Engine Crankshaft: Role, Types, and Maintenance

Crankshaft is an important part of your engine that delivers that converts linear motion into rotational motion to produce torque and movement in your car’s engine.

Understanding the role of the crankshaft and its proper maintenance of it is vital to the smooth operation of the engine

In this article, we’ll take a closer look at the crankshaft, exploring its different parts, types, maintenance, and upgrades.”

What is a crankshaft in a engine?

The crankshaft, a pivotal engine component, seamlessly converts the pistons’ linear motion into rotational motion, crucial for propelling the vehicle forward. Nestled at the engine’s base, the crankshaft harmonizes with the pistons, utilizing their up-and-down movements to create a rotational drive that energizes the vehicle’s wheels.

Crafted typically from cast iron or forged steel, the crankshaft is engineered to withstand substantial stress and pressure, ensuring durable and steadfast performance. It hosts various journals to accommodate connecting rods and bearings, minimizing friction and facilitating smooth rotation.

Additionally, the crankshaft orchestrates the pistons’ firing sequence, maintaining engine balance and stability throughout its operation.

What are the functions of crankshaft?

The crankshaft, a central figure in the engine’s operation, performs a myriad of functions, ensuring the vehicle moves efficiently and reliably. Positioned strategically within the engine, the crankshaft is tasked with several key responsibilities that are vital for the engine’s smooth and effective operation:

• Converting Motion:
  • The crankshaft adeptly transforms the linear (up and down) motion of the pistons into rotational motion, which is essential to drive the vehicle’s wheels.
• Balancing the Engine:
  • It plays a crucial role in balancing the engine by counteracting the vibrations and forces generated during the combustion process, ensuring a smooth and stable operation.
• Driving Additional Components:
  • The crankshaft also drives additional engine and vehicle components, such as the oil pump, air conditioning compressor, and alternator, by providing the necessary rotational motion through belts.
• Managing Piston Firing Order:
  • It ensures the correct firing order of the pistons, maintaining the balance and rhythm of the engine, which is crucial for optimal performance and minimizing vibrations.
• Supporting Connecting Rods:
  • The crankshaft supports the connecting rods, which link it to the pistons, ensuring synchronized movements and facilitating the conversion of motion within the engine.
• Facilitating Oil Lubrication:
  • Through its rotation, the crankshaft also helps in distributing oil to various engine components, ensuring they are adequately lubricated and operate with minimized friction.

In essence, the crankshaft is a multifaceted component, ensuring the engine performs optimally by managing motion conversion, balancing, driving auxiliary components, and facilitating lubrication, thereby standing as a linchpin in the vehicle’s operational efficacy.

What are the different parts of a crankshaft?

The followings are the different parts of a crankshaft and their functions:

Part	Function
Crankpin	Allows the connecting rod to be securely attached to the crankshaft. The cylindrical surface provides rotational force to the large end of the connecting rod.
Main Journals	Bearings attached to the engine block that hold the crankshaft and allow it to rotate inside the engine block. Crank Web Connects the crankshaft to the main bearing journals.
Crank Web	Connects the crankshaft to the main bearing journals.
Counterweights	Provide balance and stability to the crankshaft by applying an opposing force. Mounted on the crank web to eliminate reaction caused by rotation.
Thrust Washers	Prevent the crankshaft from moving lengthwise by maintaining the gap and reducing lateral movement.
Oil Passage and Oil Seals	Allow the oil to flow from the main bearing journals to the big end journals. Oil seals prevent oil from leaking from the front and rear end of the crankshaft.
Flywheel Mounting Flange	Attaches the crankshaft to the flywheel through a flange. The wheel end of the crankshaft has a larger diameter, providing a flange face for mounting the flywheel.

What are the types of crankshafts?

There are three main types of crankshafts: forged, cast, and billet. Let us have a comparison among the three.

Type of Crankshaft	Manufacturing Process	Strength	Durability	Cost	Common Applications
Forged Crankshaft	Heating and shaping steel using hammers and presses	High	Highly durable	Expensive	High-performance engines
Cast Crankshaft	Pouring molten metal into a mold and allowing it to cool and solidify	Low	Less durable than forged crankshafts	Less expensive	Production vehicles, low to medium-performance engines
Billet Crankshaft	Machining a solid piece of material into the desired shape	High	Highly precise and accurate	Expensive	High-performance racing applications

How to care for the crankshaft?

• Regular maintenance: Regular maintenance is essential if you would like to keep the crankshaft in good condition for years. Simple caring methods such as proper lubrication and regular inspection will extend the life span of your crankshaft.

• Upgrades made to the crankshaft: Another way to maintain the crankshaft is to make upgrades such as; the installation of a high-performance crankshaft, the addition of light-weighted components like lighter crankshaft pulleys, the use of high-performance bearings and lubricants that can improve the efficiency and durability of the crankshaft.

What are the signs that indicate a failing crankshaft?

The crankshaft in your car is a reliable durable component. However, it can fail in some instances.

1. Worn Journals

If there is no sufficient oil pressure, the crankshaft journals may come into contact with the bearing surfaces.

This will gradually widen the clearance and reduce the oil pressure.

In the worst case scenario, this can damage the bearings severely, causing significant harm to the engine. If the journals are worn beyond their service limits or are not perfectly round, they must be ground.

2. Fatigue

Constant forces on the crankshaft can cause fatigue fractures, typically found where the journals meet the web.

It is essential to have a smooth radius on this fillet to stop weak spots that can lead to fatigue cracks. The crankshaft can be examined for cracks using magnafluxing.

If you suspect that your crankshaft is failing, it’s important to have your engine inspected by a professional mechanic as soon as possible.

Ignoring the signs of a failing crankshaft can result in further damage to the engine and potentially lead to costly repairs.

What to do if the engine crankshaft fails?

If your engine crankshaft fails, you should take the following steps:

• Stop the Engine: If the engine stalls or fails to start, turn off the ignition and do not attempt to restart the engine. Continuing to run the engine can cause further damage to the crankshaft and other components.

• Call for Assistance:  If the engine has failed while driving, pull over safely and call for assistance. If you are unable to safely move the vehicle, call a tow truck to have it transported to a repair shop.

• Have the Engine Inspected: Take the vehicle to a qualified mechanic or engine specialist to inspect and repair the crankshaft.

• Replace the Crankshaft: In most cases, a failed crankshaft will need to be replaced. This can be a complex and costly repair but is necessary to restore the performance and reliability of the engine.

• Perform Regular Maintenance: Once the crankshaft has been replaced, it’s important to perform regular maintenance and follow the manufacturer’s recommendations to help prevent future failures.

How to fix a failed crankshaft?

Fixing a faulty crankshaft is best left to a professional mechanic, as it requires specialized knowledge and experience. Upon arrival at the repair shop, the mechanic will disassemble the engine to assess the issue. Based on the extent of the damage, repairs may or may not be a cost-effective solution.

If the damage is only caused to the crankshaft

In case the crankshaft has only suffered damage, it may be repairable or need a replacement.

A remanufactured crankshaft can be a more affordable option, while used crankshafts from junkyards may be a viable solution for older cars with high mileage. The mechanic will also check the crankshaft bearings to ensure they are in good condition.

If both the crankshaft and its bearings are damaged

Here, the repair will be more extensive, as the bearings must also be fixed. A new or remanufactured crankshaft and bearings may solve the problem, but if the damage is too severe, a remanufactured engine might be a better option for newer cars. For older vehicles, it may be time to consider sending it to a junkyard.

If the crankshaft, bearings, & the top end of the engine are damaged

 This is the worst type of damage that can occur. In addition to the crankshaft and bearings, the connecting rods and pistons also suffer damage, and if the pistons hit the tops of the cylinders, it can result in serious damage to the valves.

This type of damage calls for a complete engine overhaul, which might require a replacement engine. If the car still holds some value, this might be the best course of action. However, if it is an older car without warranty coverage, it may be more cost-effective to recycle it.

Summary

In the insightful article on CarFinite, the pivotal role, various functions, and integral parts of a crankshaft within an engine are meticulously explored. The crankshaft, a fundamental component, adeptly converts the linear motion of pistons into rotational motion, thereby driving the vehicle’s wheels and ensuring the engine operates with finesse and stability. The article delves into the different types of crankshafts, their manufacturing processes, strengths, and applications, providing a comprehensive guide for automobile enthusiasts and professionals alike. Moreover, it sheds light on the signs of a failing crankshaft and the subsequent steps to take in such scenarios, offering a blend of knowledge and practical advice.

For a deeper dive into maintaining and understanding various car components, explore more valuable insights on the CarFinite Blog.