Overview
The ZF 0631.405.057 PLUG is a precision-engineered sealing component designed for the WG260 transmission series and its compatible variants. This OEM genuine part serves as a critical closure element within the transmission housing assembly, preventing fluid loss and maintaining internal pressure integrity. Positioned at designated access points in the gearbox casing, the plug ensures that hydraulic circuits remain sealed during operation. The SKU 0631.405.057 is manufactured to ZF’s exacting tolerances, guaranteeing a secure fit that withstands high-temperature transmission fluid exposure. When installed alongside a robust TRANSMISSION HOUSING, this plug forms an essential barrier against contamination ingress.
Symptoms of Failure
- Transmission fluid seepage around the plug bore: A worn or improperly seated 0631.405.057 plug often results in slow oil drips accumulating near the housing exterior, visible during routine undercarriage inspections.
- Hydraulic pressure drop during gear engagement: When this plug loses its sealing capability, internal pressure fluctuations may cause delayed shifting or erratic clutch pack behavior, particularly in WG260 models.
- Contaminated fluid due to external debris entry: A compromised plug allows dirt and moisture to enter the transmission, leading to accelerated wear on internal components like the HOUSING assembly.
- Audible hissing or whistling from the transmission case: Air escaping past a degraded plug creates a distinct noise under load, signaling immediate replacement needs.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number | 0631.405.057 |
| Material | Steel with zinc-plated finish |
| Thread Size | M18 x 1.5 |
| Overall Length | 22 mm |
| Hex Head Size | 17 mm |
| Weight | 0.04 kg |
| OEM Reference | ZF 0631.405.057 |
| Sealing Type | Metal-to-metal with O-ring groove |
Compatibility
This plug is engineered for direct fitment across multiple ZF transmission families. It is primarily specified for the WG 258 Series, WG 260 Series, WG 261 Series, WG 308 Series, and WG 311 Series. Additionally, it serves as a replacement part in earlier WG180 and WG200 models where the same thread pitch and sealing interface are used. Always verify the plug’s compatibility with your specific transmission housing by cross-referencing the part number against your unit’s assembly diagram. For secure installation, pair this plug with a HEXAGON SCREW or a CAP SCREW when mounting adjacent covers.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4646101156 | TRANSMISSION HOUSING | Main casing that encloses gear sets and hydraulic components |
| 4646301327 | HOUSING | Secondary housing section for valve body or clutch pack |
| 0636015304 | HEXAGON SCREW | Fastener for securing housing flanges |
| 0636101828 | CAP SCREW | Threaded fastener for cover plate attachment |
| 4646301102 | COVER SHEET | Protective plate for access openings |
| 4646301285 | COVER SHEET | Alternate cover sheet for different housing variants |
| 0730365190 | TYPE PLATE | Identification label for transmission model |
| 0631311009 | GROOVED STUD | Alignment pin for housing assembly |
| 0636101193 | CAP SCREW | Fastener for valve body retention |
| 0636010179 | HEXAGON SCREW | Bolt for oil pan or filter cover |
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