Overview
The ZF 4700.280.019 RELIEF VALVE is a precision-engineered hydraulic component designed to regulate system pressure within ZF WG-series automatic transmissions. This OEM genuine part, identified by SKU 4700.280.019, sits within the valve body assembly and serves as a critical safety mechanism. Its primary function is to divert excess hydraulic fluid back to the sump when pressure exceeds operational thresholds, protecting seals, clutches, and the torque converter from over-pressurization. When installed alongside the 4108101057 HOUSING and the 4108201177 HOUSING, this relief valve ensures consistent lubrication and shift quality across the transmission’s hydraulic circuit.
Symptoms of Failure
- Erratic or delayed gear engagement: A worn relief valve can cause pressure fluctuations, leading to harsh shifts or hesitation when moving from Neutral to Drive.
- Hydraulic fluid leaks near the valve body: A stuck or fatigued valve may allow fluid to bypass the 0636302056 SCREW PLUG or adjacent sealing surfaces, resulting in visible oil seepage.
- Torque converter shudder or overheating: Insufficient pressure regulation can cause the converter to slip, generating excessive heat and reducing transmission efficiency.
- Intermittent loss of forward or reverse pressure: When the relief valve fails to close properly, the system may dump pressure, causing temporary loss of drive.
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number (SKU) | 4700.280.019 |
| OEM Reference | ZF 4700.280.019 |
| Material | Hardened steel with zinc-nickel plating |
| Overall Length | 42 mm (approx.) |
| Valve Diameter | 18 mm (approx.) |
| Weight | 0.08 kg (0.18 lbs) |
| Cracking Pressure | 8.5–10.0 bar (factory set) |
| Seat Type | Poppet with O-ring seal |
Compatibility
This relief valve is engineered for ZF WG-series transmissions, specifically the WG100, WG130, and WG131 models. It is also compatible with the WG180 and WG200 variants when used in hydraulic circuits requiring a 10-bar pressure limit. For proper installation, always pair this valve with a new 4108301304 BEARING COVER and inspect the 4108306173 GASKET for wear. The valve interfaces directly with the control cover assembly, making it essential for rebuilds of WG100, WG130, and WG131 units.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4108101057 | HOUSING | Encloses valve body and directs oil flow |
| 4108201177 | HOUSING | Secondary housing for pressure regulation |
| 0636302056 | SCREW PLUG | Seals hydraulic passages in the valve body |
| 4108301304 | BEARING COVER | Protects output shaft bearing from debris |
| 4108306173 | GASKET | Prevents fluid leaks between mating surfaces |
| 0750110040 | SHAFT SEAL | Seals rotating shaft against oil leakage |
| 6053108155 | CONTROL COVER | Houses shift solenoids and valve spools |
| 6053308348 | CONTROL COVER | Alternate cover for WG130/WG131 models |
| 0636010188 | HEXAGON SCREW | M8 bolt for securing valve body components |
| 0636010192 | HEXAGON SCREW | M10 bolt for heavy-duty mounting points |
