Crankshaft Catalog for Cummins Marine & Industrial Engines
Your Complete Source for Aftermarket Crankshafts and Components by Engine Model
Introduction: The Backbone of Cummins Engine Performance
Your Cummins marine or industrial engine is only as strong as its core — and that core revolves around the crankshaft. As the principal rotating element of any internal combustion engine, the crankshaft is responsible for translating the linear force of the pistons into the rotational power that drives your vessel, generator, or heavy-duty equipment. A worn, cracked, or imbalanced crankshaft doesn’t just risk engine failure — it compromises fuel efficiency, increases vibration, and shortens engine lifespan.
At Diesel Pro Power, we provide high-performance aftermarket crankshafts and replacement components for a wide range of Cummins engine models , including B, C, K, L, M, and 855 series configurations. Whether you operate in commercial marine, industrial power generation, or heavy-duty transportation, we deliver the parts you need — fast, accurate, and backed by a 100% quality guarantee.
What Is a Crankshaft and Why Is It So Important?
Core Function of a Crankshaft
The crankshaft is one of the most critical components of in any internal combustion engine, and its role is central to your engine’s ability to operate effectively. In Cummins marine and industrial engines, the crankshaft is responsible for converting the reciprocating motion of the pistons — created during combustion — into rotational torque that powers the vessel’s propeller or a piece of industrial equipment’s drivetrain. Without this transformation of energy, none of the engine’s power could be put to practical use.
But the crankshaft does more than just rotate. It also:
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Transfers power through the flywheel to connected systems such as the marine transmission, alternator, or hydraulic pumps.
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Maintains engine timing by driving the gear train, including the camshaft and sometimes oil or fuel pumps.
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Distributes load and force from combustion evenly across the engine block, minimizing concentrated stress on pistons and rods.
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Stabilizes the engine’s rotation by balancing inertial forces, which is especially important at higher RPMs and under fluctuating load conditions.
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Supports auxiliary operations like starting systems, power take-off (PTO) shafts, and sometimes direct accessory drives.
A well-balanced and correctly fitted crankshaft ensures smooth, quiet operation with minimal vibration. When the crankshaft is compromised — even slightly bent, worn, or imbalanced — it can negatively affect every other part of the engine, including pistons, bearings, seals, and the camshaft.
See other replacement parts for Cummins engines
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Common Signs of Crankshaft Failure
Because the crankshaft is subjected to intense forces during every combustion cycle, it is also a common failure point, especially in older engines, poorly lubricated systems, or units subjected to harsh marine or industrial conditions. Early detection of failure is crucial to avoid catastrophic engine damage.
Some of the most common signs of crankshaft problems include:
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Excessive Engine Vibration
Irregular vibrations, especially under load, often indicate that the crankshaft is out of balance or that bearings are worn. This can cause downstream issues like cracked mounting brackets and fatigued engine mounts. -
Knocking or Rattling Sounds
A deep knocking sound from the engine’s bottom end typically signals a loose crankshaft bearing or damaged journal. Continuing to run the engine can result in a thrown rod or total engine seizure. -
Metal Shavings or Particles in the Oil
Contaminants in the oil, particularly metal filings, often indicate excessive wear on the crankshaft journals or bearings. This is a red flag that internal components are grinding against each other without adequate protection. -
Low Oil Pressure
Worn crankshaft bearings can create larger-than-normal clearances, leading to a drop in oil pressure and poor lubrication throughout the engine. -
Difficulty Starting or Loss of RPMs
If the crankshaft position sensor cannot read proper rotation due to a damaged or misaligned crankshaft, the engine may not start at all or may stall intermittently. -
Misfiring or Timing Issues
Since the crankshaft helps maintain synchronization with the camshaft, any issue with its rotation can disrupt engine timing, causing erratic combustion cycles and misfires.
If you notice any of these symptoms, it’s essential to inspect your crankshaft and related components immediately . Issues can quickly escalate, leading to major engine failure, costly repairs, and extended downtime — especially critical in commercial marine and industrial environments.
How to Identify the Right Crankshaft for Your Cummins Engine
Serial Numbers and Casting Codes
To ensure a correct match, locate your engine’s Engine Serial Number (ESN) — typically stamped on a metal dataplate and contact our team for expert guidance and support.
Cummins Crankshafts by Engine Series
We carry crankshaft assemblies , shell sets , seal kits , gaskets , and accessory components for the most widely used Cummins marine and industrial engines.
B Series Crankshafts (3.9L & 5.9L)
Compatible Engines:
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Cummins 4B 3.9 Crankshaft
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Cummins 4BT 3.9 Crankshaft
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Cummins 4BTA 3.9 Crankshaft
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Cummins 6B 5.9 Crankshaft
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Cummins 6BT 5.9 Crankshaft
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Cummins 6BTA 5.9 Crankshaft
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ISB Crankshaft
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QSB Crankshaft (for marine and industrial variants)
Available Parts:
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New Crankshaft Assemblies
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Main Bearing Shell Sets (Standard and oversize)
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Rear and Front Crankshaft Seals
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Expansion Plug Kits
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Vibration Dampers
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Timing Gear & Crankshaft Gear Sets
These engines are widely used in commercial fishing boats, trawlers, tugboats, backup generators, and mobile equipment. Diesel Pro Power offers crankshaft options that meet or exceed OEM specifications, ensuring long-lasting performance in corrosive saltwater or harsh industrial environments.
C Series Crankshafts (8.3L)
Compatible Engines:
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Cummins 6C 8.3 Crankshaft
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Cummins 6CT 8.3 Crankshaft
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Cummins 6CTA 8.3 Crankshaft
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ISC Crankshaft
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QSC Crankshaft
Available Parts:
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Precision-Machined Crankshafts
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Crankshaft Seal Kits (Rear & Front)
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Crankshaft Gaskets & Thrust Washers
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Main and Rod Bearings
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Gear Cover Gaskets
C-series crankshafts are common in workboats, excavators, construction equipment, and emergency standby generators. We back all C-series crankshaft parts with our quality guarantee, offering worldwide delivery within 24 hours of your order.
855 Series Crankshafts
Compatible Engines:
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Cummins N855 (Small Cam) Crankshaft
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Cummins NTA855 (Big Cam) Crankshaft
Available Parts:
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Standard and Oversize Crankshafts
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Lower Gasket Sets
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Rear and Front Seal Kits
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Standard & Oversize Shell Sets
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Counterweights and Balancers
855 series engines are legendary in high-horsepower applications, from commercial trawlers to industrial mining trucks. Diesel Pro Power’s inventory ensures you get the exact fit for your rebuild, whether you need a factory-standard crankshaft or oversize journals for re-machined blocks.
K Series Crankshafts
Compatible Engines:
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Cummins KTA 19 Crankshaft
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Cummins KTA 38 Crankshaft
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Cummins KTA 50 Crankshaft
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QSK 19 Crankshaft
Available Parts:
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Crankshafts (New and Remanufactured)
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Main Bearing Sets
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Crankshaft Oil Seals
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Gear Cover Gaskets
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End Bearings & Thrust Washers
K Series engines are workhorses in marine propulsion, oil & gas rigs, and offshore generators. Their robust construction means crankshaft replacements require premium precision. We offer only high-grade, tested components that support prolonged heavy-duty operations.
L Series Crankshafts
Compatible Engines:
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Cummins L10 Crankshaft
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Cummins ISL Crankshaft
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Cummins QSL Crankshaft
Available Parts:
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Crankshaft Assemblies
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Seal Kits
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Shell Sets
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Gaskets & Dampers
These engines are often used in industrial applications and stationary power generation. Trust Diesel Pro Power to deliver exact-fit crankshafts and seal kits engineered to keep your system running 24/7.
M Series Crankshafts
Compatible Engines:
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Cummins M11 Crankshaft
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Cummins ISM Crankshaft
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Cummins QSM Crankshaft (Including QSM11 Marine Crankshaft)
Available Parts:
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OEM-Spec Crankshafts
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Crankshaft Seals
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Main and Rod Bearings
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Gasket Sets
The QSM11 is one of the most widely used marine engines today — a preferred choice in everything from yachts to commercial barges. We stock crankshaft components tailored for these high-demand applications.
Why Crankshafts Fail: Top Causes in Marine & Industrial Engines
1. Fatigue and Bending Stress
Repeated cycles of compression and combustion can cause crankshafts to bend, especially if oil pressure is low or loads are high. Eventually, microcracks turn into full fractures.
2. Vibration and Torsional Harmonics
High-speed marine engines can suffer from torsional imbalance if dampers are worn or improperly balanced. This results in resonance damage to the crankshaft.
3. Oil Starvation or Contamination
When oil galleries clog or fail, the crankshaft bearings lose lubrication, increasing friction and heat. This leads to scoring or weld-like seizure.
4. Hydraulic Lock
Common in marine engines, water or fuel ingress into the combustion chamber can cause hydraulic lock — instantly bending connecting rods and stressing the crankshaft beyond its limit.
Diesel Pro Power: What Sets Our Crankshafts Apart
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Premium Aftermarket Quality
All crankshafts are engineered to meet or exceed OEM tolerances, material specifications, and balancing requirements.
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Ready-to-Ship Inventory
Orders placed before 3 p.m. EST ship same day — no delays, no backorders.
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Worldwide Delivery
We ship globally within 24 hours, supporting customers from the U.S. to Latin America, Europe, Southeast Asia, and beyond.
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Warranty-Backed Confidence
Our crankshafts carry a 100% satisfaction guarantee — no questions asked.
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Expert Support
Still unsure? Our experienced team can identify your engine’s configuration and help you select the right crankshaft by part number or application.
Frequently Asked Questions (FAQ)
Q1: How do I know if my crankshaft is damaged?
A: Common signs include excessive engine vibration, knocking sounds, low oil pressure, metal particles in the oil, and difficulty starting. A visual inspection for scoring, cracks, or journal wear is recommended.
Q2: Can I reuse a crankshaft during an overhaul?
A: Only if it passes a full dimensional inspection and meets specifications for runout, taper, and journal diameter. If there’s any pitting, cracking, or severe scoring, replacement is strongly recommended.
Q3: What’s the difference between Small Cam and Big Cam Cummins 855 crankshafts?
A: Big Cam models have a different camshaft drive setup and fuel system timing, which affects the crankshaft gear profile. Always verify compatibility by serial number.
Q4: Do I need to replace bearings when I replace the crankshaft?
A: Yes, main and rod bearings should always be replaced during crankshaft replacement or rebuilds to ensure proper oil clearance and load distribution.
Q5: Do you carry crankshaft bearings for Cummins 6CTA 8.3 engines?
A: Yes. We offer standard and oversize main and rod bearings for the Cummins 6CTA 8.3 crankshaft.
Q6: Are your crankshafts OEM or aftermarket?
A: We sell premium aftermarket crankshafts that meet or exceed OEM specifications for material strength, balancing, and journal finish.
Q7: Can I order from outside the U.S.?
A: Absolutely. We ship worldwide, including to commercial marine operators in Europe, Latin America, Australia, Asia, and the Caribbean.
Q8: What if I don’t see my engine listed?
A: Contact us with your engine’s serial number or model. We may have the part in stock or be able to source it quickly.
Q9: Do you offer crankshafts for Cummins QSM11 engines?
A: Yes. We carry crankshafts, seals, and bearings for the QSM11 marine and industrial engine platforms.
Q10: How soon can I get my crankshaft?
A: Orders placed before 3 p.m. EST usually ship the same day. International shipping options are available with fast delivery.
Q11: Do you sell crankshaft seal kits for Cummins KTA19 engines?
A: Yes. We offer complete seal kits, including front and rear crankshaft seals, for Cummins KTA19 crankshafts.
Q12: Can I get main bearing sets for Cummins 4BT 3.9 engines?
A: Yes. We offer standard and oversize main bearing sets, as well as rod bearings, for the 4BT 3.9 crankshaft.
Q13: What’s included with a new crankshaft assembly?
A: Our assemblies typically include the crankshaft itself and, depending on the engine model, may include keyway gears or pre-installed counterweights. Bearings and seals are sold separately.
Q14: What causes crankshaft failure in marine engines?
A: Common causes include oil starvation, improper bearing clearance, torsional vibration, hydraulic lock, or corrosion from saltwater exposure.
Q15: Do you carry crankshaft bearings for Cummins NTA855 Big Cam engines?
A: Yes. We carry standard and oversize crankshaft bearing sets specifically designed for the Big Cam series.
Q16: Can a crankshaft be repaired instead of replaced?
A: Light scoring can sometimes be polished or reground if journals stay within tolerance. However, severe damage usually requires a full replacement.
Q17: Do you sell crankshafts for Cummins KTA38 engines?
A: Yes. We carry crankshafts and matching bearings for Cummins KTA38 marine and industrial engine configurations.
Q18: What’s the proper way to identify my crankshaft type?
A: Use the engine serial number and casting number on the crankshaft (if available). Contact us if you need help cross-referencing it.
Q19: Do you have crankshaft parts for Cummins QSB 6.7 engines?
A: Yes, we stock crankshafts, main bearings, and oil seals for QSB 6.7 applications used in both marine and industrial platforms.
Q20: What bearing sizes do you carry?
A: We offer standard, 0.010", 0.020", and 0.030" undersize bearings for most Cummins engines. Availability depends on engine model.
Q21: Do you carry crankshaft components for ISC and ISL engines?
A: Yes, we provide crankshafts, bearing sets, and seal kits for Cummins ISC and ISL engines, common in industrial and power generation equipment.
Q22: Are Diesel Pro crankshafts balanced?
A: Yes. Our crankshafts are dynamically balanced to meet OEM-equivalent vibration standards, ensuring smooth operation and extended life.
Q23: Do you carry crankshaft bearings for Cummins ISB 6.7 engines?
A: Yes. We offer high-quality aftermarket bearing sets for the ISB 6.7 engine, a popular choice in marine and vehicle applications.
Q24: Can I buy just the bearings without the crankshaft?
A: Absolutely. All bearing sets are sold separately, and you can order main and rod bearings in the exact size you need.
Q25: Is there technical help available if I’m not sure what I need?
A: Yes. Our customer care team is ready to assist. Provide your engine’s serial number or CPL, and we’ll match the right crankshaft and bearings for you.
Q26: Do you carry crankshaft bearings for Cummins 4B, 4BT, and 4BTA engines?
A: Yes, we carry both main and rod bearing sets for Cummins 4B, 4BT, and 4BTA engines — in standard and oversize options.
Q27: What about crankshaft bearings for Cummins 6B, 6BT, and 6BTA engines?
A: Yes. We offer crankshaft main bearings and connecting rod bearings for all 6B series engines. These are a common wear item during overhauls.
Q28: Can I order crankshaft bearings for ISB and QSB engines?
A: Absolutely. Diesel Pro Power carries crankshaft bearing kits for both ISB and QSB engines used in marine and industrial settings.
Q29: Do you stock crankshaft bearings for Cummins 6C, 6CT, and 6CTA engines?
A: Yes, we have complete main and rod bearing sets for the Cummins 6C, 6CT, and 6CTA 8.3L engines, including standard and undersized sets.
Q30: Can I find crankshaft bearings for the ISC and QSC engine models?
A: Yes, we stock crankshaft bearing kits for both ISC and QSC engines, commonly used in workboats, buses, and industrial power systems.
Q31: Do you carry crankshaft bearings for the L Series Cummins engines like the L10, ISL, and QSL?
A: Yes, we offer crankshaft bearing sets for the entire L Series family, including L10, ISL, and QSL models.
Q32: Are crankshaft bearings available for M11, ISM, and QSM engines?
A: Yes. We stock a full range of crankshaft main and rod bearings for M Series Cummins engines, including both industrial and marine QSM11 variants.
Q33: What about N Series Cummins engines like the NH855, NT855, and N14?
A: Yes. We carry crankshaft bearings for all N Series engines, including NH855 Small Cam, NT855 Big Cam, and N14 models.
Q34: Do you have crankshaft bearings for ISX and QSX engines?
A: Yes. We stock premium-grade crankshaft main and connecting rod bearings for ISX and QSX series engines used in heavy-duty and marine applications.
Q35: Can I buy crankshaft bearings for the K Series — KTA19, KTA38, KTA50, and QSK19?
A: Yes, we carry complete crankshaft bearing sets for all Cummins K Series engines, including KTA19, KTA38, KTA50, and QSK19. These are in stock and ready to ship.
Q36: Are your crankshaft bearings available in oversized options?
A: Yes. For most models, we carry 0.010", 0.020", and 0.030" undersize bearings. Always verify your crankshaft journal size before ordering.
Q37: Are the bearings you sell compatible with both industrial and marine engines?
A: Yes. Our crankshaft bearings are designed to perform in both marine and industrial environments, offering durability and precise oil clearance.
Q38: Do your crankshaft bearings meet OEM specifications?
A: Yes. All of our bearings are premium aftermarket components that meet or exceed OEM specifications in terms of material, performance, and fitment.
Q39: Can I speak with someone to confirm the right bearing size for my engine?
A: Definitely. Our customer support team is experienced with Cummins engines and can help you identify the correct standard or oversize bearings for your application.
Q40: Can I include crankshaft bearings in an engine overhaul kit?
A: Yes. In many cases, crankshaft bearings are included in our complete Cummins overhaul kits, or you can purchase them separately if you're doing a partial rebuild.
Order Your Cummins Crankshaft with Confidence
Don’t wait for your engine to fail. Whether you’re servicing a fleet of marine vessels or maintaining a critical power unit, Diesel Pro Power is your trusted partner for aftermarket crankshafts and components.
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