Overview
The ZF 4166.339.281 PUMP WHEEL is a critical hydraulic component engineered for the WG65 series of powershift transmissions. As the primary driver of the torque converter’s pump circuit, this OEM genuine part generates the oil flow necessary for clutch engagement and transmission cooling. The SKU 4166.339.281 sits directly on the converter hub, rotating at engine speed to pressurize the transmission’s internal hydraulic system. Without this pump wheel, the WG65 cannot build line pressure, making the vehicle immobile. This part is precision-balanced to minimize vibration and ensure consistent fluid delivery across all operating ranges.
Symptoms of Failure
When the 4166.339.281 pump wheel begins to fail, operators often notice delayed engagement when shifting from neutral to drive, a classic sign of insufficient hydraulic pressure. Another common symptom is intermittent gear slipping under load, particularly when climbing grades or hauling heavy payloads. You may also detect erratic torque converter lockup accompanied by a whining noise from the bell housing. Finally, chronic low transmission fluid pressure on the gauge, despite proper fluid levels, frequently points to a worn or damaged pump wheel that can no longer maintain adequate flow.
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number | 4166.339.281 |
| Material | High-strength aluminum alloy (die-cast) |
| Outer Diameter | 165 mm (approx.) |
| Hub Bore | 28 mm (approx.) |
| Weight | 1.2 kg (2.65 lbs) |
| OEM Reference | ZF 4166.339.281 |
| Surface Finish | Anodized for corrosion resistance |
Compatibility
This pump wheel is specifically designed for the ZF WG65 series transmission. It is also compatible with the WG180, WG200, and WG250 models that share the same torque converter pump assembly. The part fits both standard and heavy-duty variants of these transmissions used in construction, agricultural, and material handling equipment. Always verify the pump wheel’s vane profile against your existing unit, as minor revisions exist between early and late production runs.
Related Components
During installation, the pump wheel works in concert with several adjacent parts. The 4616105402 OUTPUT shaft transfers torque from the converter to the gearset, while the 4005303005 OUTPUT FLANGE connects to the driveline. The entire assembly is housed within the 4616101119 TRANSMISSION HOUSING, secured by 0636011038 HEXAGON SCREW fasteners. For a complete rebuild, consider the following supporting hardware:
| Part Number | Name | Function |
|---|---|---|
| 0636011118 | Hexagon Screw | Secures pump wheel hub to converter |
| 0636016015 | Hexagon Screw | Mounts pump cover assembly |
| 0631306085 | Cylindrical Pin | Aligns pump wheel to drive hub |
| 0634313118 | O-Ring | Seals pump wheel bore to prevent leakage |
| 0636304019 | Screw Plug | Closes hydraulic test port on housing |
| 0634801152 | Sealing Ring | Prevents oil seepage at pump outlet |
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