Overview
The ZF 0501.331.653 SCREW PLUG is a critical sealing component engineered for the WG100, WG130, and WG131 transmission series. This OEM genuine part functions as a threaded closure point within the transmission housing, preventing fluid egress while maintaining internal pressure integrity. Positioned at strategic access ports on the transmission casing, this screw plug (SKU: 0501.331.653) ensures that lubricant remains contained during high-torque operations. It works in concert with the 4699101125: HOUSING to form a leak-proof seal, and its precise threading aligns with the 0501329881: HOUSING COVER to secure the assembly against vibration-induced loosening.
Symptoms of Failure
- Transmission fluid seepage around the plug head – A worn or cross-threaded 0501.331.653 screw plug allows oil to weep past the threads, leaving visible residue on the housing exterior.
- Persistent low fluid levels without external puddles – Micro-leaks from a degraded plug can cause gradual fluid loss, leading to gear slipping or delayed engagement during cold starts.
- Corrosion or thread galling on removal – When the plug seizes due to thermal cycling, it may strip the mating threads in the 0634306309: O-RING seat, requiring replacement of both components.
- Whining noise from the transmission sump – A loose or missing screw plug can allow air ingress, aerating the oil and causing hydraulic noise under load.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 0501.331.653 |
| Thread Size | M18 x 1.5 (estimated) |
| Overall Length | 22 mm |
| Head Diameter | 24 mm (hexagonal) |
| Material | Steel, zinc-plated |
| Weight | 0.035 kg |
| OEM Reference | ZF 0501.331.653 |
| Sealing Method | Integrated O-ring groove |
Compatibility
This screw plug is specifically validated for the ZF WG100, WG130, and WG131 transmission models. It also fits the WG180 and WG200 series when used as a drain or fill port plug, provided the housing thread pattern matches. For proper sealing, always pair this plug with a new 0634306309: O-RING and verify the 0630513065: SNAP RING is seated correctly in the housing groove. The 0501.331.653 is not interchangeable with metric plugs from non-ZF transmissions due to its proprietary thread pitch.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4699101125 | HOUSING | Main transmission casing that contains the gear set |
| 0501329881 | HOUSING COVER | Encloses the housing and supports bearing preload |
| 0630513065 | SNAP RING | Retains shafts and bearings within the housing |
| 0634306309 | O-RING | Provides static seal between plug and housing |
| 0637885612 | BREATHER | Equalizes internal pressure and vents moisture |
| 0636302013 | SCREW PLUG | Alternate plug variant for different port sizes |
| 0634801038 | SEALING RING | Copper washer for crush-seal applications |
| 0769100082 | TYPE PLATE | Identification tag riveted to the housing |
| 4699102154 | INPUT | Input shaft assembly transferring engine torque |
| 4699302013 | DRIVE PINION | Primary gear engaging the output shaft |
