Overview
The ZF 4644.121.239 OIL PIPE is a precision-engineered fluid conduit designed specifically for the lubrication and cooling circuits within ZF WG180 and WG200 series transmissions. This OEM genuine part ensures that hydraulic oil is delivered under controlled pressure to critical bearing surfaces and gear meshes, preventing thermal degradation and metal-to-metal contact. As a direct replacement for the original factory component, the SKU 4644.121.239 guarantees exact fitment and flow characteristics. When paired with a properly sealed 4644101223: TRANSMISSION HOUSING or the 4644301225: TRANSMISSION HOUSING, this oil pipe forms the backbone of the internal oil distribution network.
Symptoms of Failure
- Visible oil leaks around the transmission bell housing: A cracked or corroded oil pipe will allow pressurized ATF to escape, leaving puddles under the vehicle and reducing overall fluid levels.
- Erratic gear engagement or slipping under load: Insufficient oil flow due to a blocked or deformed pipe starves the clutch packs, causing delayed shifts and power loss during acceleration.
- Overheating transmission with warning lamp activation: When the oil pipe fails to route fluid to the cooler circuit, internal temperatures spike rapidly, triggering thermal protection modes.
- Whining or grinding noises from the transmission sump: Air entrainment from a leaking pipe creates cavitation in the pump, producing audible distress signals during operation.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number (SKU) | 4644.121.239 |
| Material | Seamless steel tube with anti-corrosion coating |
| Overall Length | Approx. 320 mm |
| Tube Outer Diameter | 12 mm |
| Wall Thickness | 1.5 mm |
| Weight | 0.18 kg |
| OEM Reference | ZF 4644.121.239 |
| Sealing Interface | Compatible with 0634306525: O-RING and 0636305026: SCREW PLUG |
Compatibility
This oil pipe is engineered for the ZF WG180 and WG200 transmission families. It is a direct fit for all WG180 variants (including WG180-1, WG180-2) and WG200 models (WG200-3, WG200-4) used in medium-duty trucks, buses, and off-highway equipment. The pipe interfaces with the 0730365125: TYPE PLATE identification system and is secured by the 4644301298: COVER PLATE on the valve body assembly. Always verify your transmission serial number against the type plate before ordering.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101223 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301225 | TRANSMISSION HOUSING | Alternative housing variant for WG200 |
| 0730365125 | TYPE PLATE | Identification tag with transmission specs |
| 4644301298 | COVER PLATE | Seals valve body access port |
| 0634306525 | O-RING | Seals pipe-to-housing connection |
| 0636305026 | SCREW PLUG | Closes test ports on oil circuit |
| 4644301279 | SCREEN SHEET | Filters debris from oil flow |
| 4644301088 | SEALING CAP | Protects unused hydraulic ports |
| 4644106201 | SHIFT SYSTEM | Controls clutch engagement sequence |
| 4644306470 | GASKET | Prevents fluid leaks at mating surfaces |
