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Cummins Oil Filters
Fleetguard LF3994 Oil Filter
The Fleetguard LF3994 oil filter is a spin-on bypass lube filter, not a full-flow filter. Its principal application is Thermo King refrigeration-unit engines, and it is not interchangeable with the LF9009 full-flow filter fitted to Cummins engines. Confirm the unit record, installed position and old part number before ordering.
- Part number
- LF3994
- Type
- Spin-on bypass lube filter
- Application reference
- Thermo King 119101 (11-9101), to be confirmed
Availability and delivery terms confirmed with quotation.
What LF3994 Is, and What It Is Not
The LF3994 is a spin-on canister: element and housing in one unit, threaded onto a filter head and sealed by a gasket. It carries a 3/4-20 UNEF-2B thread and is listed without a bypass valve or an anti-drainback valve.
The word that matters here is bypass. A bypass lube filter filters a side stream of oil continuously at a finer level; it does not carry the full oil flow. That is a different job from a full-flow filter, and the two are not interchangeable.
The confusion to avoid is the sibling number. LF9009 is a full-flow and bypass combination filter for Cummins ISC, ISL, ISM, M11, N14 and NTA 855 engines, with a 2.25-12 thread. LF3994 is a smaller bypass-only filter with a 3/4-20 thread. The thread, envelope and job differ.
-
Bypass, not full-flow
It filters a side stream of oil and must not be treated as a full-flow filter.
-
Not interchangeable with LF9009
LF9009 has a 2.25-12 thread and a different engine list.
-
Unit-led application
Thermo King refrigeration-unit engines are the principal application reference.
LF3994 Specifications
We publish only the interface fields that agree across listings. Outer diameter and length are withheld: listings conflict, and a copied figure is not evidence. Those values are confirmed against the manufacturer specification for your unit and stated in your quotation.
| Check | Value to compare | How to confirm |
|---|---|---|
| Thread | 3/4-20 UNEF-2B | Match the old element |
| Bypass valve | Not fitted | Check the filter head |
| Anti-drainback valve | Not fitted | Check the filter head |
| Application reference | Thermo King 119101 (11-9101) | Check the unit record |
| Direct cross-reference | Donaldson P553746 | Treat as a candidate |
| Outer diameter, length | Not published | Confirmed per quotation |
Swipe horizontally to view all columns.
Three Records That Have to Agree
-
The unit or engine record
Maker, model and full serial or build number. For a reefer unit, that means the Thermo King model and the engine it carries.
-
The installed position
Which head the element came from, and whether the engine also runs a full-flow filter alongside it.
-
The complete number on the removed element
Include any suffix. Where the parts record, manual and old element disagree, send all three.
LF3994 and LF9009 Are Not Interchangeable
LF9009 is the full-flow and bypass combination filter for Cummins ISC, ISL, ISM, M11, N14 and NTA 855 engines, with a 2.25-12 thread, replacing Cummins 3401544. LF3994 is a bypass-only filter with a 3/4-20 thread, listed for Thermo King reefer units under the principal reference 119101. The thread, envelope and function all differ. Order the number you can evidence; accept a substitution only when the quotation names it.
LF3994 Cross-References Are Candidates, Not Confirmations
| Brand | Candidate reference |
|---|---|
| Donaldson | P553746 |
| Baldwin | B128, 15326 |
| Mann | W11181 |
| Caterpillar | 3I1277, 9Y4485 |
| Hastings | LF435, P435 |
| WIX | 51802 |
| Luber-Finer | LFP3746 |
| Thermo King | 119101, 113746, 1389323 |
Candidate references only. Lists differ between sellers in length and membership.
Applications, and How an LF3994 Order Is Quoted
Start with the unit, not the filter.
Thermo King refrigeration-unit engines
Applications are unit-led: Thermo King refrigeration-unit engines, where the unit’s own record — not the filter’s cross-reference — confirms the fit. The number also reaches industrial and refrigeration equipment lists by cross-reference; confirm those on the machine’s own record.
Industrial cross-references also require a check against the machine’s parts record.
Know exactly what is being quoted.
We check each line against the parts record and position, then state the offered item, maker, complete number, quantity and delivery terms.
No real-time stock feed is published; availability is confirmed against your list.
Request a QuoteFrequently Asked Questions
Is LF3994 a full-flow or a bypass oil filter?
It is a bypass lube filter: it filters a side stream of oil at a finer level, not the full flow. Do not treat it as a full-flow filter, and do not substitute LF9009, which is a different filter for different engines.
What is LF3994 used for?
Thermo King refrigeration-unit engines, principally. Thermo King 119101 is the application reference most often cited. Confirm the exact fit against the unit’s own record.
What is the difference between LF3994 and LF9009?
LF9009 is a full-flow and bypass combination filter for Cummins ISC, ISL, ISM, M11, N14 and NTA 855 engines with a 2.25-12 thread; LF3994 is a smaller bypass-only filter with a 3/4-20 thread. They are not interchangeable.
Is Donaldson P553746 the same as LF3994?
It is the direct cross-reference most often cited. Treat it as a candidate to review and confirm against the parts record for your unit before ordering.
Confirm the Number, Then Confirm the Unit
The LF3994 is quoted against a unit record, a position and a number, in that order. Send the unit or engine model, serial or build number and the number printed on the element you are removing.