Our dishwasher (GE PostScrubber 780 – Model GSD 780X 66WW) stopped working a few days ago. It would go through all the motions and emotions as if it was washing, but the dishes would come out dirty. It seems as if something else is breaking every day. But, I should not complain: last time I worked on this dishwasher was in June 1999. 12 years of trouble free operation is not bad at all.
I wanted to see what was happening inside the dishwasher, but as you know as soon as I open the door, the dishwasher would stop operating. I found the key to the door lock such that I was able to operate the dishwasher while the door was open. What I saw was that there was very little water and so the washing arm was not coming up or rotating.
I thought that the problem was with the solenoid that fills the dishwasher with hot water. But when I applied power to the solenoid, it opened up fine and the water was coming in. So I thought the problem must be with the timer. When I called the GE Parts Department, I got a quote for the timer of $103.60 including shipping. But I was not quite sure if the problem was with the timer. I made a trip to Radio Shack and bought a contact cleaner and sprayed the timer to clean out any residue build up. Then I carefully turned the timer knob to see what was happening.
What I saw was that the hot water was coming into the dishwasher, but it was immediately was pumped out of the dishwasher. That was the real problem. Some dishwashers have two impellers, one for washing, and another one for draining. The motor turning one way or the other operates the proper pump. For this to happen the motor would need at least three wires. My dishwasher motor had only two wires, so the motor was always turning in the same direction.
Then I noticed the real problem. There was a solenoid which totally rusted and frozen so it could not move. This solenoid when activated would open the drain valve to drain the water. Since it froze in the drain mode, the pump was never able to wash the dishes. I took out the solenoid and cleaned the core and the inside of the coil so the core can move freely inside the coil.
The first picture above shows the coil in wash mode. It is shiny because I cleaned it. The second picture shows the coil in drain mode, that is the position it got stuck because of the rust.
Normally this solenoid would not rust. When I watched it during operation, I noticed that in the drain mode a little bit of water was leaking from the valve and dripping onto the solenoid and then to the floor. When I checked with the GE parts department, I got a quote of $158.45 for the whole assembly (including shipping). The assembly includes the pump, the motor, and the solenoid. However, since this is a 16 year old dishwasher, I think we are going to buy a new one.
Hot Water Solenoid 1
Hot Water Solenoid 2
By the way, after I replaced the gasket on the drain valve, the water leak has stopped. This gives us a few months to look around for the right dishwasher.