Overview
The ZF 4651.321.012 SUCTION TUBE is a critical hydraulic component engineered specifically for the WG 100 Series transmission family. This OEM genuine part serves as the primary conduit for drawing transmission fluid from the sump into the hydraulic pump, ensuring consistent lubrication and cooling flow throughout the gear train. Positioned within the lower valve body assembly, the suction tube (SKU: 4651.321.012) maintains a sealed pathway that prevents air ingestion, which can compromise shift quality. This tube works in concert with the 4651101009: TRANSMISSION HOUSING to form a leak-proof fluid circuit, while the 0634303928: O-RING provides the necessary seal between the tube and its mounting bore.
Symptoms of Failure
- Low fluid pressure and gear slipping: A cracked or deformed suction tube allows air to mix with the oil, causing the hydraulic system to lose prime. This results in delayed engagement or complete gear slip under load.
- Audible whining or cavitation noise: When the suction tube develops pinholes or fractures, the pump draws in air, producing a distinct high-pitched whine that intensifies during acceleration.
- Visible oil leaks at the transmission pan area: Deterioration of the tube’s sealing surface or the associated 0634303928: O-RING leads to fluid weeping around the suction port, often mistaken for a pan gasket failure.
- Intermittent transmission overheating: Insufficient fluid volume reaching the pump due to a compromised suction path reduces cooling capacity, causing erratic temperature spikes during operation.
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number | 4651.321.012 |
| Material | Die-cast aluminum alloy with corrosion-resistant coating |
| Overall Length | 215 mm (8.46 in) |
| Tube Inner Diameter | 18 mm (0.71 in) |
| Weight | 0.34 kg (0.75 lbs) |
| OEM Reference | ZF 4651.321.012 (Genuine) |
| Sealing Interface | Compatible with 0634303928: O-RING |
Compatibility
This suction tube is designed for the ZF WG 100 Series, but its application extends to several related transmission models that share the same hydraulic architecture. The part is a direct fit for the WG180, WG200, and WG210 transmissions produced between 2005 and 2020. It also retrofits into the WG 150 series when used with the appropriate 4651301025: HOUSING adapter. For installations requiring additional structural support, the 4651301031: HOUSING provides the necessary mounting reinforcement. Always verify the condition of the 0634303928: O-RING during replacement to ensure a proper seal.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4651101009 | TRANSMISSION HOUSING | Main structural casing that encloses the gear train and hydraulic circuits |
| 4651301025 | HOUSING | Intermediate adapter housing for valve body alignment |
| 0634303928 | O-RING | Sealing ring for suction tube mounting bore |
| 4651301031 | HOUSING | Reinforced housing section for high-torque applications |
| 4651203002 | SCREEN SHEET | Fine mesh filter protecting the suction inlet from debris |
| 4651303005 | SCREEN SHEET | Secondary filtration screen for the hydraulic return circuit |
| 0636101032 | CAP SCREW | Fastener for securing the suction tube bracket |
| 0630361028 | SEALING CAP | Protective cap for unused hydraulic ports |
| 4475280060 | SCREW PLUG | Threaded plug for sealing test ports |
| 0634303312 | O-RING | Seal for the screw plug interface |
