Why Engine Won’t Turn Over by Hand? 7 Tricky Reasons Exposed With Easy Fix!

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engine won't turn over by hand

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Sudden engine stop – a real frustration! But what’s even more frustrating is when you try to start it by hand, and it doesn’t work. This is a common problem that many car owners face at some point.

The engine won’t turn over by hand, which means that the engine is locked up and cannot rotate. This can happen due to various reasons, such as a defective starter, a faulty ignition switch, bad wiring, or an engine mechanical problem.

If you are having trouble with your car not turning over by hand and looking for causes and solutions, this article is for you. Read on to find out more.

engine won't turn over by hand

What Causes the Engine Not to Turn by Hand?

There are many possible causes of this problem, ranging from electrical to mechanical issues. Here are some of the most common ones:

1. Starter Motor or Solenoid Issues

The starter motor spins the crankshaft when you turn the key. The solenoid activates the starter motor. If either of these components is defective, the engine won’t turn over.

2. Defective Wiring

The wiring that connects the battery, the ignition switch, and the starter motor can become loose, corroded, or damaged over time.

This can cause a loss of power or connection between these components. As a result, you won’t be able to turn over the engine by yourself.

3. Faulty Ignition Switch

The ignition switch is a device that sends current to the starter solenoid when you turn the key. If the ignition switch is faulty, it may fail to send current to the solenoid, preventing the starter motor from spinning.

4. Seized Engine

A seized engine means that a significant part of the engine has stopped moving. It causes the engine to fail. This can happen due to a lack of engine oil, a broken crankshaft rod or piston, or an overheated engine.

Watch this video to learn how easily you can check if you have a seized engine-

5. Hydraulic Lock

When I say Hydraulic lock, that indicates your engine has filled with liquid, usually water, and the pistons cannot compress it.

This can happen if the vehicle drives into a deep puddle or flood. A hydraulic lock can damage the engine and prevent it from rotating.

6. Fuel Delivery Issues

The fuel delivery system consists of the fuel pump, filter, injectors, and pressure regulator.

If any of these components is clogged, leaking, or malfunctioning, it can affect the amount and quality of fuel that reaches the engine.

This can cause the engine to run rich or lean, resulting in poor performance and possible flooding.

7. Engine Mechanical Problems

The engine consists of many moving parts that work together to create power and motion. If these parts are worn out, broken, or misaligned, it can interfere with the normal operation of the engine.

Some examples of engine mechanical problems are a broken timing chain or belt, bent valves, damaged pistons or rings, or warped cylinder heads.

Signs of an Engine That Won’t Turn Over

1. The engine doesn’t start when you turn the key, but the electronics work fine.
2. You hear a clicking or clunking sound when you try to start the engine, but it doesn’t crank.
3. You smell a burning odor or see smoke from the engine bay, indicating overheated wire.
4. You notice a physical defect in the engine block, such as a hole or a crack, caused by a loose or broken part.
5. You hear a knocking or tapping sound from the engine before it seizes and shuts off the car.

Apart from that, another sound you may hear is the clicking noise when you decelerate. Don’t worry, and it could be a sign of a dirty air filter, loose air filter box or air intake system issues. Just replace the filter to solve the issue.

Possible Solutions to Engine Won’t Turn Over by Hand

Depending on the cause, you may be able to fix it yourself, or you may need professional help. Here are some possible solutions that you can try:

1. Inspect and Clean Connections

Sometimes, the problem is as simple as a loose or dirty connection between the battery, the ignition switch, and the starter motor.

You can check the wires and terminals for any signs of corrosion, damage, or wear. You can also clean them with a wire brush or a baking soda solution to improve the contact.

In either case, you should also clean the battery terminals and the starter connections with a wire brush or a baking soda solution. It will remove any corrosion or dirt.

But if the battery or starter connections are damaged, you have to replace the terminal ends or the entire cable.

2. Try Cycling the Key

Another easy solution is to turn the key to the “on” position and wait for a few seconds, then turn it back to the “off” position.

Repeat this a few times, and then try to start the engine. This might reset the computer or activate the solenoid. But if the solenoid is damaged, cycling the key will not help.

To fix a damaged solenoid, check the resistance with a multimeter. If it’s near zero or infinity, the coil is faulty. Replace the coil or solenoid assembly.

3. Tapping the Starter Motor

If cycling the key doesn’t work, you can try tapping the starter motor with a hammer or a wrench. Sometimes, it can get stuck or jammed due to dirt or corrosion. Tapping it lightly might loosen it up and make it work again.

But if the motor is damaged, you will need to remove the starter motor from the engine. Replace the starter motor with a new one.

Moreover, if the damage is not too severe, simple wear and corrosion, it is repairable. Fix it by cleaning the contacts, replacing the brushes, or repairing the solenoid.

4. Fixing a Faulty Ignition Switch

If the ignition switch is worn out or broken, it won’t send the signal to the starter motor to activate it.

You can test the ignition switch by using a multimeter to check the voltage at the starter solenoid when you turn the key.

If the voltage is low or zero, the ignition switch is faulty. You can replace the ignition switch with a new one, following the instructions in your car manual

5. Fixing a Seized Engine

A seized engine can’t be turned by hand or by the starter motor. For that, you can try to free a seized engine by filling the cylinders with engine oil and letting it sit for a few days.

Then, try turning the engine over with a breaker bar or a wrench. If it moves, you may be able to salvage your engine. If not, you will have to pull it apart and rebuild it.

However, this is a risky and last-resort method that should only be done by a professional mechanic.

6. Unlocking a Hydro-locked Engine

To unlock a hydro-locked engine, try removing the spark plugs and cranking the engine. This will allow the liquid to escape from the cylinders.

Then, you can dry the spark plugs and reinstall them. You should also check and fix the source of the liquid leak, such as the fuel injector or the head gasket.

7. Solving Fuel Delivery Issues

If your car has a fuel injection system, you need enough fuel pressure and flow to start the engine. If the fuel pump, the fuel filter, or the fuel injectors are clogged or damaged, they won’t deliver enough fuel to the engine.

So, check the fuel pump by listening for a humming noise when you turn the key on. You can also measure the fuel pressure with a gauge.

If the fuel pump is not working, try smacking the fuel tank to dislodge any debris. If the fuel filter is dirty, replace it with a new one.

If the fuel injectors are clogged, clean them with a fuel injector cleaner.

Sometimes, your engine smells like gas or produces black smoke due to being flooded with excess fuel.

To fix this, you can press the gas pedal all the way down and hold it while cranking the engine. This will allow more air into the cylinders and help burn off the excess fuel.

8. Repairing Engine Mechanical Problems

To diagnose and repair these problems, you need to use-

  • A compression tester
  • A leak-down tester
  • A borescope.

These will help you to inspect the condition of the cylinders, valves, and pistons.

You may also need to remove the cylinder head or the oil pan to access the damaged parts. These are complex and costly repairs that require special tools and skills. You should consult a professional mechanic for these problems.

After that, use a multimeter to check if there is enough power and connection between the battery, the ignition switch, and the starter motor.

Also, use it to test other components such as fuses, relays, solenoids, sensors, etc..

Conclusion

There could be several reasons why the engine won’t turn over by hand. By following my guidance, you may be able to fix your engine and restore your car’s functionality. However, if you are not confident or experienced in repairing your car yourself, consult a professional mechanic for assistance.

Resources

  1. https://www.sciencedirect.com/science/article/pii/S0196890414001939
  2. https://www.electronicshub.org/symptoms-of-seized-engine/
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3231176/

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