Overview
Replacement impeller for the external automatic pump-out (APO) on HydraMaster truckmounts. HydraMaster part number 000-073-011, listed as Impeller, Replacement — for any machine with external APO and, in later manuals, Impeller, Replacement for Posi-Flow and Dura-Flow.
The automatic pump-out empties the recovery tank while you keep working. When its impeller wears, the pump-out slows, then stops keeping up, and the tank fills — usually on the job where you can least afford it.
What it fits
HydraMaster's suggested spares schedule lists this impeller against every machine in the range fitted with an external APO:
- Boxxer 421 and Boxxer 427
- CDS 4.6 and CDS 4.8
- CTS330 and CTS450
- MAXX 450D / 470D
- SpitFire 3.2
It is also listed for the Posi-Flow and Dura-Flow APO assemblies, including on the Boxxer 323HP.
The qualifier that matters is external APO. If your machine has an internal pump-out arrangement, this is not the part.
Why impellers wear
An APO impeller lives in dirty water carrying grit, fibre and hair. It wears from abrasion at the vane tips, and it is damaged by running dry.
The failure is gradual, which is what makes it easy to miss: the pump-out keeps working but moves less each month. By the time an operator notices the tank filling, the impeller is usually well past serviceable. If pump-out has been "getting a bit slow" for a while, the impeller is the first thing to look at.
Fibre wrapped around the impeller hub is the other common finding, and it does not always show as a total blockage — just as reduced flow and a motor working harder than it should.
Maintenance
Inspect the impeller when you service the APO rather than waiting for a symptom. Look for rounded or chipped vane tips, scoring on the faces, and anything wrapped around the hub.
Avoid running the APO dry. It is the fastest way to destroy an impeller and it happens most often when a float switch has failed rather than through operator error — so check the float switch is working while you are in there.
Frequently asked questions
Will it fit my machine?
If your machine has an external APO, HydraMaster list this impeller for it. Confirm your machine has an external pump-out, not an internal arrangement.
Does it fit Posi-Flow and Dura-Flow?
Yes — both are named in HydraMaster's parts lists for this impeller.
Does it come with seals or a housing?
It is listed as the impeller alone. If the shaft seal is weeping, that is a separate part and worth doing at the same time — ask us.
How often should it be replaced?
On condition. HydraMaster treat it as a suggested spare rather than a fixed-interval item. Operators doing heavy restoration work replace them far more often than those doing domestic maintenance cleaning.
Pump-out slowing down? Tell us the machine model and what you are seeing and we will help you work out whether it is the impeller, the float switch or a restriction before you order.
