Crankshafts are super crucial for car engines. They turn the back-forth motion of the pistons into a round-and-round motion that makes the wheels spin. But sometimes, crankshafts can break for many reasons – they get too worn out, don’t have enough oil, get too hot, are not aligned right, or get hit.
In this blog post, we will discuss why crankshafts break, how to identify if they need replacement, and how to repair them.
What Causes Crankshaft Damage?
Crankshaft damage can occur because of the following factors:
- Excessive wear: Over time, the crankshaft and its bearings can wear out due to friction, resulting in reduced performance, noise, and vibration. You can prevent this by using the correct oil grade, changing the oil regularly, and not overloading the engine.
- Improper lubrication: Lack of sufficient or poor quality oil can lead to insufficient lubrication of the crankshaft and its bearings, causing them to overheat and seize. Regularly checking the oil level and quality and adhering to the manufacturer’s recommended intervals and specifications can prevent this.
- Overheating: High temperatures can cause the crankshaft and its bearings to expand and deform, leading to cracks, warping, or bending. This problem may arise from insufficient cooling, low oil pressure, or faulty sensors. The problem can be prevented by maintaining the cooling system, ensuring adequate oil pressure, and replacing faulty sensors as soon as possible.
- Misalignment: The crankshaft and its bearings must be appropriately aligned to ensure smooth operation and prevent excessive stress. Misalignment can occur due to improper installation, faulty components, or engine damage. Fortunately, this can be corrected using appropriate tools and techniques, replacing defective components, and repairing engine damage.
- Impact: Worn ball bearings or crankshafts can also suffer damage from sudden or severe effects, such as hitting a curb, a pothole, or another vehicle. It’s important to drive carefully, avoid obstacles, and wear seat belts to prevent loss of power, noise, and vibration. The crankshaft breaking, bending, or twisting can cause these problems.
How to Realize that Crankshaft is Damaged?
Crankshaft damage can show up in different ways depending on the type and severity of the damage. Some common symptoms of crankshaft damage are:
- Loss of power: If the engine’s crankshaft is damaged, it may not be able to deliver the required energy and speed to the wheels, leading to decreased acceleration, performance, and fuel efficiency. A dynamometer can detect engine problems by measuring power output.
- Noise: If you hear strange sounds from your engine, it may be due to a damaged or misaligned crankshaft or bearings. You may hear noises like rattling, knocking, squeaking, or grinding. The sounds may vary in frequency and loudness depending on the engine load and speed. You can use a stethoscope to amplify the engine sounds and detect unusual noises.
- Vibration: If there’s something wrong with the part of the car that helps the engine work smoothly, called the crankshaft or its bearings, it can make the car shake a lot. In addition to making driving uncomfortable, it can also affect the car’s stability. You might feel the steering wheel, pedals, or seats shaking. If you want to be sure, you can use a vibration analyzer to see how much the car is shocking and how fast it’s happening.
- Oil leakage: If the engine’s crankshaft or bearings are damaged, it can result in oil leakage. In this case, oil pressure will be low, the engine will overheat, and the lubrication system will not function properly. You can see the oil leakage under the vehicle, engine, or dipstick. To detect oil leakage, you can use a pressure gauge that monitors the engine’s oil pressure.
Can the Crankshaft be Repaired?
The answer to this question depends on the type and extent of the crankshaft damage. Some kinds of crankshaft damage, such as minor wear, misalignment, or cracks, can be repaired by using various methods, such as:
- Grinding: When a crankshaft surface has slight wear, cracks, or warping, you can repair it by scratching the surface with a particular machine. This process removes a thin layer of metal and restores the original shape and size of the crankshaft.
- Polishing: Polishing the surface of a crankshaft is done using a particular machine to make it smoother and shinier. This process helps to reduce friction, allowing the engine to run better. If the crankshaft has any minor scratches, marks, or rust damage, polishing can help to repair it.
- Straightening: A hydraulic press is used to apply heat and pressure to the part to fix any minor bending or misalignment of the crankshaft. Doing so corrects its alignment and reduces any twisting that might have occurred.
- Welding: Sometimes, when a machine or vehicle works a lot, the metal inside can get damaged and crack or break. A particular machine called a welding machine is used to join the broken pieces back together. This way, the machine can keep working like it should without needing to be replaced. Welding can fix small cracks or breaks in the metal.
However, some types of crankshaft damage, such as severe wear, misalignment, cracks, or breaks, may not be repairable or may not be worth repairing due to the high cost, time, and risk involved. In such cases, the only option may be to replace the crankshaft with a new or refurbished one.
Costs of Crankshaft Repair:
- Crank grinding/polishing – $500-1000+
- Central/connecting rod bearings – $150+
- Straightening bent crank – $300-600
- Remanufactured crankshaft – $800-2000+
- Gasket set replacement – $150+
- Labor for disassembly/reassembly – 5-20 hours x shop rate
- Total typical costs – $1000-4000+
Suppose you suspect that the crankshaft of your vehicle is damaged. In that case, it is essential to understand that the specific repair solution and the associated costs will depend on the underlying cause and the severity of the damage.
A mechanic with professional training should conduct the diagnosis, as they can accurately assess the extent of the damage and recommend the most appropriate course of action. Attempting to diagnose or repair the damage without the necessary expertise can lead to further damage to the engine and result in additional, more expensive repairs. Therefore, seeking a professional diagnosis before undertaking any significant engine work is best.
Comparison Studies: OEM vs Aftermarket Crankshaft Performance
| Consideration | Crankshaft Rebuilding | Crankshaft Replacement (OEM/Quality Aftermarket) |
| Cost | Generally less expensive than purchasing a brand-new replacement. Repairs average around $270. | Generally more expensive upfront, potentially costing $3,000 or more. |
| Damage Severity | Viable when damage is minor, such as limited journal wear, and the core material is sound. | Necessary for catastrophic damage, such as deep cracks, significant warping, or if the crank has already been rebuilt multiple times. |
| Process | Involves grinding the journals to remove wear (requiring undersized bearings), polishing, and balancing. Welding may be used to build up severely worn areas. | Removal of the old part and installation of a new one, ensuring bearing clearances are checked to manufacturer specifications. |
| Reliability | Quality depends heavily on the expertise of the machine shop; a poorly rebuilt crankshaft can lead to premature failure. | Offers a fresh start and the expected lifespan of a new component, providing greater long-term reliability. |
| Part Quality | When replacing, OEM (Original Equipment Manufacturer) crankshafts offer guaranteed fit and quality. Aftermarket options are viable if they meet or exceed OEM specifications to ensure long-term reliability. | – |
Certifications for Engine Repair
To achieve an understanding of automotive diagnostics, you may need to obtain certification from a security institute in Dubai such as ASTI Academy, which offers programs on automotive diagnostics and automobile engineering. An automotive technician will learn how to work on today’s vehicles, including electric and ADAS systems, widely found in the UAE. Precision, tolerance, and proper documentation will be the standard for performing engine repairs (crankshaft grinding) because the work that is done should not be considered as DIYs.
Diagnosing and Identifying Crankshaft Failures
Engine bearing failure due to manufacturing defects has occurred with Hyundai’s and Kia’s Theta II engines. The result has resulted in major class action lawsuits in the United States due to severe engine damage, as well as the excessive buildup of metal debris. The failure was triggered by a variety of conditions, including inadequate lubrication, fatigue cracks, excessive loading, corrosion, and improper installation. Diagnosing the failure begins with knocking or knocking sounds coming from the engine, followed by finding metal debris in the engine oil, and continuing with finding low-pressure readings during engine operation. Finally, laboratory analysis of the engine oil will be performed to detect wear metal content and non-destructive testing methods (NDT) such as magnetic particle testing.
Methods of Inspection
Crankshafts that need inspection by professionals are inspected utilizing two devices. The first device, dial indicator, is utilized in conjunction with V-blocks to determine amounts of run out and warpage. The second device, micrometer, is used to measure journal dimensions. Laser alignment tools are another method of inspecting crankshaft alignment. Initially checked via visual and/or acoustic signs from the engine, such as a repetitive thud sound, the use of a dye penetrant will verify any cracks at fillets through non-destructive testing procedures. It is through these procedures that the technician makes an informed decision regarding whether to repair or replace the crankshaft based on its overall safety and performance capabilities.
Repair and/or Replacement
If the crankshaft has been damaged and is unable to be fixed, the technician will most likely advise the customer to repair the damaged crankshaft before replacing it. The type of repairs performed and whether or not the crankshaft can be repaired will depend on the type of wear that has occurred. For minor wear, crankshaft repairs may cost approximately $270; however, a crankshaft repair requires a professional shop to do the work correctly, along with the ability to grind, polish, and balance the crankshaft utilizing undersized bearings. For severe damage, such as cracks or warping, a crankshaft replacement would cost between $1,500 and $3,000 or more for replacement with OEM parts (parts made by the original equipment manufacturer) that would guarantee proper fitment. In contrast, a reputable aftermarket company will produce crankshaft parts that will be built to specifications; customer preference for OEM/aftermarket replacement parts is based on factors, such as age of motor, amount of money, and intended use.
Maintenance for Longevity
In addition to inspection and/or repair/replacement of the crankshaft, a quality maintenance program for the crankshaft is recommended for long-term durability. A technician should perform routine oil analysis to check the journal finish and oil contamination and look for any trends from sampling several draws from the same engine; the technician should then recommend proper steps to prevent issues associated with degradation of oil. The technician must maintain the proper journal finish (≤ 10 microinches Ra) and keep the clearances between the journals (0.0005 inches–0.001 inches) tight enough to maintain a sufficient lubrication film during Gulf stresses. Finally, in addition to the technician’s recommendations regarding inspection/repair/replacement of the crankshaft, Arsintrading provides additional quality components and recommendations that will help aquify the way that customers correctly care for and prolong the longevity of crankshafts.
Conclusion
Crankshaft damage can significantly affect your vehicle’s performance, safety, and durability. The crankshaft is a crucial part of the engine that converts the up and down movement of the pistons into rotational motion, which powers the wheels. Any harm to the crankshaft can lead to severe engine issues, including low power, poor fuel efficiency, and engine failure.
There are several reasons why crankshaft damage can occur, such as high mileage, poor maintenance, lack of lubrication, overheating, and manufacturing defects. If you notice any unusual noises, vibrations, or oil leaks coming from the engine, it could be a sign of crankshaft damage. In such cases, you should have your vehicle inspected by a qualified mechanic who can diagnose the issue properly.
Depending on the extent of the damage, the crankshaft may be repaired or replaced. Minor damage, such as scratches or nicks on the surface, can be rectified through grinding or polishing. However, a replacement may be necessary if the damage is severe, such as cracks, fractures, or bending. In any case, it is crucial to perform the repair or replacement by a certified mechanic with the expertise and equipment to handle the job correctly.
Following the manufacturer’s recommended maintenance schedule, including regular oil changes, filter replacements, and inspections, is essential to prevent crankshaft damage. It is also crucial to address any engine problems promptly and avoid driving your vehicle under extreme conditions, such as high speeds or heavy loads.
By taking proper care of your vehicle and staying alert to any signs of crankshaft damage, you can avoid costly repairs, ensure optimal engine performance, and extend the lifespan of your car.
People also asked about the crankshaft! [quick answers only]
When the crankshaft is damaged, people also ask the following questions,
What usually causes my crankshaft to fail?
Most crank failures originate from oil starvation, bearing failure, connecting rod failure, or severe overheating issues. Lack of maintenance is often a contributor.
How urgent is it to deal with my damaged crank?
It requires prompt attention as continued use can quickly worsen the damage. You risk complete breakdown or further engine damage by ignoring crank issues.
What are early signs of crankshaft problems?
Early signs include increased engine noise on startup or acceleration, vibration felt at higher RPMs, oil leaks from front/rear seals and gaskets, and oil-burning smells.
Can a bent crankshaft be repaired, or does it need replacement?
Special repair techniques can often straighten and save slightly bent cranks. But severely bent or twisted cranks typically require replacement.
Does crank repair require other engine parts to be replaced as well?
Connecting rods may be damaged, too, and bearings often need replacement. It’s wise to replace seals/gaskets while open and check pistons, cylinders, etc.
Is it expensive to fix a crankshaft?
Repairs can cost anywhere from $500 to over $2,000 or more in some cases. Simple fixes like grinding or polishing are usually less expensive. But it will be the most costly option if you need a total replacement along with machine shop work.
What can I do to prevent crankshaft damage?
Regular oil changes, not ignoring leaks/noises/vibration issues, avoiding overheating and over-revving. Quality parts and proper clearances in bearings are also important.
What causes crankshaft damage?
Excessive wear from friction, improper lubrication causing overheating, overheating from poor cooling, misalignment during installation, and impacts like hitting potholes cause crankshaft damage.
What causes a crankshaft to break?
Overloading beyond limits, torsional vibrations in diesel engines, abnormal combustion like pre-ignition or detonation, and corrosion weaken the metal leading to breaks.
Crankshaft failure often stems from bearing wear, insufficient lubrication, dynamic imbalance, or manufacturing defects as seen in some Hyundai and Kia Theta II engines.
What causes the crankshaft to break?
Axis deviation in main journals destroys balance, excessive cold play, and mechanical overload from jamming create inertial forces that fracture it.
Causes of crankshaft breaking include fatigue cracks from repetitive stress, poor oil flow exposing metal to contaminants, and high-pressure waves from detonation.
Does crankshaft breaks cause ties to sudden overloads?
Yes, Crankshaft breaks cause ties to sudden overloads, like gearbox faults, combined with low lubrication allowing metal-on-metal contact.
What causes crankshaft bearings to go bad?
Lack of lubrication, excessive heat without cooling, contamination from dirt or acid in oil, and incorrect clearances cause bearings to etch, scratch, or seize.
What is the main common reason for Kia crankshaft issues in Theta II engines?
Kia crankshaft issues in Theta II engines involve rod bearing failures from machining debris, clogged oil journals, and metal buildup leading to overheating.
What are the damaged crankshaft symptoms?
Damaged crankshaft symptoms include power loss, knocking or grinding noises, vibrations through steering or seats, and oil leaks with low pressure.
What are bent crankshaft symptoms?
Bent crankshaft symptoms feature uneven bearing wear patterns, especially at the center, increased end play, and low-frequency rumbles that worsen with RPM.
What are the most important signs of crankshaft failure?
Signs of crankshaft failure are deep rod knocks under load, metallic glitter in oil, flickering oil pressure lights, and engine seizure in advanced cases.
How to know if the crankshaft is bad?
To know if the crankshaft is bad, you must check for repetitive thud sounds, low oil pressure readings, metal debris via oil analysis, and runout with dial indicators on V-blocks.
What are the signs of crankshaft loud knocks?
Signs of a bad crankshaft are loud knocks varying with load, rising oil temps, and vibrations increasing with speed.
What are bad crankshaft bearing symptoms?
Bad crankshaft bearing symptoms consist of low hot-idle oil pressure, glittery particles in filters, growls at idle, and clutch noises from thrust wear.
What happens if the crankshaft fails?
if the crankshaft fails it would trigger total engine stall, potential stalling in motion, and debris contamination requiring full rebuild or replacement.
