Nothing is more stressful than a stubborn lawnmower. It is the start of the mowing season and you want to remove the unnecessary grass from your lush green turf but your lawn mower just does not respond. The engine does not turn on and if it does, it produces some annoying grinding noises.

If that is the case with your mower, its engine seized up and that is the reason your mower cannot start. You might be wondering how you can tell if your riding lawn mower is seized, don’t worry, this article has the information you need. 

First things first, the engine is the most vital part of your lawn mower. It provides the power that the machine needs not only to start up but to propel and get the work done.

As such, if your lawn mower engine is seized, then the machine won’t work. Besides, the lawn mower engine can also seize while the mower is running. 

A lawn mower is one of the most essential lawn care and maintenance tools and as such, experiencing some technical issues with it may make you feel disgusting. Don’t worry if your mower engine is seized. In this article, we’ll cover all you need to know about the seizing of your engine.

How to tell if riding lawnmower engine is seized, step by step

  • Check for Unusual Sound/Noise
  • Excite The Mower’s Engine
  • Inspect The Blades
  • Inspect The Piston Cylinders
  • Check The Oil Level
  • Check The Fuel Condition

How to Tell If Riding Lawnmower Engine is Seized? – Easy Fix

So, how do you know that your lawn mower engine is seized? Surprising, you won’t be able to use your mower. For instance, its blades won’t move. In short, seizing means that the engine is not performing and thus it won’t start or cause propulsion therefore, no lawnmower advantage.

How to Tell If Riding Lawnmower Engine is Seized?

Luckily, there are various ways in which you can know that your lawnmower engine is seized, they include:

1. Check for Unusual Sound/Noise

Usually, a lawn mower is usually loud when working on the grass. In most cases, if your lawn mower engine already is or is about to be seized you won’t be able to start it. However, if you somehow manage to start it, it will only run for a short period.

Normally, it will run for only a few minutes, and then it will die off again. Meanwhile, when it is running, you are most likely to hear loud grinding noises as if its internal components are smashing. If you hear such sounds, it is a sign that your lawn mower’s engine is not in the right order.

2. Excite The Mower’s Engine

Mainly, there are two things you will notice when the engine of your riding lawn mower is seized. To start with the most common, you will not be able to start your engine.

In this case, the motor will not start, the brakes will be stuck up and even if you try to pull the cord, it will not bulge since it’s tightened. In the second case, if you attempt to start your lawn mower, it may start up but produce very loud irritating noises before switching off again. 

3. Inspect The Blades

As you’ve already seen, another sign of a seized engine on your riding lawn mower is a stuck blade. Remember that for an efficient lawn mower, the blades can easily rotate. However, stuck blades mean that the blades will be hard to move.

Whether you try moving them with your own hands or with another tool, they simply won’t bulge. This situation will oppose the starting of the engine. 

4. Inspect The Piston Cylinders

Usually, when a riding lawn mower engine is seized, the machine may have some jamming or damaged parts. In most cases, the pistons get stuck in the cylinders. Some of the things that can lead to the seizure of your mower’s engine include oil shortage, water, or excessive moisture.

To check the piston cylinders, start by removing the spark plug. This is a safety precaution to avoid accidental startups of your machine. Next, you can remove the seal and take off the engine’s cover and inspect the piston cylinders.

Nevertheless, do not interfere with your machine if you are not sure how to fix the problem – it is better to leave it to the professionals.

5. Check The Oil Level

Oil deficit in your lawn mower is another major issue behind a seized engine. The oil in your machine greases the moving pistons thus ensuring that the engine operates efficiently. A reduced level of oil leads to a shortage in lubrication.

And this can potentially block the pistons. Therefore, you should regularly inspect the oil level in your riding lawn mower. 

6. Check The Fuel Condition

If the engine is enclosed, the oil in the chamber can clog. In the same way, an incorrect air-fuel ratio will burn in the combustion chambers. Besides, the incorrect flaming can also cause debris to stick to the chamber leading to the downfall of the piston working.

Listed above are the indications that your lawn mower engine is seized. If you notice any of these, read on to understand how you can unseized the engine.

What Are The Signs Of A Seized Engine?

So, you are just about to start mowing your lovely lawn, you turn on the ignition key but you only hear a clicking sound or detect a burnt smell from the engine.

In the same manner, the lawn mower may start but produce some loud annoying sounds before turning off again after a short period. These are some of the signs of a seized engine. In this section, we’ve detailed a list of the most common signs of seizure in your engine:

  • The Engine Fails To Start

The most prominent sign that your lawn mower engine is seized is a complete failure of the engine. In this case, no matter how much effort you put into getting your mower up and running, the engine will not start. Nevertheless, you might still be able to use other battery-operated devices like the lights. On turning the ignition key, however, nothing happens. 

  • Burnt Wires/Fumes

Although one of the sure signs of a seized engine in a lawnmower is burnt wires, the seizure itself does not create burnt wires – it is what results after the engine fails. As you attempt to start your lawn mower, additional damages occur.

Since the starter is not able to crank the engine, the wires start to overheat after several attempts. You will notice smoke and a burning smell from the mower’s engine. In worse situations, this overheating may even cause a fire. 

  • Blaring Engine Noises

Shortly before your lawn mower engine seizes, you will hear booming or clucking sounds. At times, these sounds appear as light tapping. Whichever the case, your engine is about to seize. The actual seizure is accompanied by a dead knock.

  • Physical Defect

The engine of your lawn mower may seize due to the loosening of an internal part. For instance, if a piston connecting rod loosens, it may pierce through the engine block. A clear inspection may reveal this problem. 

How Do You Unseize A Riding Lawn Mower Engine?

If your lawn mower engine is seized and you want to save a few dollars, by fixing it yourself without the help of a mechanic, you are in luck, All you need is a freeing fluid or cleaner and your engine will be back to work in a jiffy.

In most cases, a lawn mower engine can seize after winterizing your machine or due to the lack of enough motor oil.

Step 1: Remove The Spark plug

This is a safety precaution whenever you are trying to fix any defect associated with your lawn mower. This step prevents your machine from accidentally starting for instance when you are pulling and cleaning the cord. 

Step 2: Clean the Combustion Chamber

The next step is to spray an ideal aerosol through the spark plug hole to the piston and combustion chambers. For this purpose, you can use aerosol sprays like Blaster PB or WD-40 from the nearest store. Remember to use protective gloves.

The spray acts as a lubricant to remove the clog buildup. After leaving the fluid in for a few hours, you can drain it through the spark plug hole.

Step 3: Gently Tap on the Mower’s Piston Cylinders

Sometimes, you’ll need to do something more than use an aerosol spray or cleaner. You’ll need to open the head of your engine, and hit the piston head using a wooden hammer. You can also lubricate the piston rings and replace damaged seals. 

Step 4: Check the Motor Oil

From the basics, we’ve already seen that oil shortage can lead to engine seizures. As such, you need to regularly check the oil level not just in the chamber but in the gas tank. Ensure that you put enough oil into the tank, preferably the oil type recommended by the manufacturer. 

Step 5: Reassemble Your Lawn Mower’s Components

Finally, after all the technical work is done, you can conceal all the lawn mower parts as they were taken out. 

What Happens When Lawn Mower Engine Seized?

When the lawn mower engine is seized, then your machine will not start. If you are lucky enough to start it, the mower will run for a very short time and then shut off again. If your engine seized up, it’s most likely because of an oil deficit in the chambers.

Oil provides sufficient lubrication and without it, there is extreme friction between the piston and the housing making the force generated in the combustion chamber to be lower than the ideal amount needed to start the engine. 

As such, it becomes impossible to pull the starting cord meaning it has been tightened. Besides, when you turn over the lawn mower and try to rotate the blade with your hand, it feels stuck and you cannot move it even with another tool. 

What Does A Seized Engine Sound Like?

Dealing with a seized engine can be very hectic so it is better to avoid it. Luckily, there are distinctive engine sounds that foretell the impending disaster. So, whether your engine is seized or it is about to, you don’t have to worry since you will be aware of what you are dealing with. 

At the initial stage of the seizure, light tapping or knocking sounds are common especially when operating your lawn mower. You will notice that the noises seem to originate from your mower’s engine. After a while, you will hear tremendous knocking sounds barring metallic striking.

This stage involves the piston rod banging into the crankshaft and it is normally known as the “dead knock” These sounds are the early symptoms of a seized engine.

You should diagnose your lawn mower sooner, this helps you save hundreds of dollars. 

How To Un seize An Engine That Ran out of Oil?

To ignite a seized engine that ran out of oil, follow the following simple steps:

  • Disintegrate

You’ll need to remove the crankshaft as well as the cylinder head and check for faults by examining the tubes. For a lawn mower engine that seized due to lack of enough oil, the main solution is to release the stuck piston. If the piston is still stuck, you should consider looking for professional help.

  • Check for The Damage

At this step, examine the rings of the piston to ensure that everything is okay. You can even replace the rings if need be. An engine that is seized due to an oil deficit can potentially distort the pistons. Clean it well and inspect the skin for damage, if any, and consult a professional. 

  • Check the Bottom and Reassemble

If you noticed knocking sounds from the engine, it’s most likely that the pins are worn. When the pistons are in place, use a clean engine and coat both the piston and the cylinders. Besides, you can use a compressor if you are installing new rings. Reassemble all the pieces correctly and turn on the engine, it should be running correctly. 


Identifying whether you have a seized engine on your lawn mower or not is quite simple, all you need to do is use either of the above methods and do the diagnosis. If your lawn mower engine is seized, you can easily unseized it. Alternatively, you can also leave it to a professional. 

Honestly, regular care and maintenance keep your lawn mower’s engine in good shape. Hopefully, this article has shed some light on the idea of dragonizing your lawn mower for seizure and fixing a seized engine.

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Victoria Peterson

I am a passionate gardener who wants to help you create and maintain your dream yard. I know that it can be daunting to take on a project like this, but I am here to help. I have been gardening for years and have learned a lot along the way. I want to share my knowledge with you and help you create the perfect yard for your home.

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