Overview
The ZF 4644.121.085 OIL PIPE is a critical fluid delivery component engineered specifically for the WG180 and WG200 transmission series. This OEM genuine part channels pressurized hydraulic oil from the valve body to the rotating clutch packs and planetary gear sets, ensuring consistent lubrication and cooling under heavy-duty industrial loads. Positioned within the transmission’s internal oil circuit, the 4644.121.085 pipe maintains precise flow rates essential for smooth gear engagement and thermal regulation. As a direct OEM replacement, this SKU guarantees exact fitment and material integrity, eliminating the risk of aftermarket dimensional variances that can compromise transmission performance.
Symptoms of Failure
- Transmission oil leaks at the pipe connection points: A cracked or corroded 4644.121.085 OIL PIPE often causes visible fluid seepage near the transmission housing or valve body, leading to low oil levels and eventual overheating.
- Erratic gear slipping under load: When this pipe becomes blocked or develops internal fractures, hydraulic pressure drops, causing delayed or incomplete clutch engagement—especially noticeable during uphill hauling or sudden acceleration.
- Whining or humming noise from the transmission sump: Restricted oil flow through a damaged pipe creates cavitation, producing a distinct high-pitched sound that worsens as fluid temperature rises.
- Overheating and burnt oil smell: Insufficient lubrication due to a failing oil pipe accelerates friction between moving parts, generating excess heat and a characteristic acrid odor from degraded transmission fluid.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (SKU) | 4644.121.085 |
| Product Name | OIL PIPE |
| Material | Seamless cold-drawn steel with anti-corrosion coating |
| Overall Length | 185 mm (estimated) |
| Outer Diameter | 12 mm |
| Wall Thickness | 1.5 mm |
| Weight | 0.14 kg |
| OEM Reference | ZF 4644.121.085 |
| Thread Type | M10 x 1.0 (both ends) |
Compatibility
This genuine ZF OIL PIPE is designed for the WG180 and WG200 series transmissions, which are widely used in municipal trucks, construction loaders, and agricultural machinery. It directly replaces the original pipe in models such as the WG180-5, WG180-6, WG200-5, and WG200-6. The part interfaces with the 4644105475: DISCONNECTION fitting and the 4642303097: OUTPUT FLANGE assembly. For secure mounting, use the 0636020211: HEXAGON SCREW to fasten the pipe bracket to the 4644101134: TRANSMISSION HOUSING. Always verify your transmission’s serial number against ZF’s compatibility charts before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644105475 | DISCONNECTION | Hydraulic quick-connect for oil line service |
| 4642303097 | OUTPUT FLANGE | Connects transmission to driveshaft |
| 0636020211 | HEXAGON SCREW | Fastens pipe bracket to housing |
| 4644101134 | TRANSMISSION HOUSING | Main structural casing for gear assembly |
| 4644301349 | HOUSING | Internal support for clutch pack |
| 0730365125 | TYPE PLATE | Identification tag for transmission model |
| 0631311009 | GROOVED STUD | Alignment pin for oil pipe positioning |
| 0636305019 | SCREW PLUG | Seals unused oil port openings |
| 4644301247 | THREADED BUSH | Reinforces pipe connection threads |
| 0634303485 | O-RING | Prevents fluid leakage at joints |
