Black water tank macerator pump problem - Impeller swollen?

[Momac]

I have a macerator pump to discharge the toilet holding tank to the water (where legally permitted)
For a few occasions when pumping out the pump has been cutting out before the tank is empty due to overheating. This fault has deteriorated to the pump motor failing to turn when power is applied.
All looks clean inside the pump.
The electric motor turns okay under electrical power with the pump body removed.

Can the holding tank effluent cause the impeller to swell up and cause extra resistance sufficient to stop the motor from turning?

 

[jon and michie]

Could be a blockage in the impeller other than human waste or is the impeller damaged causing the motor to stop turning and cutting out ?

 

[Momac]

Could be a blockage in the impeller other than human waste or is the impeller damaged causing the motor to stop turning and cutting out ?

There is no blockage and the existing impeller looks fine.
I have a spare impeller and will try that

 

[jon and michie]

maybe youtube your make.
I have done this previously on my Dometic and fixed it

 

[sc25 Sweden]

When the seals on the pump axle and the impeller wear the macerator looses its ability to self prime. The pump then overheats and the inbuilt thermal cut out turns off the motor. I had this problem on my sc29 as the macerator was mounted at the limit of the stated ”head” that the pump can self prime and a slight reduction in performance causes the ”run dry” problem. I changed the impeller type macerator to a Jonsson diaphragm type that has a better ”head” and can run dry.

 

[BruceK]

I have had a similar problem in the past where hair was the culprit. Turned out the daughter was showering and then dispensing the collected hair from the shower drain and disposing it down the toilet. This over time created a hairball upstream of the pump that although would allow water through it was insufficient to keep the pump flooded and would cause it to trip out after a few minutes, Unfortunately after clearing that out remnants then later wound round the motor shaft causing and instant trip. I got my own back by making her stand in the engine bay and pass me the tools as needed while I attempted repairs. The sounds of her dry retching for the 15 minutes it took to remove pipe and shop vac the effluent up had me in stitches and I have never had a problem since. So, look for partial blockages upstream of the pump as well.

 

[Momac]

I changed the impeller with no benefit . With the pump assembled on the motor the motor will not turn the shaft as it there is not enough power in the motor.
I would open up the motor but can't locate a socket to fit the hex screws (which sit in a recess). A spanner will not fit.

 

[sc25 Sweden]

New pump time

 

[Momac]

I think so

 

[BruceK]

some pumps have a screwdriver slot on the rear motor end of the shaft to help kickstart them if your motor doesnt start up (brush issues or blockage) or at least my previous one did. Attack a screwdriver bit to a cordless drill and crank away. If nothing else it was helpful in emptying the tank when the pump needed to be replaced.

 

[BruceK]

Attatch sp. Not attack. Brain farted. sry

 

[Portofino]

Commutator is dirty .Disassembly + clean up might eek out a few more yrs