SS870 Waste Tank Upper Float Switch Adjustment? | TruckMount Forums #1 Carpet Cleaning Forums

SS870 Waste Tank Upper Float Switch Adjustment?

MSI

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Tom Andrews
SS870 upper float switch in waste tank appears to be intermittent. Symptom: engine runs smoothly, hesitates for a second or two (engine dies), then resumes immediately at full RPM while tools are operating. Anyone know how to clean/maintain &/or adjust the float switch? Its a Harwil L-21N. A couple years ago a great mechanic at Hi-Press in Tulsa adjusted same switch in my brother's SS870 but I'm 900 miles from Tulsa with no Sapphire TM tech close. It's a magnetically actuated cherry switch in a waterproof housing, very cool engineering. Just can't figure out what he did.
 

Ara Klujian

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SS870 upper float switch in waste tank appears to be intermittent. Symptom: engine runs smoothly, hesitates for a second or two (engine dies), then resumes immediately at full RPM while tools are operating. Anyone know how to clean/maintain &/or adjust the float switch? Its a Harwil L-21N. A couple years ago a great mechanic at Hi-Press in Tulsa adjusted same switch in my brother's SS870 but I'm 900 miles from Tulsa with no Sapphire TM tech close. It's a magnetically actuated cherry switch in a waterproof housing, very cool engineering. Just can't figure out what he did.
I am very familiar with this switch. There is a way to inspect the electrical wiring without removing the float from the tank. I need more information from you before I can lead you in the right direction. Is the tank full when it cuts out? Does the engine resume when it should be off?
 

MSI

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Tank is at various levels when this happens. I already re-connected plug/jacks in harness. When I took my bro’s 870 to shop in Tulsa, they removed, disassembled, adjusted, & reinstalled switch. It’s worked flawlessly since. Makes me think the cherry switch is marginally adjusted inside housing now. The switch assembly is expensive, I’ve already replaced it some time ago for similar condition, & would rather adjust if you know how. When tank is full & I’ve forgotten to turn waste pump on, it shuts down hard with no restart until level goes down.
 

Ara Klujian

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Tank is at various levels when this happens. I already re-connected plug/jacks in harness. When I took my bro’s 870 to shop in Tulsa, they removed, disassembled, adjusted, & reinstalled switch. It’s worked flawlessly since. Makes me think the cherry switch is marginally adjusted inside housing now. The switch assembly is expensive, I’ve already replaced it some time ago for similar condition, & would rather adjust if you know how. When tank is full & I’ve forgotten to turn waste pump on, it shuts down hard with no restart until level goes down.
Sorry for the late reply. There is no adjustment on the cherry switch. The only thing I can think of is maybe a screw was loose in your bros switch. Other than that it's pretty basic. Usually the switch lever does need to fall back down in order to restart the engine.
 

Ara Klujian

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One thing I recommend anyone doing when u take that switch apart is spray a little wd40 on the wiring harness right on the rubber stopper. Get the w d4 0 in there good, then gently wobble and twist it out WHILE holding the wiring harness so it doesn't pull on the terminals.
 

Ryanj

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I will bag to differ, if it’s the gray 1” 1/4 float switch that’s common to find in most truck mounts. The four screws can be removed and there is a little black switch inside. With a small flat head screw driver you can loosen the the black micro switch and adjust the sensitivity of the switch. Retighten the flat head screw and resemble the switch. This is more then likely what they have done
 

ACP

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honestly sounds like sapphire over engineered a float switch.

regular old septic tank float switches can easily last 25-30yrs, rarely if ever fail and are easily working 20x harder than a truckmount waste tank float. Plus if they dont trigger its a much bigger problem then a blower getting flooded lol

I dont see why you would not just use a regular old float switch thats super easy to adjust, repair, replace

kinda funny
 
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Ryanj

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The problem with using septic tank floats is because of the temperature rating and the forces the floats are put under. Vaccum loads these units do an when the unit bypass water talking 250f plus of super heated water. Most. Basic floats can’t with stand high heat and vacuum stress. Why you commonly see these gray new style floats in the truckmounts.
 

ACP

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By the time your water hits the waste tank its no where near 250.

The vacuum its under is heavy but many many truckmounts use pretty basic float switches.
I wasnt saying use a septic float necessarily, I was just comparing how durable they are and the function of a float switch is really basic so it should be really easy to adjust it.
 

Ryanj

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Different models will bypass water at dredge the temps. Cat valves 165-185f from the water box or temperature set points of older prochem models. Ones with the temp controller. Those can dump water from the pressure side when the unit is at its max temp to cool it’s self. The float switch is normally positioned the next baffle over from the dump fitting in the tank so it’s not in direct contact.
Also consider when the tank fills water the temperature of the water in the tank.
I know it’s common with the new style floats the swivel of the arm will wear out and the float has to be changed out.
Most manafactures now use the new style floats for there own resions.