Overview
The ZF 7647.955.123 ROTOR PUMP is a critical hydraulic component engineered specifically for the WG 65 Series transmission family. This OEM genuine part serves as the primary fluid mover within the transmission’s lubrication and control circuit, ensuring consistent oil pressure for clutch engagement and gear cooling. The SKU 7647.955.123 sits directly within the pump housing assembly, drawing transmission fluid from the sump and delivering it under pressure to the valve body and torque converter. When installed correctly with a properly sealed TRANSMISSION HOUSING, this rotor pump maintains the precise hydraulic balance required for smooth shifting under heavy loads.
Symptoms of Failure
When the ZF 7647.955.123 rotor pump begins to wear, operators often notice a gradual loss of hydraulic pressure, leading to delayed gear engagement or harsh shifting. A common long-tail search query is “ZF WG65 transmission slipping under load,” which frequently traces back to a worn rotor pump unable to maintain adequate flow. Another failure symptom includes intermittent oil starvation, causing whining noises from the transmission during acceleration. You may also observe external seepage around the pump mounting area if the sealing surfaces are compromised, often accompanied by a drop in fluid level on the dipstick. If these issues are ignored, complete pump seizure can occur, requiring replacement of both the rotor pump and the HEXAGON SCREW fasteners that secure the assembly.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 7647.955.123 |
| OEM Reference | ZF 7647.955.123 |
| Material | Hardened steel rotor with aluminum housing |
| Weight | 1.85 kg (4.08 lbs) |
| Overall Diameter | 92 mm |
| Height | 48 mm |
| Operating Pressure | 8-12 bar (116-174 psi) |
| Flow Rate | 18 L/min at 2000 RPM |
| Seal Type | Integrated O-ring groove |
Compatibility
This rotor pump is primarily designed for the ZF WG 65 Series, including models such as the WG65, WG80, WG120, WG150, WG180, and WG200 transmissions. It is also compatible with certain variants of the ZF Ecomat series that share the same hydraulic architecture. For proper installation, always pair this pump with the correct HEXAGON SCREW and HEXAGON SCREW fasteners to achieve the specified torque values. Verify your transmission model’s serial number before ordering, as minor design changes occurred after 2015 production runs.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4616101059 | TRANSMISSION HOUSING | Encloses and supports the rotor pump assembly |
| 0636011038 | HEXAGON SCREW | Secures pump mounting bracket |
| 0636011118 | HEXAGON SCREW | Fastens pump cover plate |
| 0636016015 | HEXAGON SCREW | Attaches pump to transmission housing |
| 0631306085 | CYLINDRICAL PIN | Aligns pump rotor during assembly |
| 0634313118 | O-RING | Seals pump outlet port |
| 0636304019 | SCREW PLUG | Closes pressure test port |
| 0634801152 | SEALING RING | Prevents fluid leakage at plug |
| 0732611049 | FILTER INSERT | Captures debris before pump inlet |
| 0634303718 | O-RING | Seals pump inlet connection |
