Crankshaft Bearing Failure
Crankshaft bearing failure is a common issue that can lead to significant damage to an engine. In this blog post, we’ll explore a real-life case study of crankshaft-bearing failure to understand the causes, consequences, and remedies.
In this case, we’ll look at a Marine engine that had been serviced regularly and well-maintained. Despite this, the Generator experienced a catastrophic engine failure caused by a crankshaft bearing failure. We’ll examine the symptoms that led up to the failure, as well as the root cause of the issue.
By analyzing this case study, we can learn how to identify the warning signs of crankshaft bearing failure and how to prevent it from happening in the future. Whether you’re a mechanic or a car owner, this post will provide valuable insights into how to protect your engine and ensure its longevity.
What Happens when Bearing fails?
The shift Engineer had observed Heavy smoke from the Breather line followed by obnoxious noise from the Engine. He immediately stopped the Engine and opened up the Crankcase doors after about 15 minutes for inspection to assess crankshaft bearing failure. Upon opening up the doors following damages were observed.
- Conrod bearing # 6 was found roBearing of connecting rod no. 6 was found damaged due to rotation with the crankpin in the housing.
- The flow of White metal was seen from the Conrod big-end collars.
Unit # 6 was pulled out from the position and further inspection revealed the following.
- Both the bearing shell halves were found rotated in the housing.
- Bearing metal up to the steel backing was found rolled out and thinned up.
- The white metal has got stitched with the crank pin.
- Conrod big end serrations were found damaged.
- Symptoms of Big end bore overheating have been observed.
- Small end bush has also suffered metal flaking in the 1” area.
- Connecting rod bolts were having the symptoms of overheating and were suspected to be elongated.
- The cylinder Liner was pulled out and vertical seizure marks were observed
NDT test report
To investigate the crankshaft bearing failure damaged/affected area on Crankshaft NDT for superficial cracks, internal cracks and Hardness affected part was subjected to NDT test and the following results were recorded.
- DP test- NRD
- MPT- NRD
- Hardness test
Opinion & Adv
Jobs to be carried out
- White metal to be removed from the crankpin and to be polished properly.
- Crankpin is to be subjected to MPT, UST & Hardness test
- Crank deflection is to be checked.
- Neighbourhood unit to be inspected for any damage.
- Crankpin is to be checked for taper and ovality
What causes crankshaft failure?
I was contacted by a client to attend to this Engine that had suffered crankshaft bearing failure from overheating on its MAN/B&WL23/30 H type Engine.
During the inspection we observed a connecting rod big end bore enlarged and the reason was cam wear of crankshaft pin caused overheating of the bearing. Deep scratches were developed and crankpin surfaces were damaged.
This has also caused Distortion of CR big-end bore, cracks in the journal surface as well as damaged fillet radii.
Our technicians performed local grinding to determine the depth of the cracks and hardness testing to determine whether or not the hardness levels were acceptable.
The important task was to find the extent of the damage to the crankpins and to the main journals. We calibrated and tested the following.
Measurement of Maximum and minimum diameters taper and wear of damaged crankpin.
2) Connecting rod bores for dimensions and wear.
3) The run out of adjacent main journal to check for heat induced bents in the crankshaft.
4) Amount of cam wears in each of the crank pins.
5) To carry out the non-destructive testing on all the crankpins including the damaged pin, using magnetic particles and ultrasonic for heat cracks both on the surface and the sub surface of the damaged crankpin.
Measured Hardness readings are produced below.
| Position | Reading/BHN |
| Free end fillet Radius | 265 |
| Deive end filltet | 292 |
| Center TDC | 518 |
| Center BDC | 536 |
| Pump Side | 576 |
| Rear Side | 624 |
| 10 mm Away from Rear side | 578 |
Recommended Hardness Value= 225 to 265 BHN (crankshaft bearing failure)
Comprehensive testing and profiling of hard spots and bands on the damaged crankpin.
7) Conditions of the existing bearings.
The crank pin was finish machined to a diameter of (- 1.0 mm) well within maker limits.
After our tests, we decided
a) Crankpin # 6 must be ground 1mm undersize to remove hard spots and heat cracks.
b) All main journals must be inspected & polished to remove surface scratches.
c) The bent Crankshaft at main journals # 6 and 7 and had to be straightened.
The investigation findings were useful since we could get the re-usability of significant components like the Crankshaft and the period required for the entire repair.
Knowing this, the service team could and did schedule other maintenance that Hass was carried out at the same time.
With the gathered information we could identify the spares, well ahead of time correctly, that would be required for reassembly and re-commissioning of the engine..
The Crankshaft had suffered a heat-induced bent due to crankshaft bearing failureat the main journals # 6 and #7. The stress relieving was achieved by using a peening hammer on the heat-affected crankpin # 6. After this stage of the repair, the run-out of the Crankshaft was restored to 0.025mm, which was precisely at Builder’s Specifications.
Crankpins #6 was ground to the specification sizes. Work was carried out on 16 hours basis using one grinding turbine to speed up the repairs.
While grinding was in progress, removed the cylinder liners, Servicing of Cylinder heads was performed.
In house quality control system requires that Monitored these grinding repairs daily with the following checks:
1) All micrometers were calibrated using “Standard” bars.
2) Presence and conditions of heat cracks checked by Magnetic Particle Inspection technique
3) Carried out the Hardness testing using handheld portable electronic testers to determine the degree of existing hardness and the sizes of affected areas.
Grounded The fillets adjacent to the bearing landing surfaces achieve a smooth transition to the webs and provide a good oil flow for the cooling lubrication oil.
Finally, the crankpin was polished with an oscillating superfinishing machine to obtain a finish of 6 micro-inches.
Inspected all the main journals, and scratches were polished.
After careful cleaning, the engine was rebuilt using a new bearing with 1mm downsize. Tested the engine and opened the bearing d to determine the contact pattern.
TOLERANCE ACHIEVED
- The crankshaft was straightened to 0.03mm.
- The ovalty and taper of the reground crankpins was a maximum of 0.03mm
- The reground crankpin was held to 0.05mm for the parallelism
- Restored the hardness of the reground crankpin to 250 Hardness Brinell except at one spot o 500 Hardness Brinell.
Removed all heat cracks
CRANKSHAFT ANNEALING AND MACHINING REPAIRS
Machining of new fillet radii
· Magnaflux crack testing and Hardness testing
· Local grinding to determine the crack depth
· Removal of cracks by rough machining before heat treatment
· Removal of crankpin journal hardness by annealing process.
· Finish machining to (– 1.00 mm undersize)
TIMING ( Job Completion)
I, along with my Service Manager, arrived at the site within 2 hours of the accident. We went ahead for the investigation for Crankshaft & Bearing failure analysis
Inspection and complete testing and calibration took one day.
The work for the critical Repairs continued on a 24 hours basis
It took almost three days for the Grinding of #6 crankpin, including fillet regrind and super finishing. Super finishing /Polishing of each main journal & crankpins took us 4 hours each.
SPARE PARTS CONSUMED (crankshaft bearing failure)
| Sr. No. | Part Description | Qty |
| 1 | Connecting Rod | 01 |
| 2 | Cylinder Liner | 01 |
| 3 | Piston Pin | 01 |
| 4 | Piston | 01 |
| 5 | Sealing Ring | 01 |
| 6 | O ring | 02 |
| 7 | Flame Ring | 02 |
| 8 | Gasket | 02 |
| 9 | Packing | 04 |
| 10 | Packing Oval | 04 |
| 11 | Small End Bush | 02 |
| 12 | Connecting Rid Bearing (-1.00D) | 01 |
| 13 | Main Bearing | 01 |
All the pistons were dismounted and dismantled. After cleaning and checking we have observed that following small end Bushes were damaged.
Cylinder unit no.1 Con Rod, IMO – 0802, 0
Connecting rod of Cylinder no.1
Cylinder unit no.2 Con Rod, IMO – 0802, 00.07.13,
Measurement of connecting rod was carried out and readings recorded are as under.
| Con. Rod | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Sr. No | 110 K | 88 K | 144 K | 11 M (new) | 143 K | 150 K | ||
| A | 195.060 | 195.075 | 195.060 | 195.060 | 195.060 | 195.070 | 195.055 | 195.060 |
| B | 195.085 | 195.085 | 195.070 | 195.075 | 195.085 | 195.060 | 195.070 | 195.055 |
| C | 195.085 | 195.085 | 195.070 | 195.080 | 195.080 | 195.060 | 195.065 | 195.060 |
| D | 195.050 | 195.070 | 195.065 | 195.055 | 195.050 | 195.070 | 195.045 | 195.055 |
| E | 195.045 | 195.070 | 195.065 | 195.050 | 195.050 | 195.090 | 195.050 | 195.050 |
| Ovalness | 0.04 | 0.015 | 0.010 | 0.030 | 0.035 | 0.030 | 0.025 | 0.010 |
One no. connecting rod replaced in the Cylinder Unit no 6 with new one.
Clearance in the small end & piston pin
| Con. Rod | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Sr. No | 110 K | 88 K | 144 K | 11 M (new) | 143 K | 150 K | ||
| A | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | |
| B | 0.20 | 0.20 | 0.15 | 0.15 | 0.10 | 0.10 | 0.10 | |
| C | 0.20 | 0.25 | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | |
| D | 0.20 | 0.20 | 0.15 | 0.15 | 0.10 | 0.10 | 0.10 |
Damages due to bearing failure
We salvaged the crankshaft bearing failure -crankshaft within maker limits. Without the combined grinding and annealing process, this crankshaft would have been condemned and required costly replacement
Failed Parts images
Best Books on Marine Engineering
Fundamentals of Medium/Heavy Duty Diesel Engines
Based on the 2014 National Automotive Technicians Education Foundation (NATEF) Medium/Heavy Truck Tasks Lists and ASE Certification Test Series for truck and bus specialists, Fundamentals of Medium/Heavy Duty Diesel Engines is designed to address these and other international training standards. The text offers comprehensive coverage of every NATEF task with clarity and precision in a concise format that ensures student comprehension and encourages critical thinking. Fundamentals of Medium/Heavy Duty Diesel Engines describes safe and effective diagnostic, repair, and maintenance procedures for today’s medium and heavy vehicle diesel engines, including the most current, relevant, and practical coverage of: • HD-OBD emission diagnostics • Common rail injection systems
Pounder’s Marine Diesel Engines and Gas Turbines
Pounder’s Marine Diesel Engines has served seagoing engineers, students of the Certificates of Competency examinations and the marine engineering industry throughout the world.
Now in its ninth edition, Pounder’s retains the directness of approach and attention to essential detail that characterized its predecessors. There are new chapters on monitoring control and HiMSEN engines as well as information on developments in electronic-controlled fuel injection. It is fully updated to cover new legislation including that on emissions and provides details on enhancing overall efficiency and cutting CO2 emissions.
After experience as a seagoing engineer with the British India Steam Navigation Company, Doug Woodyard held editorial positions with the Institution of Mechanical Engineers and the Institute of Marine Engineer
* Helps engineers to understand the latest changes to marine diesel engineers
* Careful organisation of the new edition enables readers to access the information they require
* Brand new chapters focus on monitoring control systems and HiMSEN engines.
* Over 270 high quality, clearly labelled illustrations and figures to aid understanding and help engineers quickly identify what they need to know.
Lamb’s Questions and Answers on the Marine Diesel Engine
The book is comprehensive and includes almost all topics needed to understand marine diesel engines. The book explains the role of heat in engineering science, the principles behind internal combustion engines, the role of fuels and lubricants, the cooling systems, the lubricating systems and the heat exchangers.
The book also explains the various parts of the marine engines and their functions. Air-storage tanks and air compressors are also dealt with in the book. Information on balancing and vibration, various instrumentation and control methods, along with the safety measures are covered in the book.
Lamb’s Questions and Answers on the Marine Diesel Engine was published by Butterworth-Heinemann in 1990. The eighth revised edition is available in hardcover.
A Pocket Book of Marine Engineering: Questions and Answers
A Pocket Book of Marine Engineering: Questions and Answers is a book that covers the topic of air filter for engine in great detail. This book is a great resource for anyone who wants to learn more about this topic. The author, John Myatt, is a world-renowned expert on marine engineering. In this book, he covers everything from the basics of how these engines work to more advanced topics like choosing the right air filter for your engine. If you’re looking for a comprehensive guide to air filter for engine, this is the book for you.
This handy pocket-sized guide is filled with hundreds of questions and answers on marine engineering, covering all the basics from engines and propulsion to steering and safety. It’s perfect for anyone who wants to learn more about this fascinating subject, whether they’re studying for a qualification or just interested in how boats work. With clear explanations and plenty of diagrams, this book is an essential reference for anyone with an interest in maritime engineering.
Introduction to Marine Engineering
This second edition deals comprehensively with all aspects of a ship’s machinery from propulsion and steering to deck machinery and electrical equipment with a strong emphasis upon correct and safe procedures.
Material has been added and revised to reflect the greater weight now being placed upon the cost-effective operation of ships; in terms of greater equipment reliability, more fuel-efficient engines, the ever-increasing shift towards automatically operated machinery, and the need for fewer engineering crew. This is an invaluable guide for professionals but equally covers the requirements for Class 4 and Class 3 Engineer’s Certificates of Competency, the first two years of the Engineer Cadet Training Scheme, and the Engineering Knowledge syllabus for the Master’s Certificate.
Diesel Generator Handbook
Diesel Generator Handbook meets the need for an authoritative reference work covering the range of mechanical and electrical topics embodied in the practical design and application of diesel generating plant. It will be particularly welcomed in many parts of the developing world where the diesel generator is basic to the electricity supply system.
The discussion covers, in fifteen chapters, the prime mover, power ratings, synchronous generators, load assessment, control principles and systems, switchgear and controlgear, standby power, fuels and lubricating oilss, installation and commissioning, noise reduction, and plant operation and maintenance.
The book thus caters for all who are concerned with the selection, specification, testing, commissioning, operation and maintenance of diesel-based generator systems: not only the practising plant or services engineers, but also non-specialist engineers and users. The young technician or trainee engineer who is embarking on a career in the supply industry will find this handbook an invaluable investment.
L L J Mahon, FIEE, FBIM, after an engineering apprenticeship with BTH in Rugby, gained over 30 years’ experience in the design, development, manufacture, installation and commissioning of both stationary and highly specialised mobile diesel generator plant for a range of applications.
Marine Engineers Tools and working gears
Rechargeable LED Flashlight
The Rechargeable LED Flashlight is the perfect gift for anyone. With its color A LED light, it is perfect for illuminating the darkest places. The powerful beam can easily illuminate the surroundings and can provide you with a farther and clearer vision. The included bulb can provide you with a max of 10,000 lumens, making it the perfect choice for an emergency lighting needs.
Vibration Meter
The Vibration Meter, High Accuracy Split Type Digital Vibration Meter is the perfect tool for measuring vibration levels in the environment. With a wide measurement range of acceleration: 0.1~199.9m/s2 peak, it can measure the environment temperature with 2 temperature units (℃ and ℉). The vibrometer gauge adopts a piezoelectric acceleration transducer to transfer the vibration signal into an electrical signal, analyze the input signals, and show the vibration level.
Blog Conclusion
We hope you enjoyed our blog about Crankshaft bearing failure. We hope that this blog post was able to provide some answers and clarity around Crankshaft bearing failure. Check back often to always get the most current information on Crankshaft bearing failure and be sure to contact us anytime should you have any other questions or concerns.
