The Wacker Neuson 5200021685 is a genuine OEM O-Ring designed for the APT4S and APT4T series self-priming pumps. As a factory-sourced component, it is manufactured to the exact material and dimensional specifications required for proper sealing within the pump assembly. This O-Ring fits across multiple APT4 configurations, including standard, electric brake, surge brake, and cold weather variants, covering both the APT4S Pump with Skid and the APT4T Pump lineup. Verifying your model number against the fitment list before ordering ensures a direct, hassle-free installation.
Key Features
- Exact Material and Dimensional Spec: — Sourced directly from Wacker Neuson, this O-Ring meets the precise compound hardness and cross-section diameter required to form a reliable seal in the APT4 pump system.
- Drop-In Installation: — Engineered to seat correctly in the existing groove without trimming or adjustment, making replacement straightforward during routine service or after a seal failure.
- Broad APT4 Series Coverage: — Compatible with APT4S Pump with Skid, APT4T Pump with Electric Brake, APT4T Pump with Surge Brake, and all corresponding Cold Weather variants.
- Maintains Pump Integrity: — A sound O-Ring prevents fluid bypass and pressure loss at critical pump joints, allowing the APT4 to sustain proper suction and discharge performance during operation.
- Fluid System Safety: — A degraded or missing O-Ring can allow pressurized fluid to escape at sealing interfaces, creating a hazard on the worksite and accelerating wear on adjacent pump components.
An O-Ring is a circular elastomeric seal that sits within a machined groove at a joint or connection point inside the pump assembly. Its role is to prevent fluid or air from bypassing that interface under pressure, keeping the pump's suction and discharge circuit fully sealed. When an O-Ring hardens, cracks, or becomes compressed beyond its service limit, the seal degrades, causing pressure drop, fluid leakage, or loss of prime — all of which reduce pump output and can lead to more extensive damage if left unaddressed.
Part Details
| Part Number | 5200021685 |
|---|---|
| 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.
