The Wacker Neuson 5200021691 is a genuine OEM O-Ring designed for the APT4S and APT4T series self-priming pumps. This includes standard configurations, electric brake and surge brake variants, and cold weather models across both the APT4S and APT4T families. As a direct factory replacement, the 5200021691 meets the original dimensional and material specifications required to maintain a proper fluid seal within the pump assembly. Confirm your model number before ordering to ensure this O-Ring is the correct fit for your specific pump configuration.
Key Features
- Correct Sealing Geometry — Manufactured to the exact cross-section and durometer rating required for the APT4S and APT4T pump assemblies, ensuring a proper compression seal without deformation over time.
- Genuine OEM Part — Sourced directly from Wacker Neuson, this O-Ring carries the same material grade and dimensional tolerances as the original component installed at the factory.
- Broad APT-Series Coverage — Fits APT4S Pump with Skid, APT4T Pump with Surge Brake, APT4T Pump with Electric Brake, and all corresponding cold weather variants.
- Leak Prevention — A correctly seated O-Ring maintains internal pressure and prevents fluid bypass at critical joints; a worn or damaged O-Ring leads to seal failure, pressure loss, and potential pump damage.
- Drop-In Replacement — Matches the original seating groove dimensions in the pump housing, allowing straightforward installation during routine service or pump rebuild.
An O-Ring is a precision-molded loop seal used at joints, ports, and connections within the pump to prevent fluid or air from escaping under pressure. In a self-priming pump like the APT4S and APT4T, maintaining a reliable seal is critical to sustaining prime and delivering consistent flow — a failed or degraded O-Ring allows air ingress or fluid leakage that can cause the pump to lose prime, cavitate, or perform erratically. Replacing a worn O-Ring at the first sign of leakage is one of the simplest and most cost-effective ways to restore full pump performance.
Part Details
| Part Number | 5200021691 |
|---|---|
| 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.
