Your diesel crankshaft in your heavy-duty machinery is a vital piece of equipment within the engine. We’ve previously looked at what a crankcase is and the role it plays in your machinery, but what exactly does a diesel crankshaft do, and what issues should you keep an eye out for?

What is a diesel crankshaft and how does it work?

A diesel crankshaft is a part located within your engine that converts force generated by combustion into rotary motion. It also converts the upwards and downwards motion of the pistons into torque and transmits this to the fly wheel, starting the engine.

Diesel crankshafts are made of forged steel and have a hardened bearing surface. This is because they undergo very high torque loads and cylinder pressure, so need to be hardened and durable. They also have a tough core, and bearing positions are hardened to make them more wear resistant.

A diesel crankshaft also has counter weights in order to balance out the weight of the connecting rods. This ensures an even balance is maintained during rotation.

Signs of diesel crankshaft issues

Diesel crankshafts withstand very high temperatures and pressures, and this can eventually lead to wear and damage.

Here are the top 5 signs of diesel crankshaft issues to look out for:

1. Knocking or tapping noises

If you can hear knocking or tapping coming from within your machinery, the likelihood is that your bearings in your crankshaft are loose or worn. Your crankshaft is moving around and hitting into other parts of the engine, which can often lead to engine failure!

2. Vibration and shaking

When bearings on the crankshaft wear, the stability of the crankshaft is compromised. This makes the engine shake and vibrate, and it can cause stalling or engine failure in more extreme cases.

3. Reduced power

If your diesel crankshaft is damaged, it won’t be able to deliver all of the power generated by the combustion process to the engine. This will be evident through sluggish performance and reduced machine power.

4. Difficulties starting the engine

The crankshaft turns the flywheel which starts the engine. If bearings are damaged along the crankshaft, it will be harder to start the engine and could mean taking multiple attempts to successfully start the engine.

5. Increased exhaust smoke

Your diesel crankshaft also controls fuel injection timing and pressure, so if it’s damaged, fuel won’t be injected optimally. This leads to incomplete combustion and increased exhaust smoke.

Repairing a diesel crankshaft

If your diesel crankshaft fails, you’ll need to decide whether to repair or replace it. Here are some important questions to ask:

1. How hot did the crank get prior to failure? Excessive heat could have made the crankshaft brittle by changing the structure of the metal.
2. Is the crankshaft now bent? If the crankshaft gets excessively hot during a bearing failure, it can bend.
3. Is the hardness of the metal still within the parts’ specifications? Hardness-testing equipment can determine this. If it’s not within specs, the crankshaft is likely too damaged to be fixed.

If there are cracks in the crankshaft, it will need to be welded, but this can be very costly and often it’s more economical to purchase a good quality replacement instead.

Our diesel crankshaft replacements

At Jaytrac, we understand that engines are the heart of your machinery, and we stock a range of engine parts, including high-performance diesel crankshafts, to keep your heavy-duty machinery running smoothly.

Check out our engine parts range, including crankshaft replacements for Cummins, Caterpillar and Komatsu, or get in touch with us on +44 (0) 1604 491133 or sales@jaytrac.co.uk. Alternatively, fill out a contact form and our team will get in touch with you as soon as possible.