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WIX Filters · 51xxx · return line

51738 filter element: specifications & equivalents

The 51738 is a WIX Filters return-line hydraulic filter element, built with paper media, sized 82.9 × 203.2 mm OD × length (ID 41.9 mm). Verify against the current manufacturer data sheet before ordering.

Envelope OD × L 82.9 × 203.2 mm
Inside diameter 41.9 mm
Media Paper
Line type return
Catalog verified. Parameters extracted from the manufacturer’s electronic catalog / official interchange document and checked 2026-09-27. Confidence score 0.90.

Specification table

ParameterValue
Filter type return line
Media Paper
Rating basis nominal
Outside diameter OD 82.9 mm
Inside diameter ID 41.9 mm
Length 203.2 mm
End caps open-ended cartridge element (no baseplate)
Flow direction outside-in
Integral bypass valve none (housing/valve-dependent)
Seal material Nitrile (NBR)
Manufacturer part no. 51738
Source catalog WIX Filters (MANN+HUMMEL): WIX Filters online product catalog
Last verified2026-09-27

Sources: WIX Filters (MANN+HUMMEL) — WIX Filters online product catalog — accessed 2026-09-26.

WIX Filters® and all model designations are trademarks of their respective owners, used here for identification only — ElementRef is an independent reference site, not an authorized WIX Filters distributor.

Dimensions & series range

Outside diameter82.9 mm (3.264 in)
Inside diameter41.9 mm (1.650 in)
Overall length203.2 mm (8.000 in)

Cross references & equivalents

No catalog-verified cross references yet. This model is in the manual verification queue — request a verified equivalent.

Interchange levels: full catalog-confirmed drop-in · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.

How the 51738 model number is decoded

  • 51738WIX hydraulic cartridge element part number.
  • 82.9 mm OD / 41.9 mm IDCartridge envelope (outside/inside diameter); no mounting thread.
  • PaperFilter media: Paper.

Typical equipment & applications

  • Mobile and industrial hydraulic return circuits
  • Construction and agricultural equipment
  • Heavy-duty transmission and torque-converter circuits

Selection pitfalls — read before you substitute

  • A return-line element is not a pressure-line element: return cartridges (BN4HC low-collapse) tolerate roughly 20 bar differential, while BH4HC pressure executions are rated to 210 bar. Installing a low-collapse element in a pressure housing can rupture the media on cold-start spikes.
  • This element has no integral bypass — opening pressure is set by the housing’s reusable bypass valve. Confirm the valve setting (commonly 3.4 bar) is present before fitting.
  • “10 µm nominal” and “12 µm at β1000” can describe the very same media — one is reported at β≥200, the other at β≥1000 per ISO 16889. Compare ratings at the same Beta test point, not just the printed micron number.
  • Nitrile (NBR) seals are standard for mineral hydraulic oil but fail early in some phosphate-ester fluids and at sustained high temperature; verify seal compound against the fluid data sheet (fluorocarbon/Viton executions may be required).
  • End-cap geometry and the number/position of O-rings block interchange even when OD and length match — visually compare end caps before fitting, especially with aftermarket cartridges.

Frequently asked questions

What are the dimensions of the 51738 filter element?
The published envelope is 82.9 mm OD × 203.2 mm length with a 41.9 mm inside diameter (3.264 × 8.000 in × 1.650 in ID). Confirm against the housing drawing before ordering.
What replaces the 51738 filter element?
Cross references are being verified for this model — use the inquiry form and the engineering desk will confirm equivalents.
How do I read the 51738 part number?
See the designation decoder above: each segment of 51738 encodes size, line type, filtration grade and media/collapse execution.
Is a same-envelope aftermarket element always a drop-in replacement?
No. Matching OD and length only proves the cartridge fits the bowl. End-cap style, seal compound, micron/Beta rating, collapse pressure and bypass configuration must also match; the table above tags every equivalent as full, partial or verify for exactly this reason.
How often should a hydraulic return-line element be replaced?
Replace at the housing manufacturer’s recommended differential-pressure setting (commonly signalled by a clogging indicator), or on a time-based service interval when no indicator is fitted — never wait for bypass to open continuously, because unfiltered oil then reaches the valves.

Other models in the 51xxx series

All 306 →
51089 74×144 mm · 32 µm 51096 115×183 mm · 5 µm 51097 114×231 mm · 10 µm 51098 115×227 mm · 23 µm 51113 129×228 mm · 5 µm 51116 94×198 mm · 11 µm 51119 115×229 mm · 23 µm 51120 94×198 mm · 9 µm 51127 88×235 mm · 32 µm 51134 152×216 mm · 10 µm

Reviewed & verified by the ElementRef engineering desk against WIX Filters (MANN+HUMMEL) on 2026-09-27. Read our editorial & correction policy.