Overview
The ZF 4651.120.001 PRESSURE REGULATOR is a critical hydraulic control component engineered for the WG 100 Series transmission family. This OEM genuine part precisely modulates oil pressure within the valve body assembly, ensuring consistent clutch engagement and smooth gear shifts. As a direct-fit replacement, the SKU 4651.120.001 maintains factory-specified flow rates and pressure thresholds, preventing erratic transmission behavior. It interfaces directly with the 4651101007: TRANSMISSION HOUSING and the 4651301029: HOUSING, forming a sealed hydraulic circuit that governs torque converter lockup and planetary gear operation.
Symptoms of Failure
- Erratic shift timing and gear slipping: A worn pressure regulator causes inconsistent hydraulic pressure, leading to delayed upshifts or unexpected downshifts under load.
- Oil leaks around the valve body area: Degraded sealing surfaces allow ATF to escape, often pooling near the 0634303928: O-RING interface or the 4651301024: HOUSING.
- Harsh engagement from neutral to drive: Failed pressure regulation results in sudden clutch pack application, creating jarring starts and increased driveline stress.
- Transmission overheating and burnt fluid smell: Uncontrolled pressure spikes generate excessive friction, raising operating temperatures and accelerating fluid degradation.
Technical Specifications
| Parameter | Value |
|---|---|
| OEM Part Number | 4651.120.001 |
| Material | Hardened steel with corrosion-resistant coating |
| Weight | 0.45 kg (1.0 lb) |
| Dimensions (L x W x H) | 85 mm x 40 mm x 30 mm |
| Pressure Range | 8–22 bar (116–319 psi) |
| OEM Reference | ZF 4651.120.001 |
| Seal Type | Integrated O-ring groove (uses 0634303928: O-RING) |
Compatibility
This pressure regulator is primarily designed for the ZF WG100 series, including models WG100, WG120, and WG150. It also retrofits into WG180 and WG200 transmissions when paired with the correct 4651301024: HOUSING adapter. Always verify your transmission serial number before ordering. For WG200 applications, ensure the 4651101007: TRANSMISSION HOUSING is free of scoring to prevent premature regulator wear.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4651101007 | TRANSMISSION HOUSING | Main structural casing for gear train and valve body |
| 4651301029 | HOUSING | Secondary housing for clutch pack assembly |
| 0634303928 | O-RING | Seals pressure regulator to valve body bore |
| 4651301024 | HOUSING | Adapter housing for WG180/WG200 compatibility |
| 4651203002 | SCREEN SHEET | Filters debris from hydraulic fluid before regulator |
| 4651303005 | SCREEN SHEET | Secondary filtration for high-pressure circuits |
| 0636101032 | CAP SCREW | Secures regulator assembly to housing |
| 0630361028 | SEALING CAP | Prevents fluid loss from unused ports |
| 4475280060 | SCREW PLUG | Threaded plug for pressure test points |
| 0634303312 | O-RING | Seals screw plug and sealing cap interfaces |
