A crankshaft does not work alone. At the rear it carries the flywheel, which steadies the rotation, carries the starter ring gear and takes the drive to the gearbox or alternator. At the front it carries the vibration damper that protects it from torsional stress and the gear that drives the timing train, the oil pump and the fuel pump, all enclosed by the front housing. When a crankshaft is renewed, or an engine is opened after a starter, timing gear or damper failure, these are the parts that have to be inspected and often replaced with it. Seven records covering them are now in the Sea Keepers approved catalogue for Caterpillar, FPT (Iveco) and Cummins engines. This guide sets out what each record says and how to order correctly.
When a flywheel is replaced
Flywheels are replaced when the starter ring gear teeth are chipped or worn so that the starter pinion skips, when the friction or coupling face is cracked, heat-checked or scored beyond the resurfacing limit, when the bolt holes are damaged or the pilot bore is worn, or when a crankshaft failure has thrown the flywheel out of true. On many engines the ring gear is a shrink-fit ring that can be changed on its own, but where the record is a flywheel assembly it is supplied with the gear already fitted. The flywheel housing size, written as SAE No. 1, 2 or 3, and the tooth count of the ring gear must match the starter and the housing, so these are the first two details to check.
Caterpillar C15, C18, C32 and 3400 series: flywheel assembly 7W-1248
SK-00063-AV is the genuine Caterpillar flywheel assembly 7W-1248, an iron flywheel of 484.4 mm outer diameter supplied with the starter ring gear, weighing about 43.5 kg. It is used in flywheel groups such as 216-7883 for the C15, C18 and C13 generator sets, 269-0310 for the C32 and 230-9099, and it fits 3406B/C/E, 3408 and 3412 engines as well as C18 generator sets from the D450GC to D600GC and SR4/SR4B packages. The Cat parts database shows it superseded by 195-0313, listed at 120 lb, so a current quotation may carry that number. A C18 that needs a flywheel should also be checked for the crankshaft assembly 189-4918 (SK-00030-AV) and the rear seal.
Caterpillar 3176B and C9: flywheel assembly 132-3141
SK-00061-AV is Caterpillar flywheel assembly 132-3141 for the 3176B and C9, about 48.3 kg, used in flywheel group 123-0466 for the C9 with an SAE No. 1 flywheel housing and in group 132-3151 for the 3176B, including XQP300 generator sets. It is superseded by 482-9074, which the Cat Parts Store describes as a 113-tooth engine flywheel at 98.37 lb. Confirm the tooth count against the starter before accepting the newer number.
FPT (Iveco) Vector 8: flywheel 504224510
SK-00062 is the FPT (Iveco) flywheel 504224510 for the Vector 8 V8 diesel, about 57 kg and made in Italy. It is listed for engine codes FVAE2884X*B200, FVAE2884A*B201 and FVQE2883XA205 in marine and off-road applications. On the same engine the approved catalogue carries crankshaft 504022670 (SK-00032) and connecting rod assembly 504087778 (SK-00023-AV), so a full bottom-end rebuild of a Vector 8 can be sourced from one supplier. No supersession was found.
Cummins QSX15 and ISX15: viscous vibration damper 4101884
SK-00053-AV is Cummins viscous vibration damper 4101884, fitted to the front of the crankshaft on the QSX15 from 375 to 665 hp and on the ISX15 and X15. Inside its sealed housing a free ring runs in silicone fluid and absorbs the torsional twist of the crankshaft, which protects the shaft and the gear train. A viscous damper cannot be repaired: it is replaced if the housing is dented, if fluid is leaking, if it has overheated, or as a matter of course after a crankshaft failure, since the old damper may have been damaged by the same event. Vibratech 718041-600 is an aftermarket direct replacement for 4101884, 4026799 and 3680504. The damper should be ordered together with the QSX15 crankshaft assembly 4925762 / 4393462 (SK-00031) whenever the shaft is renewed.
Caterpillar C6.6 and C7.1: crankshaft gear 276-7391
SK-00064-AV is Caterpillar crankshaft gear 276-7391, a 34-tooth helical gear of about 0.7 kg that is pressed onto the crankshaft nose and drives the timing gear train on the C6.6 and C7.1, including the C6.6 DE150E, DE200E0 and XQP150 generator sets. It appears in crankshaft groups 374-6300 and 348-3285 and in crankshaft kit 374-9163. A new C7.1 crankshaft 376-4074 (SK-00035) is normally supplied bare, so the gear has to be ordered with it and pressed on before the shaft is fitted; the same engine's cylinder head 450-9263 (SK-00045-AV) is also an approved record.
Caterpillar C15 and C18: front housing 248-2607
SK-00072 is Caterpillar front housing assembly 248-2607, which closes the front of the C15 and C18 and encloses the timing gear train. It is used in front housing groups 291-4880 for C18 engines with serial prefixes GPT1, DSE1 and SSW1, 453-3674 for C18 engine arrangements 440-6697 and 545-9474, and 248-2609 for the C15, alongside front housing plate 353-9983. The front housing cover assembly 232-3657 (SK-00028) that bolts over it is a separate approved record. A cracked housing, a damaged seal bore or stripped threads are the usual reasons for replacement, and the front crankshaft seal and the gasket set should be ordered at the same time.
Caterpillar 3406E, C15, C16 and C18: engine oil pump 161-4113
SK-00057 is Caterpillar engine oil pump 161-4113, a one-section gear pump of about 9.5 kg that draws oil from the sump and feeds the lubrication system. It is driven from the front gear train, which is why it belongs in this group: when the front housing is off for a gear or damper job, the pump drive gear and the pump clearances should be checked. Cat lists it across about 150 models including 3406B/C/E, 3408, 3456, C15, C16 and C18, and a 3406E Cat Reman alternative is offered. On the C18 marine engine it sits in the same mechanical package as cylinder head group 312-8590 (SK-00049).
Inspection and fitting checklist
Before a flywheel goes on, clean the crankshaft flange, check its face and pilot for runout, and fit the flywheel with new bolts torqued in the sequence and to the figures in the manual; a flywheel assembly should then be dial-gauged for face and bore runout against the limit. A damper is fitted with new bolts to the stated torque and must never be struck or clamped on its housing. A crankshaft gear is checked for backlash with each mating gear once the timing marks are aligned, and the front and rear crankshaft seals are renewed whenever the housing or flywheel is removed. These checks are described in the crankshaft replacement and overhaul planning guides linked below.
What to send with an enquiry
To identify the correct flywheel, damper, gear or housing, send the engine make, model and serial number or arrangement number, the flywheel housing SAE size and ring gear tooth count for a flywheel, the generator or gearbox the engine drives, and the quantity required. Sea Keepers will confirm the current manufacturer number and any supersession, advise which seals, bolts and gaskets to add, and quote delivery to the vessel or site.
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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