WIX Filters · 51xxx · return line
51859 filter element: specifications & equivalents
The 51859 is a WIX Filters return-line hydraulic filter element, built with paper media, sized 127.2 × 285.9 mm OD × length, rated at 5 µm class. Verify against the current manufacturer data sheet before ordering.
Envelope OD × L 127.2 × 285.9 mm
Filtration rating 5 µm nom.
Media Paper
Thread 1 1/2-16
Collapse / burst 23.8 bar
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 | 5 µm |
| Rating basis | nominal |
| Outside diameter OD | 127.2 mm |
| Length | 285.9 mm |
| Thread / connection | 1 1/2-16 |
| End caps | spin-on baseplate with attached gasket |
| Flow direction | outside-in |
| Collapse / burst pressure | 23.8 bar |
| Integral bypass valve | opens at 1.4 bar |
| Seal material | Nitrile (NBR) |
| Manufacturer part no. | 51859 |
| 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
Dimensions & series range
| Outside diameter | 127.2 mm (5.008 in) |
| Overall length | 285.9 mm (11.256 in) |
All 127×286 mm interchange elements →
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| ↔ BT345 | Baldwin Filters | partial | Baldwin's Form 561 Number-Finder cross-reference lists 51859 (KIT) as replaced by Baldwin BT345. Form/fit listing without published performance data — verify micron grade, collapse rating and seal configuration before substituting. |
| ↔ HF6348 | Fleetguard | partial | Fleetguard's online catalog lists 51859 as an interchange for HF6348. Envelope cross-reference; verify micron grade, collapse rating and seal configuration before substituting. |
| ↔ WD13010-2X | MANN-FILTER | partial | MANN-FILTER's online catalog lists 51859 (WIX) as a comparison number for WD130102X. 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 51859 model number is decoded
- 51859WIX hydraulic spin-on filter part number.
- 1 1/2-16Mounting thread: 1 1/2-16 (spin-on baseplate).
- 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 execution carries an integral bypass valve (opens at 1.4 bar). The same envelope also exists without it, relying on the housing valve. Mixing the two strategies changes cold-start protection — match what was installed originally.
- “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.
- Fine 5 µm media loads faster and runs at a higher cold Δp than coarser grades — only downgrade cleanliness targets if the system ISO 4406 code allows it.
- 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 51859 filter element?
The published envelope is 127.2 mm OD × 285.9 mm length (5.008 × 11.256 in). Confirm against the housing drawing before ordering.
What micron rating does 51859 use?
This element is rated 5 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 51859 filter element?
3 partial match(es) requiring parameter review
How do I read the 51859 part number?
See the designation decoder above: each segment of 51859 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 127×286 mm envelope. Envelope match alone does not guarantee interchangeability — compare micron/Beta, seals and collapse rating.
Other models in the 51xxx series
All 306 →Reviewed & verified by the ElementRef engineering desk against WIX Filters (MANN+HUMMEL) on 2026-09-28. Read our editorial & correction policy.