ZF 4657.354.025 PUMP FLANGE for WG171/WG190/WG191 | OEM Genuine Part

Overview

The ZF 4657.354.025 PUMP FLANGE is a precision-machined OEM genuine component designed to secure and align the hydraulic pump assembly within ZF WG-series transmissions. This part number 4657.354.025 serves as the critical interface between the pump drive and the transmission housing, ensuring proper oil flow and pressure regulation for smooth gear engagement. Located at the rear of the pump section, this flange directly mounts to the TRANSMISSION HOUSING and works in conjunction with the HOUS.FRONT SECT to create a sealed, high-pressure chamber. Without a properly functioning pump flange, the transmission cannot maintain adequate hydraulic pressure, leading to performance degradation.

Symptoms of Failure

• External oil seepage at pump mounting point: When the flange face warps or the sealing surface corrodes, you will notice oil dripping from the bell housing area. This is a common “ZF transmission pump flange leak” symptom that requires immediate attention.
• Erratic shifting or delayed engagement: A worn flange allows pump misalignment, causing pressure fluctuations. Operators often report “transmission slipping in forward gears” or “hard shifting when cold” as the pump struggles to maintain consistent flow.
• Metallic debris in transmission fluid: As the flange wears against the pump housing, fine metal particles contaminate the oil. This often triggers “transmission filter clogging” warnings and requires replacing the SCREEN SHEET simultaneously.
• Whining noise from pump area: A loose or cracked flange creates air ingestion, producing a high-pitched whine that increases with engine RPM. This “ZF transmission pump noise” is a clear indicator of flange failure.

Technical Specifications

Compatibility

This pump flange is engineered for ZF WG-series transmissions, specifically the WG171, WG190, WG191, and WG210 models. It is also compatible with the WG180 and WG200 series when used with the appropriate O-RING and CAP SCREW kit. For installations requiring the HOUSING REAR PART, verify the flange orientation matches the pump drive spline count. Always pair this flange with the CYLINDRICAL PIN for precise alignment during reassembly.

Related Components

Frequently Asked Questions

Q: Can I reuse the old O-ring when installing a new pump flange?
A: No. Always replace the sealing O-ring (part 0634313514) with a new one. The flange’s sealing surface is machined to a specific tolerance, and a compressed O-ring will not provide a reliable seal, leading to immediate oil leaks.

Q: Does this flange fit the WG210 transmission without modification?
A: Yes, the 4657.354.025 is directly compatible with WG210 models. However, verify that your pump drive shaft uses the same spline count (typically 14-tooth). If you have a 12-tooth pump, you will need the corresponding flange variant.

Q: What torque specification should I use for the mounting bolts?
A: Tighten the six M10 cap screws (0636100803) to 45 Nm in a cross-pattern sequence. Over-torquing can warp the flange and cause premature failure. Always use a torque wrench for this critical assembly step.