Bosch DW Puzzle

[sudsmaster]

I picked up a Bosch SHU4306 dishwasher over the weekend. The price was right: free. But upon closer inspection, it's apparent something is amiss with the unit. For one, it reeked and had what looked like mold growing in it. I took it outside and took the racks etc out and gave them a cleaning in my SHU430C, which works fine. Then I hosed out the freebie and hooked it up to a garden hose for water, and gave it power.

The previous owner had said it wasn't draining right, that it was damp after a wash, but it drains and recirculates just fine. But it doesn't heat the water, and never came off wash after about 1 1/2 hours.

I'm guessing the heating element needs replacing... unless the machine insists on having hot water, which I doubt, since there's no way to predict if a customer is going to have a water heater right next to a dishwasher and of course hot water cools down in the pipes. Plus the DW uses so little water the hot water from the water heater might never get to it.

Is my guess correct, or does the Bosch design refuse to heat water unless it's already at a certain temp?

Already priced out replacement heating elements... about $100 on-line. I might just wind up using this machine for "parts".

 

[bingwsguy]

sudsmaster

My Bosch is model SHU9952UC and since it is on the second floor of the house and it uses so little water, I have it plumbed to the cold water line. It will heat water from cold all the way up to around 160 degrees. I would guess that all of their models function the same? Sounds like it is the element, but aren't they awesome dishwashers?

 

[super32]

control unit

Get into the control panel and remove the control board. Carefully open the case and look on the back of the board with the relay unit on it. You should see a burnt soulder (sp)? connection almost dead center of the board. It will be on the opposite side of the largest relay on the board, which happens to be the heat relay. You can re-soulder the connection but it will eventually burn again or the board may go haywire if it hasnt already. Those unit were notorious for burnt relay problems.

Also if this proves to be the problem go back to the original owner and find out when it was purchased. That model should have have had 5yrs on its control unit. Just a thought.

Scott

 

[sudsmaster]

Scott,

Thanks a bunch for the information.

As it happens, as I was looking at the owner's manual, a service receipt dropped out. The control board was replaced in 2001... unfortunately the date is written as "0/0301" so it's anybody's guess as to what month that was! Anyway, it says the control unit #264461 was replaced uner warranty. It also lists the heater #264462 and thermister #165281, but these were crossed out so I assume they were not replaced. There was a $30 service charge. "Service performed: Replace Control".

So I'll take apart the control panel and see if there is a burnt solder connection. I'm thinking you're right, this was a bad design and failed repeatedly... but maybe Bosch upgraded the controls, eventually, to make them more robust (ala Maytag)?

 

[sudsmaster]

PS-Is it the relay that is the problem? What about putting in a better relay?

The machine seems to work ok other than not heating or advancing beyond wash. That is, it drains ok at the start of the cycle, adds water properly, and washes its little heart out. But Mr. Bosch is a cold fish. I was also able to cancel the cycle and put it into Rinse/hold so I could drain it and put it away for the night. So I'm thinking the control board is still ok other than for the burnt heater relay.

BTW, I had a not totally unrelated experience with my '78 Dodge pickup truck. It was running poorly, and stalling at night at stop lights. Turned out that the entire electrics for the car run through the ammeter on the dash. That would be fine, except he ammeter is held in place on a plastic panel. The ammeter connections had loosened over time, which caused heating, which melted the plastic, which further loosened the connections, until it sometimes wouldn't start at all. I fixed it by adding some nuts to the ammeter studs and very firmly connection the main circuit wires between two nuts, instead of between one nut and unreliable plastic.

Perhaps the Bosch has a similar issue?

 

[super32]

replacement parts

Bewear, Replacement parts typicaly only carry a one year warranty. My comment about 5yrs on the control was refering to the original DOP. However, if there is still any of the 5yrs remaining, it would be the balance of the 5yrs or the one year on the replacement part, which ever is greater. If you do have to buy a new control, please do re-verify the 1yr replacement warranty. Manufacturs are in the process of changing their warranties and they are not changing to the benifit of the consumer.

Scott

 

[super32]

relay

The relay should be ok. When the problem was first discovered, bosch said to re-solder the joint. I told them this would not work. Some of my co-workers would re-solder and some of them would fail again quick, and some went on for a year or so. Bosch finally said to replace the control unit if the conection was burnt. After a few years some of the ones that were replaced in 01-03 we are now seeing them fail again. Some havent had any problems at all. Oddly enough this problem was primarily on the units with the controls on the front. The units with top side controls have seen very little trouble.

Hope you didnt order the heater. I have replaced 2 of them in my service years.

Scott

 

[sudsmaster]

Scott,

Dont' worry, this DW was free and so I'm not out any $$, and I'm very hesitant to put any money into it. It is sort of nice to have one I can tear apart without any financial concern (other than a possible junk yard disposal fee).

At least I got this one cleaned up. It was really funky inside. Pretty disgusting. I think they must have left it dirty or something.

I'm puzzled as to why this failure is occuring in the first place. For a relay to burn out its connections, there has to be too much current running through the relay and/or circuitry. If so, wouldn't beefing up the ciruitry or relay resolve the issue, long term? I mean, one could even sister on another conductor (wire) to split the load so the circuit board doesn't overheat. But of course I'm saying this not having seen the actual guts of the thing yet.

 

[sudsmaster]

PS-these flakey control boards must be why Bosch DW's got poor reliabilty ratings in Consumer Reports.

Knock on wood, I'm hoping that my SHU43C doesn't suffer the same fate. It is an awesome machine.

In any case, jeers to Bosch for having produced a machine with a dodgy heater circuit - especially since the biggest selling point of these machines is their in-line heater, able to heat the water to 161F without melting plastic ware on the bottom rack, and using residual heat for condensation drying. Perhaps the circuity was adapted from a lighter gage 220volt design, and inadequately beefed up for the greater amperage that 110volt operation requires.

 

[bingwsguy]

You guys are a wealth of knowledge....I have only been a member for a short time and am learning so much here...I add my 2 cents where I can. Thanks for the continuing education.