Caterpillar C18 and C32 Cylinder Liner 516-9693: Supersession to 556-0701, Block Matching and Wet-Liner Replacement

The Caterpillar C18 is one of the most widely used high-output diesels in workboats, tugs, offshore support vessels and marine generator sets, and the V12 C32 shares its cylinder dimensions. Both engines use replaceable wet liners, so a worn or cavitated bore is repaired by changing the liner rather than machining the block. The approved Sea Keepers record SK-00043-AV covers Caterpillar cylinder liner 516-9693. An earlier group guide mentioned it in one paragraph; this guide covers the liner on its own, because the supersession and block notes on the record change how it should be ordered.

What SK-00043-AV is

SK-00043-AV is genuine Caterpillar cylinder liner 516-9693 for C18 and C32 engines in industrial, marine and Power Systems generator-set applications. It forms the replaceable wear surface of each cylinder bore in which the piston runs, and it is made of heat-treated high-grade gray iron. The record gives a weight of 5.05 kg (11.13 lb) per liner, which matters when a full set of six for a C18 or twelve for a C32 is being shipped to a vessel.

Three part numbers for one bore: 322-1126, 516-9693 and 556-0701

Caterpillar lists 516-9693 as a service part for liner 322-1126. That means an engine built with 322-1126 can be found in older parts books, service records or a vessel's spares list under that number, while the part supplied over the counter is 516-9693. The record also shows that 516-9693 has itself been superseded by 556-0701, which the Cat Parts Store describes as a cylinder liner with a 165.13 mm outside diameter. In practice a quotation for 516-9693 may come back showing 556-0701. That is normal, but the buyer should ask the supplier to confirm that the newer liner is the direct replacement for the engine serial number, and should keep all three numbers on the purchase order so the receiving engineer can match the box to the request.

The C18 cylinder blocks that use this liner

The record lists 516-9693 in C18 cylinder block assemblies 357-1320, 323-8451, 488-1677 and 517-1978. Block 323-8451 is worth noting: the approved C18 block record SK-00042 (block 301-3018) shows 323-8451 as its likely service replacement. A vessel that has already received a replacement block may therefore have moved from the original block and liner combination to the newer one. The block group 261-0191 behind SK-00042 also lists liner 253-8766, liner seals 155-0809, 155-2793 and 155-0810, filler band 9L-5854 and liner-seat inserts. That shows how many separate lines make up one liner job. Before ordering, read the block part number or the engine serial number and arrangement number, and let the supplier match the liner from those.

Why wet liners are replaced

A wet liner is cooled directly by engine coolant on its outer wall. The usual reasons for renewal are bore wear and ovality beyond the service limit, glazing that causes oil consumption and blow-by, scoring after a piston seizure, and cavitation pitting on the coolant side. Cavitation is the one that is easy to miss: vibration of the liner wall makes small vapour bubbles collapse against the iron, and over time the pits can go through the wall and let coolant into the oil. When a liner is pulled, the coolant side should be inspected as carefully as the bore. Deep pitting on several liners usually points to coolant condition, so the coolant additive level and the cooling system should be checked before the new liners go in.

What to order with the liners

Liners are never fitted with the old seals. Each liner needs new liner seals and, on the C18, a new filler band at the top of the block counterbore. The approved catalogue carries band filler 9L-5854 as SK-00005 for 3456 and C18 marine engines. If the piston has run in a damaged bore, the piston, rings and piston pin should be inspected too, and new rings are fitted to a new liner as a matter of course. On the C18 the head has to come off to pull the liners, so the head gasket and the cylinder head bolts are part of the same job. The approved C18 cylinder head group 312-8590 (SK-00049) and the 12-point head bolt 124-1855 with fastener group 6I-4025 (SK-00048) are both in the catalogue.

Fitting checks

Before a new liner is installed, the block counterbore and the liner seating area must be clean and free of corrosion, because a dirty or pitted seat changes the liner height. Each liner is first fitted dry without seals so that the protrusion above the block deck can be measured and compared with the limit in the Caterpillar service manual. Protrusion is checked at several points around each liner, and the difference between neighbouring liners is checked as well. Only when the readings are correct are the liners removed, fitted with lubricated seals and filler band, and pressed home. The bore is then checked for roundness, because a seal that has rolled or a seat that is not flat can distort the liner. A liner that is too low will not be clamped by the head gasket and can move; one that is too high can crack the flange.

The other Caterpillar liner in the catalogue

Sea Keepers also carries Caterpillar liner 126-0739 in gray iron as SK-00001. It is a different part with a different fitment, so it should not be offered as an alternative to 516-9693 unless the engine data shows that it applies. For general measurement and installation practice that applies to any wet liner, see the marine cylinder liner inspection guide linked below.

What to send with an enquiry

Send the engine model (C18 or C32), the engine serial number and arrangement number, the cylinder block part number if it can be read, the number of liners required, whether a supersession to 556-0701 is acceptable, and whether seals, filler bands, gaskets, head bolts, pistons and rings are needed with the order. Add the delivery port and any documentation the vessel or classification society needs. Sea Keepers will confirm the current Caterpillar number against the serial number and quote the complete liner kit.

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.