able to return the spare part and received a full refund bar the postage to return it. Some shops charge a whopping 30% restocking fee. Ouch.

So, it is, as you said, not an easy job. Even more difficult if you are working without any manual/instructions. Took a while, lots of cussing too. Float came off more than once even with sticky tape to hold it in place (on the outside so we could remove it when finished). Put the base back on only to realise we had forgotten the door pulley mechanism. Pump kept dropping off its rubber cradle (probably could have done then last when we had turned the machine back onto its feet). Would we do it again? Yes - we know what we are doing now!!

It's working too. The bottom rotor turns nicely. I am thnking that there are parts to salvage off the water heater assembly so will put that away just in case.....

So, in my last post I mentioned that we were trying to get into the water softener (I think that is what it is) as the filter inside seemed to be gummed up. Anyone know if that is normal or just how the salt looks? By the way, we couldn't get into it as we didn't have a tool to undo the nut on the inside of the machine (salt filler cap etc).

Does anyone know what we can use to run a really good clean through the machine? Something stronger than the supermarket dishwasher cleaning stuff?

Thanks for your offer to help Zipper, very kind. If anyone made it this far in this post - great!

Distiled White vinegar just a pint on the hottest setting.

Hey Rocks, that was a quick reply! Great, thanks. We thought vinegar might be the thing. Will give it a go.

I am so sorry....your recent postings passed right by me somehow. But it looks like you did a great job all on your own anyhow...congratulations

But in the event just the cog needs replacing i.e sheared off where it attaches to the water flow disk ( the part with holes to divert the water) , how do you re-align the cog to the disk????

Obviously the position of the disk is crucial to the correct operation of the dishwasher.
Thanks, would greatly appreciate help with this one.

Sorry, it was 5 years ago and I can't remember the details now, but I don't think the gear position matters - as it rotates it directs water first to one spraybar for about 50 seconds, then the other for the same time, then just repeats so I don't think it matters where it starts from. Could be wrong, make a note of the gear teeth meshing before removal. Or perhaps an expert out there can advise?