Bosch Dishwasher Repair SHU43C SHU43C05

Hints, pictures and video for replacement of a pump seal and impeller for a Bosch dishwasher. No service manual or repair instructions appear to be on the 'net for download, so I thought I'd try to help out...

The Cliff's Notes version of this project: the dishwasher had become very loud when washing, with a significant squeal factor. I ordered an impeller kit (see below) for the pump from PartsTap.com (thanks!) and installed it, which solved the problem. Removal & rebuilding of the pump requires pulling the dishwasher out from under the cabinet, turning it upside down, fixing the pump, and then reinstalling. It probably took me 3 1/2 hours, but I didn't know what I was doing and made a few missteps, taking apart stuff that didn't need to be.

The impeller kit order, from PartsTap.com you can email them at: customerservice **at** partstap.com
I received the shipment 3 or 4 days after ordering it.

Part Number Description Qty Price
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PT8407128 (167085) Circulation pump repair kit 1 $67.48
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Subtotal $67.48
Tax $0.00
Shipping $5.95
Total $73.43
Now, details:

A voltage tic - available at Home Depot, etc. Place it next to a wire and it will tell you if the wire is live or not. Important to make sure you've shut off the correct circuit breaker. Also shown is a T20 Torx driver, available at Home Depot, Sears, etc.

This is looking at the base of the dishwasher after the kick plate has been removed. You may need to raise the feet (front two and one in rear) in order to get the dishwasher out from under the countertop. The round thing in the middle is the head of the adjustment shaft that raises & lowers the rear foot.

Here is the dishwasher pulled out. Don't forget to disconnect the drain tube from the kitchen sink.

This picture shows the relative positions of the wires on the small pump (the "macerator"?) (not the one being repaired), so that once I remove them I can get them back on in the proper positions. I had to remove some wiring and tubing to be able to lift the bottom off of the rest of the dishwasher (after I removed it and turned it over).

A digital camera is a great help for ensuring that you know how it all goes back together!

A ground wire.

Another ground wire.

Yet another ground wire.

This shows the clips on the side of the connectors. In order to remove the bottom of the dishwasher, several wires and hoses needed to be disconnected. In the case of these wires, however, simply unsnapping the connector blocks from the bottom of the dishwasher allowed enough leeway to get the bottom off. The connectors snap into the bottom - use a small flat blade screwdriver to push in the clips and release the connectors.

The three pillars in the center of this picture are where the connectors described above snap in.

Also note in this picture, towards the left-hand side, the debris left by the leaking pump. The pillar next to that debris is where one of the rubber motor mounts hooks on - more about that below.

This video shows the suspension mounting points for the motor mounts. The dishwasher is still upside down at this point, and this is before the bottom was removed.

This picture shows the dishwasher with the bottom removed. Note that it's not entirely disconnected - there is no need to unhook everything.

This picture shows the two rubber motor mounts for the pump motor. They work by suspending the motor, so when the dishwasher is upside down they have a tendency to come off the mounting pillars - watch this carefully after the dishwasher has been reassembled and turned back upright.

The screwdriver is pointed at a small catch or prong that must be depressed in order to rotate the pump motor with respect to the pump head, in order to separate the two. It should rotate easily. After rotating it, you may have to pull on it with a fair amount of force in order to free the o-ring seal. Careful not to rip out anything when doing this - hold the pump head firmly in place and pull on the motor.

This video shows rotating the pump motor in order to separate it from the pump head. Also, you can see that it does not want to come completely free, despite being wiggled. In the end, I had to put the camera down and hold the pump head (white plastic) so as to prevent the rubber inlet and outlet connections from being pulled too hard.

Note that nothing on the inside of the dishwasher needs to be removed for this procedure. I figured that out only after completely removing the whole pump assembly from the bottom of the wash tub.

In this video, you can see that I have removed the whole pump assembly from the bottom of the wash tub - don't do that, it's not necessary. Also in the picture you can see that the pump impeller and backing plate have not yet been removed from the pump motor.

I don't have any images or video of the pump seal being removed from the backing plate. Be careful with that procedure - work the old pump seal out of the backing plate by gently pushing it out from the motor side using a small screwdriver or similar. Work you way around and around to ease it out - don't try to do it all at once.

When installing the new seal, I cleaned the backing plate thoroughly then used a very small amount of Pam on the surface of the backing plate where the seal slides in. Always, be very careful not to damage the smooth carbon face of the seal, and keep it clean (no lubricant, grit, etc.).

This video shows the pump after the impeller has been removed. You can see the old seal still in place in the backing plate, and the o-ring around the perimeter of the backing plate. Also, you can see that the backing plate has non-equal lugs or ears, so that it only mates to the pump motor in one way.

This is the pump motor after the motor has been separated from the pump head and the impeller and backing plate (white plastic) have been removed. The impeller threads onto the shaft with normal, right-hand threads. Prevent the pump shaft from turning by blocking a fan blade at the opposite end and then unscrew the impeller. It should come right off. Then remove the backing plate.

In this picture, there is still a seal 0r guide remaining on the motor shaft - that slides right off. A replacement was included in my impeller kit.

This video shows the orientation of the small seal or guide that is the last part to come off and the first part to go back on to the pump motor shaft. The seal has one wider side and one narrower side, so pay attention when putting it back on.

I realized after I had been working at this for a while that there is a tube that isn't connected to anything. This is a vent that leads to a side of the dishwasher tub.

I wanted to lubricate the o-ring a bit before reassembling the pump head, but you need to be careful not to use an incompatible lubricant. Since I didn't know the material used for the o-ring, and since almost all o-ring materials tolerate vegetable oils well, I used a small amount of Pam on the o-ring.

Note that the impeller-to-seal interface should not be lubricated. The seal is a carbon seal that runs on a matching face of the impeller (a ceramic face?).

This video shows how the door counterweight springs get hooked back up to the strings. Note that the spring was not seated at the back of the dishwasher so that I could do this with one hand while filming it.