Eight of the seventeen newly approved diesel-engine records in the Sea Keepers catalogue are Caterpillar parts: cylinder liner 126-0739 (SK-00001), band filler 9L-5854 (SK-00005), piston bodies 557-5686 (SK-00006) and 567-1478 (SK-00007-AV), piston and cylinder sleeve assembly 319-6715 (SK-00008), rocker-arm button 258-8721 (SK-00009-AV), camshaft group 243-0551 (SK-00017) and camshaft assembly 242-0673 (SK-00018-AV). Cat engines from the C9, C9.3, C18 and 3456 families are widely used as propulsion and generator engines on workboats, ferries, tugs and offshore support vessels, so this guide explains how to read a Cat reference and what to confirm before the purchase order is raised.
How a Caterpillar part number is built
Modern Cat part numbers use a three-digit prefix, a hyphen and a four-digit suffix, as in 319-6715 or 243-0551. Older references keep a letter in the prefix, as in 9L-5854; both styles remain valid. The number identifies a specific design level, so a part shown as superseded by a newer number must be confirmed through the maker's parts system rather than assumed to be the same item. Record the number exactly as printed, including the hyphen. A transposed digit can resolve to an unrelated part in a different Cat product line, and the error is rarely caught until the box is opened on board.
GP, AS and the words after the name
Cat descriptions carry abbreviations that define the supply scope. AS means assembly: the part is supplied built up with its sub-components, as with camshaft assembly 242-0673 and the piston bodies listed as body as piston. GP means group: a set of parts catalogued together under one number, as with camshaft group 243-0551. A group and an assembly for the same engine position can contain different gears, plugs, bearings or hardware. That is why the two camshaft records, SK-00017 and SK-00018-AV, are kept separate in the catalogue and should never be treated as two names for one part.
Compatible-model lists cover more than the marine engine
Cat builds the same core engine for marine, industrial, generator-set, petroleum and machine applications, and the approved records show this. Camshaft assembly 242-0673 is listed against the C9 marine engine beside C9 generator sets, industrial and truck engines, motor graders, excavators and track-type tractors. Piston body 567-1478 is listed for the C9.3 marine engine, C9.3 generator sets and power modules. Assembly 319-6715 is listed for the C18 marine engine, C18 generator sets and C18 industrial engines. A long compatibility list confirms the engine family; it does not confirm fitment to a particular engine. The serial number does that.
Serial-number prefix and arrangement
Every Cat engine carries a serial number whose prefix identifies the arrangement and build range. Two C18 marine engines with different prefixes can use different liners, pistons or camshafts because of rating, emissions level or cooling arrangement. Send the complete serial number, a nameplate photograph, the rating in kW or bhp and the duty (propulsion, auxiliary or generator) with every enquiry. For a generator set, add the set's own serial number as well as the engine's, because the record for 567-1478 lists generator packages such as the XQ330 separately from the bare C9.3 engine.
Cylinder liner 126-0739 and band filler 9L-5854
The approved cylinder liner SK-00001 is recorded as a Cat engine cylinder liner in grey flake iron, the conventional material for a wear-resistant, well-lubricated bore. Band filler SK-00005, part 9L-5854, is a thin band listed for the 3456 and C18 marine engines, with a recorded size of about 6 by 8 by 0.08 inches. It belongs to the liner installation and should be ordered with the liner and seals for the same cylinder position rather than as a stand-alone item. Confirm the liner's bore, flange height and seal arrangement against the serial-number parts list before release.
Piston bodies 557-5686 and 567-1478, and assembly 319-6715
Cat lists the piston body, meaning crown and skirt, separately from the pin, rings and liner. Piston body 557-5686 (SK-00006) and piston body 567-1478 (SK-00007-AV, recorded in microalloy steel) are bodies only. Assembly 319-6715 (SK-00008) is a piston and cylinder sleeve assembly for the C18 family: the record gives an alloy-steel body with a 72 mm compression height, a 114.98 mm maximum skirt diameter and an overall length of 7.55 inches. When ordering, state whether rings, pin, retainers and seals are required, and whether the maker's service procedure for that serial prefix calls for a complete cylinder pack per position.
Rocker-arm button 258-8721 and camshafts 243-0551 and 242-0673
Rocker-arm button SK-00009-AV is a small low-alloy-steel insert, recorded at about 4 inches long and 0.5 inches high, which carries the rocker load onto the valve stem. Its wear is a symptom of valve-train condition, so inspect the rocker, valve tip and lubrication before ordering buttons alone. Camshaft group 243-0551 (SK-00017) and camshaft assembly 242-0673 (SK-00018-AV, recorded at 37.5 inches long) should be ordered together with the followers, bushes and timing procedure for the engine. The enquiry should state the rotation and the number of cylinders so the correct lobe profile and length are confirmed.
New, remanufactured or used: say which one
Caterpillar supplies many of these components both as new parts and as remanufactured exchange units, while the second-hand market offers take-off parts of unknown history. The three differ in price, warranty and delivery. State the acceptable condition in the request for quotation, ask whether an exchange core is required and request the maker's documentation for each line, so that quotations from different suppliers can be compared on the same basis.
What to send with a Caterpillar parts enquiry
List the engine model and complete serial number, the application (marine propulsion, auxiliary or generator set), the Cat part number copied from the parts book for that serial prefix, the quantity per engine, the condition required, the delivery port and the required-on-board date. Attach nameplate and removed-part photographs. The Sea Keepers RFQ checklist linked below sets out the full format.
Sea Keepers approved Caterpillar records
Each Cat part below has its own approved product page in the Sea Keepers catalogue with the recorded part number, manufacturer, listed compatible models and dimensions where published. Use the pages to confirm the reference you are quoting against, then send the serial-number evidence for a vessel-specific check before the purchase order.
For the business buyer
Confirm the intended vessel or facility, operating environment, quantity and required approval before requesting a quotation. Capacity, coverage and service interval should be matched to the risk rather than selected by headline price.
For technical experts
Verify the delivered model against the maker reference, rating, dimensions, materials, operating limits and certification scope. Record the serial or batch number and retain the manufacturer datasheet, declaration, test report and maintenance instructions in the vessel file.
Product comparison
Compare alternatives on certified performance, compatibility, installation requirements, inspection interval, spares availability and total life-cycle cost. A lower unit price is not a like-for-like comparison when approval documents or service support differ.
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