Overview
The ZF 4644.121.031 OIL PIPE is a precision-engineered fluid conduit designed for the lubrication and cooling circuits within ZF WG180 and WG200 series transmissions. This OEM genuine part ensures a consistent flow of hydraulic oil to critical bearing surfaces and clutch packs, directly supporting thermal regulation and component longevity. The SKU 4644.121.031 is a direct replacement for the original factory-installed pipe, maintaining the exact internal diameter and routing geometry required for proper pressure distribution. When installed alongside the 4644101043 TRANSMISSION HOUSING or the 4644301194 TRANSMISSION HOUSING, this oil pipe forms a sealed, high-pressure oil gallery that prevents cross-contamination between lubrication circuits.
Symptoms of Failure
- Visible oil leaks at the transmission casing: A cracked or corroded 4644.121.031 oil pipe will cause ATF fluid to weep from the joint area, often mistaken for a housing seal failure. This is a common long-tail search query for “ZF WG180 oil leak from pipe.”
- Delayed gear engagement or slipping: Insufficient oil delivery due to a restricted or fractured pipe reduces clutch pack pressure, leading to hesitation when shifting from Neutral to Drive or Reverse.
- Overheating transmission fluid: A blocked oil pipe disrupts the flow to the cooler circuit, causing the transmission to run 15-20°C hotter than normal under load.
- Whining or groaning noise from the pump: Air ingestion through a cracked pipe creates cavitation noise, particularly noticeable at idle or low RPM.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4644.121.031 |
| Material | Seamless drawn steel with zinc-nickel plating |
| Overall Length | 285 mm (estimated) |
| Tube Outer Diameter | 12 mm |
| Wall Thickness | 1.5 mm |
| Weight | 0.18 kg |
| OEM Reference | ZF 4644.121.031 |
| Sealing Method | O-ring groove at both ends |
Compatibility
This oil pipe is engineered for ZF WG180 and WG200 series transmissions, including all sub-variants such as WG180-110, WG180-120, WG200-110, and WG200-130. It is also compatible with certain ZF Ecomat 4HP and 5HP models that share the same oil gallery architecture. The pipe interfaces directly with the 0730365067 TYPE PLATE which identifies the correct transmission variant, and is secured using the 0631311009 GROOVED STUD to prevent rotational movement under vibration. Always verify the part number stamped on the existing pipe before replacement.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101043 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301194 | TRANSMISSION HOUSING | Alternate housing variant for WG200 |
| 0730365067 | TYPE PLATE | Identification plate for transmission model |
| 0631311009 | GROOVED STUD | Retaining stud for oil pipe alignment |
| 4644303060 | COVER PLATE | Access cover for valve body area |
| 4644303061 | COVER PLATE | Alternate cover plate with gasket |
| 0634801098 | SEALING RING | O-ring for oil pipe connection |
| 0634801250 | SEALING RING | Larger O-ring for housing interface |
| 0636305026 | SCREW PLUG | M18 plug for test port |
| 0636305019 | SCREW PLUG | M16 plug for drain port |
