WIX Filters · 51xxx · return line

51257 filter element: specifications & equivalents

Q: What are the dimensions of the 51257 filter element?

The published envelope is 128.5 mm OD × 155.5 mm length with a 65.3 mm inside diameter (5.059 × 6.122 in × 2.571 in ID). Confirm against the housing drawing before ordering.

Q: What micron rating does 51257 use?

This element is rated 19 µm (nominal class). Always compare Beta ratings at the same test point: two brands may print different micron numbers for the same physical grade.

The 51257 is a WIX Filters return-line hydraulic filter element, built with paper media, sized 128.5 × 155.5 mm OD × length (ID 65.3 mm), rated at 19 µm class. Verify against the current manufacturer data sheet before ordering.

Envelope OD × L 128.5 × 155.5 mm

Inside diameter 65.3 mm

Filtration rating 19 µm nom.

Media Paper

Line type return

Catalog verified. Parameters extracted from the manufacturer’s electronic catalog / official interchange document and checked 2026-09-28. Confidence score 0.90.

Specification table

Parameter	Value
Filter type	return line
Media	Paper
Filtration rating	19 µm
Rating basis	nominal
Outside diameter OD	128.5 mm
Inside diameter ID	65.3 mm
Length	155.5 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.	51257
Source catalog	WIX Filters (MANN+HUMMEL): WIX Filters online product catalog
Last verified	2026-09-28

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.

Dimensional drawing

Reference drawing generated from the source values cited on this page — nominal envelope, schematic section, not a manufacturer drawing. The PDF is A3 landscape and vector; the PNG is sized for a WhatsApp preview. Confirm thread, end caps, seal compound and micron/Beta grade against the original element before ordering.

Dimensions & series range

Outside diameter	128.5 mm (5.059 in)
Inside diameter	65.3 mm (2.571 in)
Overall length	155.5 mm (6.122 in)

All 129×156 mm interchange elements →

Cross references & equivalents

Equivalent model	Brand	Match level	Note
↔ HF6018	Fleetguard	partial	Fleetguard's online catalog lists 51257 as an interchange for HF6018. Envelope cross-reference; verify micron grade, collapse rating and seal configuration before substituting.

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.

Full chart: WIX Filters cross reference chart →

How the 51257 model number is decoded

51257WIX hydraulic cartridge element part number.
128.5 mm OD / 65.3 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

Line type is not interchangeable: return-line cartridges are low-collapse executions that typically tolerate roughly 10–20 bar differential, while pressure-line elements are commonly rated 100–210 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.
This execution uses nitrile (nbr) seals — verify the compound against the fluid data sheet: standard nitrile (NBR) can fail early in phosphate-ester fluids and at sustained high temperature, where 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 51257 filter element?

The published envelope is 128.5 mm OD × 155.5 mm length with a 65.3 mm inside diameter (5.059 × 6.122 in × 2.571 in ID). Confirm against the housing drawing before ordering.

What micron rating does 51257 use?

This element is rated 19 µm (nominal class). Always compare Beta ratings at the same test point: two brands may print different micron numbers for the same physical grade.

What replaces the 51257 filter element?

1 partial match(es) requiring parameter review

How do I read the 51257 part number?

See the designation decoder above: each segment of 51257 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 filter 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.

Same-envelope elements from other brands

View full interchange →

These 2 catalog element(s) share the 129×156 mm envelope. Envelope match alone does not guarantee interchangeability — compare micron/Beta, seals and collapse rating.

HF6018 Fleetguard 51179 WIX Filters · 32 µm

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 2026-09-28. Read our editorial & correction policy.