Caterpillar 523-4987 Element-Separator

An Element, Not a Separator Assembly

The name Cat gives this part — Element-Separator — is the important detail. On the Next Gen machines the water separator is a housing that stays bolted to the machine, with a drain and a filter head; 523-4987 is the serviceable element that goes inside it. So when a workshop says "the separator needs changing", the part on the invoice is this one, and the housing, head and drain valve are not being replaced. That is also why the number is filed under Fuel Water Separators in Cat's catalogue while the phrase people search for is "fuel filter" — the same search that pulls up the secondary element 509-5694.

Cat's own description copy for the page explains the design intent: Ultra High Efficiency fuel water separators are built to extend the life of the secondary filter and precision fuel system components, and the media is Meltblown with glass-filled nylon end caps, roving fibre glass impregnated with epoxy resin. Free water is what kills unit injectors — diesel acts as a lubricant in the injector, and water breaks the film strength that stops metal-to-metal contact. A separator element is cheap insurance against an injector set.

The Pair: 523-4987 and 509-5694 Are Not Interchangeable

Both elements are cartridges with out-to-in flow and polyamide plastic construction, so they look alike on a bench and both arrive in kits labelled with the same machine model. The published sizes settle it:

	523-4987 (this element)	509-5694 (secondary element)
Cat's part name	Element-Separator	Secondary Fuel Filter Element
Catalogue branch	Engine Filters > Fuel Water Separators	Engine Filters > Fuel Filters
Diameter	4.043 in — 102.7 mm	3.484 in — 88.5 mm
Length	10.169 in — 258.3 mm (description line: 250.3 mm)	6.654 in — 169 mm
Efficiency category	Ultra High Efficiency	Not stated on Cat's sheet
Position in the line	Upstream, in the water separator housing	Downstream, second of the two

Cat's lists are not identical either, and this is where most wrong orders start. The separator element covers a wider machine set than the secondary element: 316 GC and the 340, 345, 345 GC and 350 excavators appear under 523-4987, as do the MH3050 and MH3250 material handlers and the 336MHPU and 340MHPU power units. A 350 uses the separator number — ordering "the pair" for every C4.4 machine is not the same as reading the parts book.

Where This Element Turns Up

Machine family	Models on Cat's list for 523-4987
Excavators	316 GC, 320, 320 GC, 320 GX, 323, 323 GC, 323 GX, 325, 326, 326 GC, 330, 330 GC, 333, 333 GC, 335, 336, 336 GC, 340, 345, 345 GC, 350
Forestry excavators	FM538, FM548, FM558, FM568
Wheeled excavators	M314, M315, M315 GC, M316, M317, M318, M320, M320 GC, M322, MH3026, MH3040
Material handlers	MH3022, MH3024, MH3032, MH3040, MH3050, MH3250
Wheel loaders	926, 930, 938, 950, 962
Motor graders	120 GC, 140, 140 GC
Mobile hydraulic power units	330 MHPU, 336MHPU, 340MHPU
Forestry	538, 548, 558, 568, FM528, FM528 LL
Industrial engine	C4.4

For a fleet buyer the practical read is that this is a shelf item for a mixed fleet, not a single-machine part: one separator element number covers C4.4 excavators, wheeled excavators, wheel loaders and motor graders. If you run 320 GC and 330 GC machines alongside 962 loaders, one bin covers them.

The Length Cat Prints Twice

Cat's specification sheet for 523-4987 gives Length 10.169 in — 258.3 mm. The attribute line in the description block on the same page gives 250.3 mm (9.85 in). Both are live on parts.cat.com today, and an 8 mm difference on a cartridge that has to seal in a housing is not cosmetic. We publish both figures instead of choosing one, and we ask for the diameter and length of the element you are removing, or a photo of it next to a tape measure. The diameter is not in dispute — 4.043 in (102.7 mm) on both Cat pages and on the aftermarket catalogues that list the number.

What We Do Not Publish

No price, because quantity, lane and kit content decide it. No hour interval, because that belongs to the machine manual and the fuel quality at your site. And no cross-reference number for this element: for 509-5694 we could verify two catalogue numbers from independent sources, but for 523-4987 the listings we found were supplier codes rather than catalogue crosses, so we publish none. Send the machine model and serial prefix, the number stamped on the old element if it is legible, and the diameter and length, and we confirm the separator, the secondary element and the seals, quote the pair, and ship 3–7 days FOB Shanghai or CIF to your port.

FAQ

Q: What is Cat 523-4987?
A: 523-4987 is the Element-Separator Cat files under Engine Filters > Fuel Water Separators — the element that drops into the water separator housing on Next Gen C4.4 machines. Cat publishes it as a cartridge, flow out-to-in, diameter 4.043 in (102.7 mm), length 10.169 in (258.3 mm), material polyamide plastic, efficiency category Ultra High Efficiency, with Meltblown media and glass-filled nylon end caps. It is not the whole separator assembly: it is the serviceable element inside it.

Q: Do I need 509-5694 as well as 523-4987?
A: On the machines where both numbers appear — a 320 GC, 323 GC or 326 GC, for example — yes. 523-4987 is the upstream separator element and 509-5694 is the downstream secondary fuel filter element, and they are different sizes: 102.7 mm × 258.3 mm against 88.5 mm × 169 mm. Cat's product copy for the separator line states that fuel water separators are built to extend the life of the secondary filter, which is the order they sit in. Check the machine's parts book, because Cat's lists for the two numbers are not identical.

Q: Which machines does Cat 523-4987 fit?
A: Cat's published compatible-model list runs wider than the secondary element's: excavators 316 GC, 320, 320 GC, 320 GX, 323, 323 GC, 323 GX, 325, 326, 326 GC, 330, 330 GC, 333, 333 GC, 335, 336, 336 GC, 340, 345, 345 GC, 350 and the forestry excavators FM538, FM548, FM558, FM568; wheeled excavators M314, M315, M315 GC, M316, M317, M318, M320, M320 GC, M322, MH3026, MH3040; material handlers MH3022, MH3024, MH3032, MH3040, MH3050, MH3250; wheel loaders 926, 930, 938, 950, 962; motor graders 120 GC, 140, 140 GC; mobile hydraulic power units 330 MHPU, 336MHPU, 340MHPU; forestry 538, 548, 558, 568, FM528, FM528 LL; and the C4.4 industrial engine.

Q: What length is 523-4987 — 250 mm or 258 mm?
A: Cat prints both figures on the same page. The specification sheet gives Length 10.169 in, which is 258.3 mm; the attribute line in the description block gives 250.3 mm (9.85 in). That is an 8 mm spread inside one Cat page, so we quote both rather than pick one. If two suppliers are quoting a 250 mm and a 258 mm element, measure the old one — the diameter is agreed at 4.043 in (102.7 mm).