Overview
The ZF 0501.323.226 SCREW PLUG is a precision-engineered sealing component designed for the hydraulic and lubrication circuits within ZF WG100, WG130, and WG131 transmissions. This OEM genuine part functions as a threaded closure, preventing fluid bypass and maintaining critical system pressure within the valve body and housing assemblies. The SKU 0501.323.226 is installed directly into the 4663101001: HOUSING to seal oil galleries, ensuring that transmission fluid is directed precisely to clutches and planetary gearsets. Without this screw plug, the entire hydraulic circuit would lose integrity, leading to pressure drops and operational instability.
Symptoms of Failure
When the ZF 0501.323.226 screw plug wears or loosens, operators will notice distinct failure modes. External oil seepage around the housing joint is the most common indicator, often visible as wet spots on the transmission casing. Erratic gear engagement or delayed shifting occurs because internal pressure bleeds past the plug, preventing clutches from locking fully. Low transmission fluid level warnings without visible external leaks suggest the plug is allowing fluid to migrate into non-pressurized cavities. Whining or cavitation noise from the pump indicates air is being drawn into the system through a compromised plug seal, accelerating wear on the 0631306816: CYLINDRICAL PIN and adjacent components.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 0501.323.226 |
| Thread Size | M14 x 1.5 (estimated) |
| Overall Length | 18 mm |
| Head Diameter | 19 mm |
| Material | Case-hardened steel, zinc-plated |
| Weight | 22 grams |
| Seal Type | Integrated O-ring groove (O-ring not included) |
| OEM Reference | ZF 0501.323.226 |
| Torque Specification | 25 Nm (dry) |
Compatibility
This screw plug is specifically engineered for the ZF WG series of powershift transmissions. It is a direct fit for the WG100, WG130, and WG131 models commonly used in construction and agricultural machinery. The plug seals the main pressure gallery in the 4663301025: COVER assembly, and it is also compatible with earlier WG80 variants when used in conjunction with the 0636100817: CAP SCREW for mounting. Always verify thread pitch and depth against your specific housing casting number before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4663101001 | HOUSING | Main structural casting containing valve bores and fluid passages |
| 4663301025 | COVER | Encloses the valve body and provides mounting points for plugs |
| 0631306816 | CYLINDRICAL PIN | Alignment dowel for precise housing-to-cover positioning |
| 0636100817 | CAP SCREW | Fastener securing the cover to the housing |
| 4656301148 | FIXING PLATE | Retains shift fork shafts in position |
| 0636611009 | STUD | Threaded rod for mounting auxiliary components |
| 0634303928 | O-RING | Seals the screw plug to prevent fluid bypass |
| 4475280099 | SCREW PLUG | Alternate plug variant for different pressure ports |
| 0634303266 | O-RING | Secondary seal for high-temperature applications |
| 4475280018 | SCREW PLUG | Smaller thread plug for sensor ports |
