Scooba 450 broken pump fixed

[Mike]

#838

So my Scooba 450 died with the pump not working. Pulled it apart and sure enough the pump seals were not only ripped, they were bad. Apparently this was a really crappy design and has ended the life of many Scoobas.

After staring at it for awhile, I realized it “Ain’t gonna lick itself” and decided it was time to repair it once and for all.

So, I did. The way they have the pump set up is that the hose that the pump works on is not really good. It tends to go flat and stick together which pretty much kills the priming function. This would be an easy fix with a new 1/4 hose, but the bigger problem is they used an absolutely crappy sealing system to connect the pump to the scooba pipes. It’s junky silicone, it leaks, and worst of all it rips apart when you try to remove the pump. Then you’re dead.

Solution is this: Pull the plumbing on the pump, put a new longer 1/4 food grade line in, and route the line right to the scooba’s plumbing. It doesn’t quite fit, but a little force can make wonders work….

Some pictures (note: this forum doesn’t display high detail images well. Posting the links).

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The space you have to work with is minimal but there

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Putting in and plumbing the pump. Yaay, it fits without kinks.

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Well, sort of. Have to put the blower exhaust stack back in….

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Looks like it’s routed well enough. Now to see if it works tomorrow once I charge up the battery…..

[Jonathan]

#1064

Silicone as in industrial grade RTV silicone or as in household grade silicone sealant (which is mostly acrylic, with a small amount of silicone)?

The household acrylic/silicone sealant is intended for bathtubs, where nothing moves.

The industrial RTV silicone is pure silicone and can take a serious beating without failure.
But you won’t find it in hardware stores!

[Mike]

#1065

Commercial grade RTV Silicone sealant. The pump is not supposed to move on the pipes, but that’s moot now. Another problem is the pickup tubes for the pump are right next to the gasket so if you get even a molecule across those inlets then the pump won’t work right.

So far mixed bag. On the good side the pump is putting down water when I press clean. So the pump is working. However it still flunks with “Tank is empty” message after running the pump for a bit (and putting down water/scooba cleaner).

So time to troubleshoot that. Does anyone know:
1) What the values should be from the tank in order for the Scooba to think the tank has water (not sure if this is the problem, as when I fill the dirty tank it does detect that before doing anything).
2) Is the scooba looking for water using a PH sensor in the water stream or is it looking for changes in light (using a LED/photodiode).
3) Should I put vinegar in the tank (been using scooba juice, the white bottle)
4) Can I just bypass the water sensor by cutting and shorting those sensor wires coming out of the potted thing in line with the water pipes just downstream of the pump?

Closer, but not there yet.

[Jonathan]

#1066

Well, tried 2 capfuls of vinegar, still no dice. Took it apart, cut the wires to the sensor, stripped and twisted them together, back on the floor and now it’s working! And it is putting down *plenty* of water, will be interesting to see how much is put down and sucked up.

I suppose I could plumb in a 5800 water sensor if I really want/need to, but so far so good….

[Mike]

#1067

Works like a dream. On a full kitchen run it emptied 90% of the water in the tank and the dirty tank was over 50% full. I’ll measure it, but this is easily twice as much liquid as it has ever put down before. Note this is a non-upgraded 450 as the upgrade is no longer possible to install.

I’d say “works as factory new” at this point. So plumbing in a new line and going around those stupid gaskets is the way to get your 450 back to peak performance!

[Author]

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