The Wacker Neuson 5100040903 is a genuine OEM O-Ring designed for the APT4S and APT4T series self-priming trash pumps. As a factory-sourced component, it meets the exact material and dimensional standards specified for these machines, ensuring a proper seal every time. This O-Ring is confirmed to fit multiple APT4S and APT4T configurations, including cold weather variants, surge brake, and electric brake models. When your pump shows signs of leaking or you are performing a routine service, replacing the 5100040903 with a genuine Wacker Neuson part keeps the system sealed and operating as intended.
Key Features
- Genuine OEM Sealing Material — Sourced directly from Wacker Neuson, this O-Ring is manufactured to the exact compound hardness and compression specifications required for fluid-tight performance in the APT pump series.
- Drop-In Replacement — Dimensionally matched to the original, this O-Ring seats into its groove without trimming, stretching, or adapting — critical for maintaining consistent compression across the sealing surface.
- Broad APT4 Series Coverage — Fits APT4S Pump with Skid, APT4T Pump with Surge Brake, and APT4T Pump with Electric Brake, including all available Cold Weather variants, covering six machine configurations.
- Leak Prevention — A failed or worn O-Ring in a trash pump allows fluid to bypass the sealed junction, causing pressure loss and potential contamination of surrounding components. A fresh 5100040903 restores the integrity of that seal.
- Fluid System Integrity — Sealing components in pump assemblies are critical to safe and contained fluid handling. Using the correct OEM O-Ring ensures the pump operates within its designed pressure and containment parameters.
An O-Ring creates a mechanical seal between two mating surfaces, preventing fluid or air from escaping at a joint or connection point within the pump assembly. In a self-priming trash pump like the APT4S and APT4T, O-Rings are used at key junctions where maintaining a pressurized, leak-free path is essential to efficient pumping performance. When an O-Ring ages, hardens, or becomes damaged, the seal degrades — leading to visible leaks, reduced suction, or a complete loss of prime — making timely replacement a straightforward and essential part of routine pump maintenance.
Part Details
| Part Number | 5100040903 |
|---|---|
| Brand | Wacker Neuson |
| Part Type | Genuine OEM |
| Description | O-Ring |
Compatibility & Fitment
| Name | Model | Machine Number |
|---|---|---|
| APT4S Pump w/Skid, Cold Weather | APT4S CW | 5200019798 |
| APT4T Pump, Electric Brake, Cold Weather | APT4T CW | 5200019793, 5200019792 |
| APT4T Pump, Surge Brake | APT4T | 5200019643, 5200019644 |
| APT4S Pump w/Skid | APT4S | 5200018977 |
Verify Before You Order
Fitment is machine-number and revision-specific; always confirm your model and serial number against the fitment list.
Why Buy From DHS Equipment
Every part is verified against the manufacturer's part number before it ships, so what you order is what arrives. We carry parts from leading OEM brands and our own DHS Quality Parts line of professional aftermarket components. Need help finding the right part? Our team is available to confirm compatibility whenever you need it. Orders are processed fast to keep your jobs on track. We don't just sell parts. We keep you jobsite ready.
Questions? Contact our team at [email protected] or 866-611-9369 — DHS Equipment is here to help you maintain peak performance.
