Caterpillar 346-6694 Air Filter, Secondary Element

The Element Nobody Orders Until It Is Missing

The primary element is the one that gets changed, photographed and discussed. The secondary element behind it — the safety element — is the one that gets forgotten until the day the housing is open and there is nothing to put back in. That is an expensive way to run a dozer. The safety element's whole job happens during the minutes when the primary is out of the housing and the engine is still drawing air, and in the failure case where a primary splits or seals badly. Neither situation announces itself in advance, so the sane routine is to keep the pair on the shelf rather than the outer alone.

On the square-shaped Caterpillar air cleaner, that pair is 539-6920 outside and 346-6694 inside. Cat's own parts pages group the two together, and the D6N dozer parts reference guide lists 346-6694 as the secondary element for the square-shaped housing — the same guide that puts 539-6920 on the square housing and 528-7222 on the round one.

Dimensions, Checked Against a Second Catalogue

Cat publishes 346-6694 at 6.594 in (167.5 mm) overall width, 1.484 in (37.7 mm) overall depth and 11.634 in (295.5 mm) overall height, non-round, standard-efficiency media, thermoplastic ends. Fleetguard's equivalent, AF4259, is published at 167 mm wide, 38 mm deep and 295.8 mm long with a 0.293 kg unit weight. Three figures, three agreements inside a millimetre — the kind of match that tells you the aftermarket number is the same element and not a similar-looking one, which matters when the element is thin and the housing seal depends on the end profile.

Practically, that also gives you a way to identify the element without a parts book: a flat non-round element roughly 6.6 in wide by 11.6 in tall in a square housing is this one. If what you have is round, roughly 8.4 in across and 16.3 in long, you are holding the circular-housing opposite number instead, and it belongs to a different air cleaner.

Which Machines, and Why This One Lists More Than Its Primary

The fitment list for 346-6694 runs from the D6N and D6K2 dozers through the D4, D5R2, 953K and 963K loaders to the AP600 to AP1055F and BG paver range, the M314F to M323F wheeled excavators, the PL61 pipelayer, the 140 GC grader, the MH3037 material handler and the 2384C through 579D knuckleboom loaders. It also picks up the 966F and 966F II wheel loaders, and that is worth flagging honestly: Cat's item page lists this secondary element on those loaders, but the primary element behind it is a different number, so a buyer who orders "539-6920 and 346-6694" for a 966F is only half right. Send the machine prefix and we check both positions rather than one.

The same element family is also catalogued by suppliers against machines outside our trade — Fendt Vario tractors, John Deere 6R tractors, Kleemann crushers and Vögele pavers all appear against HIFI's SA17483 equivalent. That is useful if you already buy on the HIFI number, and irrelevant if you buy on the Cat number. It also explains why this element is stocked in more places than a dozer-only part would be, which helps availability in Africa, the Middle East and South America.

346-6693 — the Number That Travels With It

Search this element and you will find supplier listings that quote 346-6693 and 346-6694 in the same product title, often with Mann CF2944, New Holland 73337833 and HIFI SA17483 alongside. Some listings pair 346-6693 with the primary-side numbers instead. Cat's D6N parts reference guide does not list 346-6693 against the square-housing machines at all; it lists 346-6694. So this page prints 346-6694 and treats 346-6693 as a separate number to be confirmed. If the old element in your hand is stamped 346-6693, send a photo with the measurements and we will tell you which of the two your housing takes before you order either.

What We Do Not Publish

No price on the page, because quantity, lane and whether you take the pair or the full service kit decide the number. No claim that this element fits every machine it has ever been listed against, because the 966F case above shows exactly why that would be wrong. And no operating-hour interval — Cat sets secondary element servicing as every third primary change or as required, per machine and duty cycle, and a web page is a poor place to guess. Send the serial prefix off the PIN plate, the air cleaner group number, or the old element with a tape measure, and we confirm the primary and the secondary for your machine, quote both, and dispatch in 3–7 days.

FAQ

Q: What is Cat 346-6694?
A: 346-6694 is the secondary or safety engine air filter element for the square-shaped Caterpillar air cleaner housing, cross-referenced to Caterpillar OEM 346-6694. It sits behind the primary element 539-6920 on D6N and D6K2 dozers, D4 and D5R2 dozers, 953K and 963K track loaders, the AP600 to AP1055F and BG paver range, the M314F to M323F wheeled excavators and other machines on the same air cleaner. Cat publishes 6.594 in wide, 1.484 in deep and 11.634 in high, non-round, standard-efficiency media.

Q: Can I clean a Cat secondary air filter instead of replacing it?
A: No. Cat's own filters guidance says the secondary element should never be cleaned, and should be replaced with every third primary element change or as required. Blowing it out with compressed air pushes the dust it has held back through the media, so a cleaned safety element protects the engine less than the dirty one you took out. It is a thin, low-cost element, which is exactly why it should be treated as a consumable and not as a permanent part of the housing.

Q: Is 346-6694 the same as 346-6693?
A: They are different numbers and we do not treat them as interchangeable. Cat's D6N parts reference guide lists 346-6694 as the secondary element for the square-shaped air cleaner housing, and it does not list 346-6693 against those machines at all. Supplier catalogues do group 346-6693 next to 346-6694, and some single listings quote one for the other, which is where the confusion comes from. If your old element or your parts book shows 346-6693, send us a photo and we confirm the pair before quoting.

Q: Which cross reference numbers are listed against Cat 346-6694?
A: The numbers that come up against 346-6694 in supplier catalogues are HIFI SA17483, Fleetguard AF4259, Baldwin PA30268, MANN CF2944, New Holland 73337833, Fendt H737200092110, SF-FILTER SL82513, WIX WA10561 (NAPA 500561), Hengst E1664LS and Liebherr 12265206. The Fleetguard number is a useful check because its published measurements — 38 mm deep, 295.8 mm long and 167 mm wide — match Cat's 1.484 in, 11.634 in and 6.594 in within a millimetre. We still treat catalogue numbers as leads to verify against dimensions, not as proof of fit.