Caterpillar Piston Crowns, C18 Cylinder Block and Liner, and Cummins Valve Crosshead: Overhaul Ordering Guide

Five more engine-core parts are now in the Sea Keepers approved catalogue: two Caterpillar piston crowns, a Caterpillar C18 cylinder block, a C18 / C32 cylinder liner and a Cummins valve crosshead. Each record includes supersession and discontinuation notes that change how the part should be ordered. This guide sets out those facts so a superintendent or chief engineer can send a clear enquiry the first time.

Caterpillar C9 piston crown 385-1657

SK-00040-AV is the genuine Caterpillar piston crown 385-1657 for C9 engines, about 1.54 kg, 111.690 mm diameter with a 46.04 mm pin bore. It forms the top of the piston, carries the rings and combustion bowl and takes combustion pressure. It is used in the C9 piston and rod group 265-1400 with a 16.1:1 compression ratio. Applications include C9 generator sets (D250GC, D300GC, XQP300), C9 industrial and petroleum engines and machines such as D6R, D6T and D7R dozers. One supplier lists 265-1401 as an alternate, and Cat Reman references 10R-6013, 10R-8154 and 20R-1750. No formal supersession was found.

Why the compression ratio must match

The 265-1400 group is listed at 16.1:1 compression. C9 engines were built in several ratings, and a crown with a different bowl gives a different compression ratio, which affects starting, smoke and emissions. Confirm the piston group from the engine serial number, and do not mix crowns from different groups in one engine. Where several cylinders are worn, a complete Cat Reman cylinder pack can be quoted as an alternative.

Caterpillar 3500-series crown 133-8383 is discontinued

SK-00041-AV is Caterpillar Crown As-Piston 133-8383 for 3508, 3512 and 3516 engines, about 5.29 kg. It is the upper crown of the two-piece articulated piston and is used in piston and rod group 6I-2861 with piston skirt 125-2782, ring set KM3500RS, piston pin 138-8507 and retainer 8N-7296. Applications include marine propulsion and marine auxiliary 3500 engines, generator sets, locomotives and mining trucks. The Cat Parts Store lists 133-8383 as discontinued and asks buyers to contact a dealer for replacement options; no replacement number was shown in the sources reviewed.

What to do with a discontinued part number

Send the full engine serial number and arrangement number with the request so the current piston group can be identified. Ask whether the crown is still in stock anywhere, whether a newer piston group replaces the whole assembly, or whether a remanufactured crown is acceptable. Because the crown, skirt, pin and rings work as a set, a change of crown can also change the skirt or ring set, so confirm the full list before ordering.

Caterpillar C18 cylinder block 301-3018

SK-00042 is Caterpillar Cylinder Block As 301-3018 (written 3013018 without the dash), about 363 kg (800 lb), for C18 engines including marine, industrial, generator-set and petroleum versions. It houses the cylinder liners, crankshaft and camshaft and is part of cylinder block group 261-0191, which also contains liners 253-8766, liner seals 155-0809, 155-2793 and 155-0810, filler band 9L-5854 and liner-seat inserts. The Cat Parts Store flags 301-3018 as replaced, and one parts index lists 323-8451 Block As.-Cyl as its service part, so 323-8451 is the likely replacement. Confirm that with a Caterpillar dealer before ordering.

Planning a block replacement

A block is normally replaced only after a cracked water jacket, a damaged main bearing bore or a failure that has holed the casting. At 363 kg it needs crating, lifting points and a planned freight route, so lead time matters as much as price. Order liners, liner seals, filler bands and gaskets with the block, and record which original parts will be transferred so nothing is missing at assembly.

Caterpillar C18 / C32 cylinder liner 516-9693

SK-00043-AV is cylinder liner 516-9693, heat-treated high-grade grey iron, 5.05 kg (11.13 lb), for C18 and C32 engines. It is a service part for liner 322-1126 and is used in C18 cylinder block assemblies 357-1320, 323-8451, 488-1677 and 517-1978. It is superseded by 556-0701, which the Cat Parts Store describes as a 165.13 mm outside-diameter liner. When ordering, ask for the current number and confirm that the new liner suits the block; 323-8451 appears both as the likely replacement block and as a block that uses this liner. Always fit new liner seals and filler bands and measure liner protrusion after installation.

Cummins valve crosshead 3086362

SK-00039-AV is Cummins valve crosshead 3086362, about 0.23 kg, for K19, K38, K50, QSK19 and QSK38 engines, including natural-gas GQSK versions. The crosshead sits on a pair of valve stems and transfers rocker-lever force so both valves open together. One supplier lists 3033687 and 3048620 as related OEM references, and another supplies it as M-3086362 (alternate M-3801445). No supersession notice was found. Check the crosshead pad and guide bore for wear during every valve adjustment, and set the crosshead before setting valve lash, because a misadjusted crosshead opens one valve late.

Send a complete enquiry

List the engine make, model, full serial number and arrangement or CPL number, the part numbers you hold, the Sea Keepers codes, quantities per engine, whether superseded or remanufactured parts are acceptable, documentation needs and the delivery port. The approved product pages and related guides below give the catalogue details and wider overhaul context.

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.