What Is a Seized Engine and How to Fix It?


Nov 24th, 2021

What Is a Seized Engine and How to Fix It?

Seized engine moments are perhaps some of the lowest points for a driver. What can be more frustrating than finding your car unable to start? The ignition cranks, the fuel tank is full, the spark plugs are new – yet nothing. This behaviour is typical with seized engines. 

What Is a Seized Engine?

Seized engines are a nightmare as it usually means replacing costly parts, or worse, replacing the engine entirely. 

Seized Engine, Meaning

Engines are said to be seized or locked when mechanical failures lock down the crankshaft and prevent it from rotating on the bearings in response to piston movement. 

A crankshaft lockdown is primarily caused by the locking of internal components, such as the piston getting stuck to the cylinder walls, piston rod bearings malfunctioning, and the crankshaft breaking. 

What Causes a Seized Engine?

Here are some of the reasons why an engine becomes seized:

1. Not Enough Engine Lubrication 

Starving your engine of lubricants will cause the engine’s moving parts to start grinding and friction to build up. Friction emits heat, which then causes engine parts to expand. Here’s the domino effect that a simple lack of lubrication causes:

  • The expansion reduces the clearance between the moving parts and may eventually constrict the movement when the pieces start grinding. 
  • The excessive heat may melt and amalgamate or weld the parts together, locking down the engine. 
  • Continued grinding causes the parts to wear out and eventually malfunction and get stuck. For example, the piston head and the cylinder sleeves may wear out, eventually causing the piston to stall.

2. Rust 

When a vehicle is unused for long, rusting of the engine parts may occur. When sensitive parts such as piston sleeves or the piston and crankshaft bearings rust, their movement is restrained, and the engine seizes.

3. Bending of engine parts 

With usage, some of the vehicle parts may bow to pressure. When parts such as the piston rod or the crankshaft crook out of alignment, they can cause jamming and lock the crankshaft.

4. Damaged piston or crankshaft bearings

The bearings play a significant role in facilitating smooth movement of the piston and the crankshaft. When the bearings are damaged, this movement is cramped and may lock down even the entire system, seizing the engine.

5. Broken crankshaft

Though it rarely happens, a crankshaft can develop cracks and eventually break. When it does, a broken crankshaft can jam the pistons against the piston sleeve, stalling the whole engine.

6. Excessive heating in the engine 

Heat may not necessarily come from friction due to lubricant starvation. Sometimes, lack of coolant, continuously overworking the engine beyond its designed capacity, poor carburettor jetting, or poor ignition timing can also cause excessive heating. 

When this happens, the oil will start to overheat, lowering its lubrication properties and eventually leading to metal-to-metal wear that seizes the engine.

7. Accumulation of water in the engine 

Water may accidentally find its way into the engine. Since water is not compressible like gasoline and does not ignite, it causes the engine to seize up.

What Are the Symptoms of a Seized Engine?

Seized engine symptoms appear in two stages: when the engine is on the edge of seizing up and when it eventually seizes. It goes without saying that you should catch the problem in its early stage.

Early Warning Signs

  • A faint knocking or tapping when the engine is running – this sound is produced by the piston rod hitting the crankshaft at the initial stages of the problem. With time, the sound grows into a loud knocking referred to as the 'dead-knock.'
  • The check engine or check oil light on the dash – these indicators should serve as early warning signs, so don’t ignore them.
  • Strange noises when the engine is idling – sounds like there is air leaking at every stroke.
  • Unending grinding sound when you start the engine
  • Excessive consumption of engine oil – you’ll find it’s always low on engine oil when you check.
  • A smell of overheated oil
  • Abnormal violent shaking of the engine – this is commonly experienced from a bent crankshaft.
  • The engine starts performing poorly – a typical symptom when there are leaks past the piston seals.

Signs of a Seized Engine

  • Broken piston rod piercing through the engine block
  • A loud breaking sound commonly experienced when the crankshaft breaks and immediately the engine stops running
  • The engine fails to kick off, even on a full tank with a fully-charged battery and new spark-plugs, while all the other battery-power operated accessories are fully functional. This typically happens when the piston jams inside the cylinder.
  • Finally, the dreaded verdict from the mechanic saying, “It's dead, sir/ma’am.”

How to Fix a Seized Engine

Do not wait for your engine to seize up or start showing signs before you take action. Always check and maintain the required engine oil level and the coolant among other essential engine fluids. Make sure to service your vehicle on time and never miss servicing schedules

If you notice an issue or abnormality with your car, make an appointment to have the vehicle checked the soonest possible time.

If you're lucky and the damage is not significant, your vehicle will immediately kick back into life once you top up the engine oil. 

So, check your engine oil, top it up, and test if the engine will start. You may also need to check the cause of your engine oil level going low. If it’s an oil leak, make sure you get it fixed ASAP. 

Unfortunately for most vehicles, once they start stalling, the damage is usually already severe and requires changing the affected engine parts. Check which affected parts need replacing; it may be worn-out cylinder sleeves, piston rings, piston head, piston rod, bearings, or crankshaft.

Use high-quality parts because you don’t want frequent repeats of this problem. If possible, use genuine or OEM parts. 

If the damage is extensive, especially one affecting the engine block, you may have no other option but to replace the whole engine

Take good care of your vehicle, and it will serve you right. Do not wait until your car is on its knees for you to tend to it. The great thing about it is that you can PREVENT an engine seize up. 

Follow the manufacturer's recommendation on servicing and replace worn-out parts with high-quality manufacturer-recommended parts. 

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