Overview
The ZF 6073.015.204 EST 37 A for WG171 is a critical electro-hydraulic control unit designed to manage shift timing and pressure modulation within the WG 171 series transmission. This OEM genuine part, identified by SKU 6073.015.204, sits directly atop the valve body assembly and interfaces with the main transmission housing to regulate clutch and brake engagement. By converting electronic signals from the transmission control module into precise hydraulic actions, this component ensures smooth gear transitions under heavy load conditions. It works in concert with the 4656101028: TRANSMISSION HOUSING to maintain proper fluid routing and pressure integrity.
Symptoms of Failure
- Erratic shifting or gear hunting — When the EST 37 A solenoid pack degrades, the transmission may fail to hold a gear or randomly shift between ratios, especially during uphill climbs or under heavy payloads.
- Delayed engagement from Neutral to Drive — A worn unit causes a noticeable lag of 2-4 seconds when selecting a forward gear, often accompanied by a harsh clunk as pressure finally builds.
- Transmission overheating with fluid contamination — Internal seal failure within the 6073.015.204 allows debris to circulate, leading to elevated operating temperatures and dark, burnt-smelling ATF.
- Intermittent loss of reverse gear — A failing control unit may cause reverse to engage only intermittently or slip under load, a symptom often searched as “ZF WG171 reverse gear slipping.”
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 6073.015.204 |
| OEM Reference | ZF EST 37 A for WG171 |
| Material | Aluminum alloy housing with steel spool valves |
| Weight | 2.8 kg (6.2 lbs) |
| Dimensions (L x W x H) | 210 mm x 140 mm x 95 mm |
| Operating Pressure Range | 8-22 bar (116-319 psi) |
| Fluid Temperature Range | -20°C to +120°C |
| Seal Type | Nitrile rubber (NBR) |
Compatibility
This genuine ZF 6073.015.204 EST 37 A is specifically engineered for the WG 171 series transmission family. It is also compatible with select WG 180 and WG 200 models that share the same valve body architecture, though cross-referencing with your transmission serial number is recommended. The unit directly mounts to the 4656301066: HOUS.FRONT SECT and requires the 4656201015: SCREEN SHEET to be installed upstream for filtration. Additionally, the 4656301037: TUBE must be properly seated to ensure correct fluid flow to the control unit.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4656101028 | TRANSMISSION HOUSING | Main structural casing for gear sets and valve body |
| 4656301066 | HOUS.FRONT SECT | Front section housing for pump and torque converter |
| 4656201015 | SCREEN SHEET | Fine mesh filter protecting valve body from debris |
| 4656301037 | TUBE | Fluid transfer tube between pump and control unit |
| 0634313514 | O-RING | Seals fluid passages to prevent external leaks |
| 0636100803 | CAP SCREW | M8 fastener for securing valve body to housing |
| 4656301042 | HOUSING REAR PART | Rear cover housing for output shaft and speed sensors |
| 0631306816 | CYLINDRICAL PIN | Alignment dowel for precise component positioning |
| 0636100801 | CAP SCREW | M6 fastener for securing solenoid cover plate |
| 0636100160 | CAP SCREW | M10 fastener for transmission housing bolts |
Frequently Asked Questions
Q: Can the 6073.015.204 be repaired, or must it be replaced?
A: This EST 37 A unit is a sealed electro-hydraulic assembly. Internal solenoid wear or valve body scoring typically necessitates full replacement rather than repair, as individual components are not serviceable separately.
Q: What torque specification should be used when installing this part?
A: The mounting bolts for the 6073.015.204 should be torqued to 25 Nm (18 ft-lbs) in a crosswise pattern. Always use new O-rings from the related components list to prevent fluid bypass.
Q: How do I verify this part fits my WG171 transmission?
A: Check the transmission data plate for the model code “WG171” and the serial number. The 6073.015.204 is also stamped with “EST 37 A” on the solenoid cover for visual confirmation.
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