What a Crankshaft Does, and Why Failure is Catastrophic
The crankshaft is one of the most mechanically loaded components in any diesel engine. On every combustion cycle, each piston transmits the full force of combustion down through its connecting rod and onto the crankshaft journal at that rod's throw, a force that can exceed several tonnes on a large heavy-duty diesel platform under full load. The crankshaft must absorb this force from every cylinder in rapid sequence, convert it into smooth rotational output, and do so continuously for tens of thousands of operating hours.
To survive these loads, the crankshaft depends on two things above everything else: a constant supply of clean, pressurised engine oil to the main and rod bearing journals, and dimensional integrity across every journal surface it carries. When either of these conditions is compromised, the consequences are rapid and severe:
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Main bearing failure — the most common crankshaft failure mode. Oil starvation or contaminated oil destroys the bearing shells, and direct metal-to-metal contact between the crankshaft journal and the bearing housing follows rapidly
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Journal wear — gradual erosion of the journal surface increases bearing clearance beyond OEM tolerance, reducing oil film pressure and accelerating bearing wear in a self-reinforcing cycle
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Crankshaft cracking — fatigue cracking develops in the fillet radius between the main and rod journals on high-hour engines subjected to repeated overloading or severe bearing knock
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Crankshaft fracture — the terminal failure mode. A fractured crankshaft destroys the engine block, connecting rods, and everything attached to the rotating assembly in the same event
Unlike almost every other component in a diesel engine, crankshaft damage cannot be recovered through in-field repair. When a crankshaft fails, replacement is the only path, and the quality of the replacement determines the service life of the entire engine rebuild that surrounds it.
CAT Crankshafts, Full Platform Coverage
Caterpillar diesel engines are the most widely rebuilt heavy machinery powerplants in the industry, and CAT crankshafts are among the highest-demand rotating assembly components in our range. The 3406 family and the C15 platform together represent the majority of CAT crankshaft demand, reflecting both the volume of these engines in active heavy-duty service and the known main bearing and journal wear characteristics they exhibit at high engine hours.
Our CAT crankshafts range covers:
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CAT C15 & C15 ACERT — the highest-demand CAT crankshaft in our range, precision-ground and balanced to OEM specification for both the standard C15 and ACERT variants
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CAT 3406, 3406E & 3406B — one of the most rebuilt CAT engine families in existence, with exact journal specification matching required between 3406B and 3406E variants
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CAT C16 & C18 — high-output CAT powerplants for the largest excavators and heavy haul applications, with crankshaft specifications matched to the higher torque outputs of these platforms
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CAT C13 — a high-torque mid-range platform deployed across large excavators and heavy plant equipment worldwide
All CAT crankshafts are dispatched with full journal dimension documentation for main and connecting rod bearing selection.
Cummins Crankshafts, N14, ISX & ISX15 Platforms
Cummins diesel engines are deployed across some of the most demanding heavy equipment and over-the-road applications globally. The N14 and ISX family are the highest-demand Cummins platforms in our crankshafts range platforms known for high-hour reliability when correctly maintained, but subject to the same journal wear and main bearing failure modes as any high-cycle diesel engine operating under sustained load.
Our Cummins crankshafts range covers:
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Cummins N14 — a high-torque legacy platform with strong ongoing crankshaft demand across heavy plant and on-highway applications
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Cummins ISX & ISX15 — modern high-output Cummins platforms with precision-ground crankshafts available for complete engine rebuilds
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Cummins LB7 — available on request with engine serial number confirmation
All Cummins crankshafts are ground to OEM journal diameter and supplied with full dimensional documentation for bearing shell selection.
Detroit Diesel Crankshafts, DD15 & Series Platforms
Detroit Diesel engines are trusted in the most demanding on-highway and heavy-duty off-road applications worldwide. The DD15 is the highest-demand Detroit Diesel platform in our crankshafts range, reflecting its widespread deployment across heavy haulage fleets globally and the high-cycle operating profiles these engines run under.
Our Detroit Diesel crankshafts range covers:
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Detroit Diesel DD15 — the most widely replaced Detroit crankshaft in our range, precision-ground and balanced to OEM specification for complete DD15 engine rebuilds
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Other Detroit Diesel platforms — contact our team with your engine serial number to confirm availability for your specific Detroit Diesel variant
All Detroit Diesel crankshafts are dispatched with full journal dimension documentation and worldwide shipping capability.
Signs Your Crankshaft Needs Replacing
Crankshaft wear and damage rarely present without warning. The symptoms develop progressively and are distinct enough that experienced workshop technicians and operators can identify them before the point of catastrophic failure — but the window between early warning signs and terminal engine damage is narrow on a crankshaft issue.
Key warning signs that your crankshaft requires inspection or replacement:
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Deep, rhythmic knocking from the lower engine — a consistent knock timed to engine speed is the most recognisable indicator of main or rod bearing failure
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Sudden severe drop in oil pressure — crankshaft journal wear increases main bearing clearance, which reduces the oil film pressure the bearing depends on for survival
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Metallic particles in the engine oil or oil filter — bearing and journal material appearing in the lubrication system- are a serious and urgent indicator of rotating assembly wear
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Vibration through the engine and mountings — crankshaft balance deterioration from journal wear or damage creates vibration that increases with engine speed
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Visible journal scoring or step wear on measurement — dimensional inspection during an overhaul, revealing journals worn beyond OEM undersize regrind limits, means replacement is required
If any of these symptoms are present, continued operation risks converting a crankshaft replacement into a full engine assembly replacement. Contact Imara Engineering before the situation escalates.
What to Replace at the Same Time as Your Crankshaft
Crankshaft replacement is most effective and most lasting when the components that interface directly with the crankshaft are in the correct serviceable condition at the same time.
At Imara Engineering, we recommend sourcing the following alongside your crankshaft:
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Main and rod bearing shells — always replace with new bearing shells matched to the ground journal dimensions provided with your crankshaft. Reusing old shells on a new crankshaft accelerates re-wear immediately
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Crankshaft front and rear main seals — included in a full engine rebuild kit, these seals must be replaced whenever the crankshaft is removed to prevent oil leaks from the first hours of operation
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Pistons and connecting rods — if the connecting rod journals show significant wear, the connecting rods themselves should be measured for bend and twist before reuse. Our Pistons & Rings range for associated component coverage
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Engine gasket and rebuild kit — a complete rebuild kit is required whenever the engine is stripped to crankshaft level. Check our Gasket Kits and Rebuild Kits range for full CAT and Cummins platform coverage
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Camshaft inspection — whenever the engine is stripped to this depth, the camshaft should be inspected and replaced if lobe wear is present. Check our Camshafts range for full platform coverage
Our team can consolidate all associated components into a single order to eliminate the risk of a missing component halting your rebuild.
Why Source Your Crankshaft from Imara Engineering?
Workshop managers and fleet operators across Australia, North America, Canada, and globally choose Imara Engineering for crankshafts because dimensional precision and documented specification are non-negotiable in the rotating assembly, and we do not compromise on either.
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Precision Ground to OEM Journal Specifications — Main and rod journals ground to OEM diameter tolerances and surface finish specifications. Correct journal geometry is what makes bearing shells last and oil pressure hold.
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Dynamically Balanced to OEM Tolerances — Every crankshaft is balanced to OEM rotational specifications before dispatch to eliminate vibration and uneven bearing load under operating conditions.
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Full Journal Dimension Documentation Included — Every unit is dispatched with complete journal dimension records, giving your workshop the data to select the correct bearing shells before the engine goes onto the stand.
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Confirmed Fitment Before Dispatch — Engine serial number cross-referenced before every order ships. C15 or C15 ACERT, 3406E or 3406B — the correct specification confirmed, not assumed.
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Fast Worldwide Shipping — Dispatching to Australia, USA, Canada, and internationally with full tracking and fast turnaround on all in-stock items.
