Crankshaft
Hidden inside your engine bay, the crankshaft plays a vital role in your car’s engine, but it rarely gets the attention it deserves. While most drivers aren’t familiar with what it does, this hard-working component transforms the up-and-down motion of the pistons into the rotational force that keeps your car’s wheels turning.
The good news? It’s built to last. But like every part of your engine, it depends on routine maintenance and the right oil to stay in peak condition.
At Robert Cockings Motor Repairs, we support drivers in Yeovil, Dorchester, and Taunton with professional servicing that helps protect vital components like the crankshaft. In this guide, we’ll explain what the crankshaft does, how the crankshaft position sensor works, and what signs to look out for if something goes wrong.
Crankshaft Basics Explained
So, what exactly is a crankshaft?
The crankshaft sits low in your engine block and is surrounded by a protective housing called the crankcase. Just beneath it, the oil pan stores the lubricating oil that flows through the crankshaft’s internal passages (known as oilways), helping to reduce friction and keep temperatures under control.
Its main job? To convert the linear (up-and-down) movement of the pistons into rotational motion. This rotation powers everything from your gearbox to key systems like the alternator, air con compressor, and water pump.
To handle this workload, the crankshaft is precision-engineered with:
- Counterweights to reduce vibration
- Oil channels allowing oil to flow freely, keeping surfaces lubricated
- Smooth bearing surfaces for efficient, low-friction movement
Despite its durability, the crankshaft isn’t invincible. Without the right care, it can suffer wear, overheating, or, in extreme cases, catastrophic failure.
The Crankshaft: What It Does
Let’s take a step-by-step look at what the crankshaft actually does inside your engine:
- Fuel ignites in the engine cylinders, forcing the pistons down.
- The pistons are connected to the crankshaft via connecting rods.
- As the pistons move, the crankshaft rotates, changing that motion into rotation
- This is transferred to your transmission, turning your wheels.
- It also drives essential components like the camshaft, which ensures valves open and close in sync, the alternator, water pump, and air conditioning compressor through pulleys.
Put simply, this remarkable piece of engineering transforms the pistons’ up-and-down movements into rotational motion that ultimately powers your wheels. It’s at the centre of everything your engine does.
What Might Go Wrong With Your Crankshaft
The crankshaft is designed to last the life of the engine, but only if it’s correctly looked after. As long as regular oil changes have taken place, damage to the crankshaft is unusual, but if it does occur, it could cause severe damage, requiring rebuilding or replacement.
But in many modern vehicles, it’s not the crankshaft itself that causes issues, it’s the crankshaft position sensor.
Crankshaft Position Sensor
The crankshaft position sensor monitors the speed and position of the crankshaft. It constantly sends this data to the Engine Control Unit (ECU), which uses the information to precisely control ignition timing and fuel injection.
If the sensor fails or becomes unreliable, the ECU can’t accurately fire the spark plugs or deliver the correct amount of fuel, leading to misfires, stalling, or maybe even failure to start.
This is what makes the position sensor an absolutely critical component.
Spot These Signs of a Failing Crankshaft or Position Sensor
When something’s wrong with the crankshaft or its sensor, your vehicle will usually give you clues. Look out for these common symptoms:
- Hard starting – During ignition, the ECU needs accurate crankshaft data. If it doesn’t get a clear signal, the engine may crank but fail to fire. When you get your engine running, the system can estimate the crankshaft’s position using previous data, so problems may not be evident. The real challenge comes later, after you’ve turned off your vehicle and attempt to restart it.
- Engine misfires or poor acceleration – The ECU relies on the crankshaft sensor to manage spark timing and fuel delivery. A failing sensor can cause rough idle, poor acceleration, or noticeable power loss.
- Check engine warning light – An irregular signal or complete sensor failure will often trigger the dashboard warning light. This should never be ignored.
- Temperature-Related Failures – High temperatures affect the crankshaft sensor, sometimes resulting in intermittent issues where the engine stalls and only restarts after cooling down.
- Strange engine noises or vibration – If the crankshaft itself is damaged, you might hear clunks, knocking, or feel unusual vibrations.
These issues can quickly escalate, so if you notice anything unusual, it’s best to have your vehicle checked out. Call us on 01935 427139 and speak to our friendly team; we’re happy to help.
Why Regular Servicing Protects Your Crankshaft
Maintaining your crankshaft isn’t complicated, but it does require consistency. These three steps will go a long way toward preventing problems:
1. Keep Up With Oil Changes
At Robert Cockings Motor Repairs, we follow your vehicle’s recommended oil change schedule. Clean oil is essential for crankshaft health. Iit reduces friction, cools surfaces, and keeps contaminants at bay.
2. Use the Correct Oil
Not all oils perform the same. We only use manufacturer-approved oils to ensure your engine receives the right protection. Using incorrect oil grades can lead to poor lubrication, corrosion and increased bearing wear.
3. Schedule Your Annual Service
This is when our experts carry out full engine health checks, identifying early signs of wear before they become costly repairs.
With the right maintenance, your crankshaft should last the lifetime of your vehicle.
Experience Expert Care for Your Vehicle at Robert Cockings
At Robert Cockings Motor Repairs, we take pride in offering the highest standard of vehicle care. Whether you’re coming in for routine servicing or need expert help with a crankshaft or sensor issue, you’re in safe hands.
We proudly serve drivers across Yeovil, Dorchester, and Taunton, and were recognised as a Top Garage in 2022 thanks to our commitment to quality service and customer satisfaction.
When you choose us, you get:
- A 12-month guarantee on all parts and labour
- Upfront pricing with no hidden extras
- Advanced diagnostic tools and technical expertise
- Genuine or OEM-quality components that meet manufacturer standards
(OEM stands for Original Equipment Manufacturer. When it comes to vehicle parts, this means the parts are made by the same company that produced the original parts for the vehicle manufacturer)
Our team is dedicated to ensuring your safety on the road, no matter where your journey takes you.
📞 Got a question or want to book a service? Call us on 01935 427139 and speak to our friendly team today. From crankshaft inspections to full diagnostics, we’re here to keep your engine in great shape.
