4 Symptoms of a Seized Engine, Causes & How to Fix it

Mechanic Turning Engine

Your car engine is a sophisticated component containing many working parts. If something breaks, the whole system can be thrown off-balance, possibly leading to a seized engine. 

A seized engine means that a major part has stopped moving, causing the engine to fail. We look at the symptoms of a seized engine, reasons why it happens and how to fix it. 

Symptoms of a Seized Engine

  1. Engine Doesn’t Start
  2. Physical Defect
  3. Burnt Wires
  4. Engine Noises

Engine Doesn’t Start

Start Engine

When the engine seizes, the car might not start. You should still be able to turn the car on and run the electronics, such as the heater fan, lights and radio.

However, cranking the engine will produce no action. If anything, you will hear a clunking sound when the starter impacts the flywheel. 

Physical Defect

Sometimes the engine seizes because an internal part became loose and lodged itself into another component. If this is something such as a piston connecting rod, it could penetrate through the engine block. 

An inspection of the engine block would reveal the problem because the parts can come through the top in severe cases. 

Burnt Wires

The seized engine itself doesn’t create burnt wires; it’s what happens after the engine fails. As the starter attempts to crank the engine, additional problems occur.

The starter isn’t able to turn the engine, so the wires start overheating. You will notice smoking and a burning smell, which is a common occurrence after a seized engine happens. 

Engine Noises

Shortly before the engine seizes, you might notice some strange engine noises. Sometimes these noises appear as a light tapping, or it can be a faint knocking. 

Either way, the engine is about to fail completely once you hear the dead knock. This sound often accompanies a piston connecting rod hitting the crankshaft. 

Seized Engine Causes

  1. Lack of Engine Oil
  2. Water in the Engine
  3. Rusty Components
  4. Broken Components
  5. Overheated Engine
  6. Locked Starter
  7. Timing Belt/Camshaft Failure

Lack of Engine Oil

Check Engine Oil Level

Your car engine needs oil to maintain proper lubrication of the moving parts. The oil also provides some cooling to the engine components. 

When the engine oil gets too low, the engine begins to heat up and parts start rubbing together. A lot of friction starts to occur as the internal components dry out. The engine can only run like this for so long and will eventually seize.

Water in the Engine

Water isn’t meant to be in the car engine, but sometimes it finds a way in. If you drive though a large puddle, water can makes its way into the intake. 

Other times, water can infiltrate the fuel tank. Because it doesn’t compress like the air/fuel mixture, it causes damage to the connecting rods inside the engine. Once the connecting rods bend, the engine seizes. This situation is otherwise known as Hydrolock

Rusty Components

Over time, metal is prone to rusting. As the vehicle gets old, the chances of rusty parts become higher. 

While internal engine parts don’t generally get rusted with proper lubrication, if water got inside, it could happen. Once parts are rusted, the components grind together, causing metal shavings that could interfere with operation. 

Broken Components

Rust isn’t the only thing that can happen to the moving parts. It’s also possible for components to break. This problem occurs with the valves, connecting rod or pistons. 

If these parts break off, they get stuck somewhere in the engine where they don’t belong. This is the cumulative effect, where one defect led to another. 

Overheated Engine

The engine should never be allowed to overheat, or you are looking at serious problems. First, overheating engines lead to expanding pistons, which can create damage to the cylinder walls.

Aside from this, you can also blow a head gasket when the engine overheats, which is another expensive repair. 

Locked Starter

While a locked starter isn’t going to cause a seized engine, the symptoms are closely related. The two can feel the same. 

When the starter seizes with the solenoid stuck, it grabs the flywheel. Thankfully, this repair is much more manageable than a seized engine. 

Timing Belt/Camshaft Failure

If the timing chain, belt or camshaft fails, it can cause the valves to hit the pistons. As we’ve already looked at, trouble with the pistons causes the engine to seize. 

How to Fix a Seized Engine

Fix Engine

Fixing a seized engine starts with ensuring that’s the problem. Many times, a bad starter resembles the same symptoms, so you want a proper diagnosis first.

By manually rotating the crankshaft, you rule out the starter. However, if it won’t rotate, you want to remove the starter and try again. 

Remove the serpentine belt and try to rotate it again to make sure it is not seized because of a bad alternator or ac compressor.

If you have the knowledge, you should also check the timing belt or timing chain timing.

Once you determine the engine is seized, you don’t have a lot of options for repair. Most of the time, it makes the most sense to replace the engine. Without seeing inside the engine, it’s difficult to know how much damage has been done. 

Sure, there are some internal components that could be repaired with the help of a machine shop, but this can become more expensive than replacing the motor. However, high-performance or rare motors might be better fixed instead of replaced. 

If the engine is seized up because it spent too much time in the elements, you might be able to salvage the engine because there aren’t internal defects. A qualified mechanic can help you determine the right course of action. 

Can a Seized Engine be Rebuilt?

There’s always the option to rebuild a car engine, but labor costs can become astronomical depending on what the problem is. Before getting an estimate, the mechanic will have to pull the engine apart to look for irreparable damage. Mainly, the mechanic won’t want to see a rod through the engine block.

Additionally, if the engine has overheated, it might have warped internal components, thereby degrading the durability. In most cases, it just makes sense to replace the engine. 

Seized Engine Fix Costs

The seized engine repair costs are going to quickly exceed $3,000 whether you choose to replace it or rebuild it. If you have an older vehicle, this expense won’t make sense, which is why many vehicles with a seized engine end up in the junkyard.

Written by: Magnus Sellén

Founder, owner & main author of Mechanic Base. I have been repairing cars for more than 10 years, specialized in advanced diagnostics & troubleshooting. I have also been a drifting driver and mechanic for over 7 years.