Mower engine locked up. 4 Symptoms of a Seized Engine and Causes

11th August 2023

Symptoms of a Seized Engine and Causes

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 significant part has stopped moving, causing the engine to fail. We look at the symptoms of a seized engine, what it means, the reasons why it happens, and how to fix it. So, what are the symptoms of a seized engine?

The most common symptom of a seized engine is nothing will happen when you try to start it. The radio and other electronics may work fine, but the starter will just click when you turn the key. Sometimes you can also smell a burnt smell from the engine.

Here is a more detailed list of the most common symptoms of a seized engine:

Seized Engine Symptoms

Engine Doesn’t Start

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 becomes loose and lodges 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 death knock. This sound often accompanies a piston connecting rod hitting the crankshaft.

What Does A Seized Engine Mean?

A seized engine means it’s stuck, and it won’t rotate when you try to start it. The electronics in your car may work, but nothing will happen when you turn the key. A seized engine is often caused by serious engine damage, which is often very costly to repair.

Seized Engine Causes

The most common cause of a seized engine is that it has been running with a lack of engine oil in the oil pan. It can also be caused by water in the cylinders or a broken crankshaft rod or piston. In many cases, it can also be the result of driving with an overheated engine.

These are just some of the possible causes; here is a more detailed list of the most common causes of a seized engine:

Lack of Engine Oil

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 through a large puddle, water can make 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 gets inside, it could happen. Once parts are rusted, the components grind together, creating 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 rods, 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 leads 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 damage 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 discussed, trouble with the pistons causes the engine to seize.

How to Fix a Seized Engine

Fixing a seized engine starts with determining what the problem is. Many times, the symptoms of a bad starter are quite similar, so you want a proper diagnosis first.

By manually rotating the crankshaft, you rule out the starter. However, if it doesn’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 inspect the timing belt or timing chain timing.

Once you determine that 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. If the mechanic sees a rod through the engine block, it spells trouble.

Additionally, if the engine has overheated, it might have warped internal components, thereby degrading its 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.

FAQs

Can you fix an engine that is seized?

Yes. Seized engines can be fixed, but it is not an easy task, and it can require a lot of money. How expensive it will be, depends on what caused the engine to seize up in the first place. If the engine is stuck due to a broken timing chain or belt, you may need to rebuild the entire engine, which can cost over 5,000.

How do you free up a seized engine?

If your engine has seized because it hasn’t been used for a long time, try filling the cylinders with oil for a couple of hours and then try again. However, if the engine is seized due to damage, the engine needs to be repaired and sometimes even replaced.

How much is my car worth with a seized engine?

A car with a seized engine would likely need a new engine, and that could cost more than the car is worth. So, to figure out how much your car will be worth with a seized engine, you need to figure out how much it will cost to repair or replace the engine. You can expect to get significantly less for your car if it has a seized engine.

Can you trade in a car with a seized engine?

Technically speaking, you can trade in a car with a seized engine. However, most dealerships and private sellers will not accept such a vehicle. For this reason, it’s usually best to sell or scrap a car with a seized engine.

How To Unseize an Engine? Everything You Should Know

The importance of regular car maintenance cannot be overemphasized. Your vehicle’s overall performance relies on regular maintenance. As simple as a motor oil change is, it can make a huge difference and prevent unnecessary car engine repair. If you fail to change your engine oil as recommended by the manufacturer, it will cost several problems in the long run. It may cause engine seizure, requiring overhauling or replacing the engine. If you do not imbibe a regular maintenance culture, you’ll want to start your engine one day and discover that it has seized. If you find yourself in this situation, you may wonder what causes engine seizures. Here, we’ll explain how to unseized an engine, how to check if the engine is seized, and how to prevent engine seizures.

What causes the engine to seize?

Before you can fix any problem, you need to understand the actual cause of the problem. Here are the probable causes of engine seizure you need to know and navigate to when tracking the root cause of the problem.

Low engine oil

Undoubtedly, the low engine oil will cause engine overheating and increased friction in the engine. The motor oil is a lubricant that prevents excessive wear on the internal reciprocating engine parts. It also serves as a layer that separates the cylinder walls and the pistons, hence preventing overheating and friction. Driving with low engine oil will cause excess wear and increased friction, leading to a catastrophic engine breakdown or seizure.

Water in engine

Coolant and oil move in various engine compartments to lubricate and cool the system, but they have different passages. If water enters the wrong passage for any reason, it can seize the engine instantly or in no time. Water can enter the engine in two ways; through flood or a blown head gasket. If you drive your car in a flood or water puddles, the water may enter the engine through the air intake. If this happens, the engine will seize immediately, depending on the amount of water. On the other hand, if the water enters through a blown head gasket, you will notice coolant in oil when you open the valve cover or observe oil in coolant when you open the radiator cap. Either way, this can cause the oil to lose its lubricating properties, causing increased friction and eventually leading to engine breakdown.

Engine sludge

Engine sludge can build up if you do not change your oil regularly. Also, rust can accumulate over time if you park your baby ride for long. Any of these can seize the engine. In addition, rust can come from the gas tank, and that is why you need to check and clean the tank regularly, especially when working on the fuel pump. Another area you should always inspect is the fuel filter. A clogged or dirty fuel filter can transport rust and dirt to the car engine. Although, a dirty fuel filter has obvious signs like rough idling, engine misfiring, hesitation, or stuttering that will force you to trace and replace the dirty fuel filter.

Improper oil circulation

Motor oil is the lifeblood of an engine. Like the human blood in our bodies, your engine oil needs to circulate properly. Reciprocating engine components need adequate lubrication to run properly. And if they have improper oil circulation, it may cause the engine to seize up. A common sign of improper oil circulation is the illumination of the oil light on the dashboard. Improper oil circulation happens when you have a weak or failing oil pump. If this is the case, and you’re asking how to unseized a small engine, all you need is an oil pump replacement.

Damaged or broken engine parts

Internal engine parts like pistons, connecting rods, and other parts can break or become faulty. If this happens, the car will not crank fully and will not start. While this is not common, it can happen in some cases.

Vapor lock

Another probable cause of engine seizure is vapor lock. This occurs when your diesel engine becomes too hot, causing the diesel fuel to be converted to gasoline. Of course, diesel engines cannot work with gasoline. A common sign that this has happened is when your engine sputters and dies off shortly. This mostly happens to old diesel vehicles that have been in the sun for a long period. Don’t worry; we’ll explain how to unseized diesel engines in the subsequent sections.

How to unseized an engine

Regardless of why your engine is locked up or seized, there are possible ways of unseizing it. In extreme cases, it may require rebuilding or replacing the engine. You may wonder how to unseized an engine from sitting or how to unseized an engine that ran out of oil if your engine is seized up due to long sitting or lack of oil.

Confirm if the engine is seized

First, you need to confirm if the engine is actually locked up in the first place. If you’re working on a small car engine, remove the spark plugs and try to turn the engine with a sizable wrench and socket. If the engine fails to turn by hand, it’s locked up. If you’re working on a big vehicle engine, try turning it with a breaker bar and see if it will turn. This explains how to check if your engine is seized.

Unseizing a locked engine from sitting

Assuming the car engine is locked up from sitting, you need to get one of the best penetrating oil for seized engines. A good penetrating oil will do its magic, especially if your car is seized from sitting in the rain, where water may have mixed with the engine oil and gum the piston rings to the cylinder walls. Get a reliable penetrating oil. If you don’t know any, go for P’Blaster. Shoot a large amount of the oil into all the cylinders through the spark plug holes. Ensure you put on your protective gear, especially eye goggles, to prevent the oil from shooting back and hitting you in the eye. Let’s be honest; you need to invest your time here because it requires patience. Apply the penetrating oil every day or once in two days for two weeks. Carefully tap the pistons with a long screwdriver and a tapping hammer whenever you shoot in the penetrating oil. This helps to loosen the rust holding the pistons against the cylinder walls. Try to turn the engine pulley each time you apply the penetrating oil. If the engine is still seized after two weeks, repeat the cycle for another week or two. You should be able to turn the engine by this time. However, if it’s still locked, you have a serious case that needs a mechanic’s attention.

Unseizing a locked engine caused by water in the engine

Roll the vehicle to a safe place or tow it to a garage.
Get the necessary tools and remove the intake manifold, exhaust manifold, and spark plugs.
Turn the engine pulley by hand and see if it will turn. If nothing is damaged, the engine will turn once you exert force on it.

How To Fix A Seized Lawn Mower With Marvel Mystery Oil

The engine will vomit water from both the intake and exhaust sides of the cylinder head. Keep turning the engine until it starts turning freely and there’s no water coming out from the exhaust and the intakes. After that, reinstall everything you removed earlier following the reverse process.

The engine should start at this point. However, If you do not remove the water immediately and leave it for a couple of weeks, you will likely find it difficult to turn the engine. Here’s why I said so, the water may have caused rust on the reciprocating engine parts. In any case, all hope is not lost.

You can use transmission fluid to unseized the engine by pouring the fluid into the plug hole. After pouring the fluid in all the plug holes, allow it to sit till the next day. If you’re lucky, the engine will turn the next day.

I know you’ll wonder, what if the water enters the engine through a blown head gasket? What if it is caused by a broken or bent part? What if the engine is seized due to improper oil circulation? All these problems require a single remedy – engine overhauling.

Overhauling the engine

You need to overhaul your engine if water enters it through a blown head gasket or the engine is seized due to a broken part or improper oil circulation. Unfortunately, this requires disassembling the entire engine components to determine and replace broken, bent, or burnt ones.

Engine overhauls are best left for experienced gearheads. So, you have to contact your mechanic. Unfortunately, this is one of the most expensive car repairs. It will leave hundreds if not thousands of dollar repair bills on the table.

How to prevent engine from seized

No doubt, prevention is better than cure. Avoid engine seizure by following the manufacturer’s scheduled maintenance. Pay attention to the dashboard lights and your engine sounds. If you notice and replace a failing oil pump on time, it will not cause additional problems.

Similarly, if you always pay attention to your engine sound and detect and fix unusual sounds at the early stage, it won’t cause catastrophic damage. Contact your mechanic if you hear a strange noise or see an unusual light on the dashboard. They should know what to do and prevent the issue from escalating.

Q: What is the best fluid for Unseize an engine?

There are several penetrating fluids in the market you can use to unseized an engine. But you have to be Smart when selecting the best penetrating fluid to unseized a locked engine. If you buy the wrong fluid, it may not work or cause more damage to your engine.

The best penetrating fluids you can get are penetration catalyst blaster 16-PB, Liquid wrench L16 penetrating oil, and Kano Aerokroil penetrating oil. But, of course, there are other good ones out there.

You can select one from the ones listed above if you don’t know the one to buy. However, if you don’t have the extra bucks for a penetrating oil, get a 50/50 mixture of transmission fluid and acetone.

Q: Can you fix a seized engine because of no oil?

No matter the cause of an engine seizure, there are probable solutions to rectify the problem. However, if your engine seizes because of no oil, there are limited and expensive solutions to resolve the damages. In this case, the engine may have incurred catastrophic damages and requires rebuilding, salvaging the parts you can, or replacing the entire engine.

Q: What happens if your engine locks up?

Assuming your engine seizes while driving, it’ll make a loud sound, and the vehicle will stop on that spot. It will not start until you track and fix the root cause of the problem. However, this will not prevent the vehicle from rolling, assuming you’re on a steep hill or pushing it.

Secondly, the crankshaft will not turn when you try to turn it by hand. However, kindly note that your engine can partially or completely seize. In case of a partial lock, the engine will turn to a certain point and stop.

It will also return until it gets to that same point. A partially seized engine is mainly caused by bent or broken internal engine parts. A Completely seized engine will not turn at all.

Q: Will a seized engine still crank?

No, a seized engine will not crank. Of course, the most common sign of a seized engine is the inability of the engine to crank. If the engine is partially seized, it’ll slightly turn to a certain point whether you’re turning it by hand or with the ignition key. But it won’t crank normally or start.

Q: How much is it to fix a seized engine?

Since several issues can cause an engine to seize, it is practically impossible to give an accurate repair cost without a thorough diagnosis. However, if your engine is seized due to long sitting or water entered through the intake manifold, you can fix it with around 300 to 1,000.

But if it happened due to lack of oil or improper oil circulation, you likely have bent or broken internal engine components. This will take you around 1,500 to 5,000 to diagnose and resolve the problem.

Final words

Engines can seize for several reasons. And there are several ways to unseize it, depending on the root cause. This article has outlined the possible causes and several ways how to unseized an engine.

If the engine locks when driving in flood or due to long sitting, you could try to fix it yourself. But if it happens due to no oil or improper oil circulation, you need to contact a certified mechanic to diagnose and fix the problem.

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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Riding Mower Won’t Start Just Clicks – Mechanics advice with pics

This is a problem that usually arises in the spring, and for most, the fix is really simple. You’ve come to the right place, and you’ll be cutting grass shortly.

So what’s the problem with a riding mower that won’t start just clicks. The most common reason for a clicking sound on a riding mower when you turn the key is a flat battery. Other possible reasons include:

Yes, it’s a long list, but you won’t have to check all of them; I’ll bet your problem is one of the first three; I have listed the likely causes in order of commonality.

If your mower won’t crank and makes no click sound – Check out “Lawn Tractor Won’t Start.”

Bad Battery Connections

Bad battery connections are very common, and by bad, I mean the power is not passing from the battery to the cables because the battery connections are loose, dirty, or damaged.

Loose Connections

Battery cables become loose because lawn tractors vibrate a lot; this is why it’s a good idea to service your mower at the start of every season, no matter how well she runs.

Dirty Connections

Dirty connections are usually caused by the weeping of battery acid at the battery poles. The acid then crystallizes, causing high resistance; it looks like a white chalky build-up on the connectors.

Cleaning Connections

To clean the connections, add a couple of spoons of baking soda and a small amount of water, and pour this onto the acid build-up on the connections and battery poles.

The soda neutralizes and removes the acid; you’ll need gloves and protective eyewear. After removing the acid, go ahead and remove the connectors and give them a good cleaning with a wire brush or sandpaper.

If you have some petroleum jelly, a small coat will prevent a future build-up.

Connector – Mower blades and engines cause a lot of vibration; bolts come loose from time to time.

Check that both connections, positive (RED ) and negative (BLACK – ), are clean and tight.

Cables – Check the cables for damage, and corrosion; mice find them irresistible.

Flat / Faulty Battery

A flat battery is a real pain in the ass. I know what it’s like; you just want to cut the grass, right? The fastest way to solve this problem is to jump-start the mower.

Leaking Battery – Check your battery for leaks before attempting to jump-start. If it leaks and it’s a sealed battery, replace it.

However, it’s usually only wet batteries that leak, so best to check your electrolyte level and top up if necessary. As you know, the acid will burn the skin and eyes, so, you know, gloves, etc.

If the acid build-up is excessive, your battery may be on its last legs, so don’t be surprised if it fails or does so soon.

But if the leaking is excessive, don’t jump-start; replace it. Batteries are easy to fit; just be sure the battery is the correct size, and the poles are in the proper places.

Jump Starting

You’ll need jump leads and any 12-volt vehicle. Most cars, trucks, and even Hybrids have a regular 12-volt battery fitted somewhere. Sometimes finding it is the hardest part. If you’re unsure of the voltage, when you find the battery, a sticker on the casing will indicate 12v.

Of course, your battery might be faulty, jump-starting will probably get you rolling, but the problem will still be there. You can test using a voltmeter test tool, which I’ve listed here on the “Small engine repair tools” page.

To jump-start – begin by connecting the positive red of the mower to the red of the car.Now connect the negative black (-) on the car to a ground (GRD) source on the mower. (Any bare metal will work)

Connect – If you are not familiar with jump-starting, you’ll find a complete guide here, “Jump starting riding mower.” Add the cables in sequence 1, 2, 3, and 4, start the mower, and while idling, remove jumper cables in reverse order 4, 3, 2, and 1.

Battery Testing

You can check the battery and alternator using a voltmeter. Batteries don’t like sitting idle; they were designed to be charged and discharged continuously. A battery that gets fully discharged will sometimes not come back to life.

Use a voltmeter to check the battery voltage, and connect red to positive and black to negative. I have listed a voltmeter on the “Small engine repair tools page.”

Test – Check battery voltage using a voltmeter – attach a voltmeter to the battery and set it to 20 volts.

If you have a reading above 12.5 volts – go ahead and attempt to start the mower; watch the voltage; a reading below 8 volts is a bad battery and needs to be replaced.

Buying a Battery

When buying batteries – wet batteries will not ship with acid. The acid must be purchased, and the battery must be filled and charged; it’s a lot of work.

I would buy a gel or maintenance-free sealed battery; these can be shipped, fully charged, and ready to roll. Check out quality common ride-on mower batteries on the Amazon link below.

Battery Charging

You’ll need a battery charger to keep your battery in top condition over winter. I recommend a trickle/Smart charger; they’re simple to use; pop on the color-coded crocodile clips, plug it in, and that’s it. Forget it till next spring, then turn the key and mow.

I’ve listed a good-quality Smart charger on the “Small engine repair tools” page that won’t break the bank.

Batteries work best and last longer when their state of charge is maintained; off-season charging is always advised. Check out “Mower winter storage video.”

Charge – Always disconnect the battery before charging. Simply connect red to red, black to black, and plug in the charger. The length of time on charge will depend on how low the battery is and the amp rating of the charger. Usually, 2-3 hours cooking time.

Faulty Solenoid

The solenoid is a large relay of sorts. When you turn the key to start your mower, a 12-volt supply from the ignition switch to the solenoid activates it. The solenoid’s job is to connect the battery to the starter motor and crank over the engine for as long as you hold the key.

The click sound is the solenoid trying to work by pulling in the armature; they fail regularly, and I replace lots of them.

However, the click sound can also be made for a few other less common reasons, and without fully diagnosing, you may find replacing the solenoid doesn’t solve the problem.

Hey, if you feel lucky and don’t want to do the diagnosing part, I understand. So, if your battery is full and the cables are tight, go ahead and replace the starter solenoid. They’re cheap and easy to fit.

Check out, “Mower solenoid repair tools” it lists useful tools and parts that will help you nail the repair.

Solenoid – Solenoids are a universal fit; they give lots of trouble.

On the upside, they’re easy to fit and cheap to buy.

Where’s the Solenoid?

Often just finding the starter solenoid can be challenging; I sometimes think that they hide them for fun. If you don’t find it under the hood, try under the rear wheel, behind the gas tank, or under the seat.

The easiest way – follow the red battery cable from the battery. On some engines, the starter and solenoid will be one unit (Kawasaki and Honda engines).

Small Engine Locked Up? Easy Fix: How to Unlock Seized Motor

Where? – Husqvarna, craftsman-like to, hide theirs under the rear wheel fender or the dash beside the steering column.

However, most solenoids will be easy to locate. Fitting is easy, but do disconnect the mower battery first.

Solenoid Test

Remove – The first step in testing the solenoid – remove the spark plug.

If, when removing the spark plug, gas pours from the spark plug hole – move on and check “Carburetor troubleshooting.”

Test – Turn the key; if the clicking sound persists – Go ahead and replace the solenoid.

If, on the other hand, the engine cranks over, move on and check for excessive valve lash.

Tight – Check the solenoid terminals; all wiring should be secure and free from corrosion.

Binding Starter Motor

The gear head of the starter motor can bind against the flywheel; this locks the engine and starter motor together. So when you hit the key, all you hear is the click sound.

Testing

Testing for this condition involves turning the engine by hand anti-clockwise. Some engines will have a cover over the flywheel; if so, try turning the crankshaft with a ratchet and socket from the underside of the engine.

If turning the motor anti-clockwise frees it up – you have found your problem, the starter motor is binding. Usually, a spray of wd40 on the starter gearhead will fix it. If you are lucky, you can get the straw of the WD40 directed at the gearhead without removing any covers.

Starters can bind for other reasons – worn bearings, worn gear head, misaligned or loose starter motor.

Binding – Starters can bind against the flywheel. To fix it – spray the starter gear with wd40 and retest. If it continues to bind, replace the gear head or complete the starter motor.

Turning the engine anti-clockwise by hand will unlock it.

Excessive Valve Lash

Engines have valves that open and close in sequence. The inlet valve allows the fuel/air mixture in. It then closes and seals the combustion chamber. After the power stroke, the exhaust valve opens and allows spent gases out.

What’s Excessive Lash?

The valve lash describes a precise gap between the valve tip and the rocker arm. As the engine wears, this gap gets bigger and must be adjusted. The inlet and exhaust valve lash will usually be different specs.

Correct Lash

When the valve lash is set correctly – you crank over the engine, the valves open, and release cylinder pressure. This allows the engine to crank over at sufficient speed to create a spark strong enough to start up the engine.

When the valve lash is out of spec, the valve is late opening which means pressure in the cylinder is too great for the starter to overcome; that’s when you hear the click sound.

Incorrect Lash

Check out “Valve lash adjusting” it’s for a walk-behind mower, but the process is identical. Adjusting lash isn’t difficult but will require an inexpensive tool called a feeler gauge. You’ll find a link to a good feeler gauge set on the “Small engine repair tools” page.

Test – If you can, place your hands on the flywheel screen – try turning the engine clockwise.

If you’re unable, you likely have excessive valve lash. Lash should be checked every season.

Lash – Adjusting valve lash requires an inexpensive tool called a feeler gauge.

Hydro-locking

A carburetor fuel supply usually consists of a fuel bowl, float, and needle. The float is, as its name suggests, a float. Attached to it, is a needle with a rubber tip.

The function of the float is to lift the needle as the fuel level rises in the fuel bowl. When the fuel bowl is full, the needle will be pushed against the fuel feed port, sealing it.

Hydro-locking – Worn carburetor float needle seals have a habit of leaking gas into the cylinder, and when the cylinder is full of gas, the piston can’t move; this is known as hydro-locking. Because the piston can’t move, the engine will often make a clicking sound as you try to start the engine.

Removing the spark plug and turning over the engine will release the gas, but the carburetor float valve and the engine oil will need to be replaced.

Other signs that your carburetor needle seal leaks are: overfull oil level; white smoke from the muffler; oil leaking from the muffler; gas dripping from the carburetor; a strong smell of gas in the garage.

Fuel Valve Solenoid

Newer model carburetors have a fuel solenoid fitted to the bottom of the fuel bowl; its function is to stop the fuel supply when you shut the engine off. So if you have this newer type of carburetor fitted, you will not likely have a hydro-locking condition.

Leaking Carburetor Valve Seal

Failure commonly occurs in the older type carburetor when the rubber needle seal wears. This results in fuel filling the carburetor and eventually entering the cylinder and crankcase.

Gas in the Oil

If you have gas in the oil, don’t run the engine; the diluted oil offers little protection to internal components. First, fix the issue by replacing the carburetor and then changing the oil.

Check out “Carburetor types” page; it lists popular mower carburetors. Check out “Carburetor troubleshooting” also for more details on the issue.

Check Oil – Too much oil is a sign that your carburetor needle seal is leaking unless, of course, you overfilled the oil yourself.

Needle – The needle wears over time; they turn pink when worn. The fix – replace the seal or the complete carburetor. Using your manual fuel valve will prevent future problems.

Faulty Ignition Switch

A faulty ignition switch can cause all kinds of problems; the click sound can be caused by a bad connection in or at the back of the switch.

Try the Wiggle Test

When turning the key, wiggle the wiring at the back of the ignition switch and see if it makes a difference. It will very often show you where the fault is. Wiring pinouts are specific to each manufacturer.

Wiggle – Try wiggling the wires at the back of the ignition switch while attempting to start the engine; you may need a helper.

Often wires come loose but do check them for corrosion.

Faulty Control Module

Control Modules are not fitted to all mowers. The function of the control module is to receive a start request from the ignition switch and to output a 12-volt supply to the starter solenoid, but only if all safety sensors are in the correct position.

Control Module Test

Control modules do fail and also suffer from loose connectors. Try the wiggle test on the connectors and check for obvious signs of water/corrosion damage. The control module will often live behind the dashboard in a plastic box about the size of a mobile phone.

Wiggle – Like the ignition switch; wires come loose, have a helper attempt to start the engine while you wiggle the wiring connectors.

Check also for damage, water, or scorch marks on the panel itself.

Faulty Starter Motor

A faulty starter can fail electrically, mechanically, or both. Electrically – the copper winding can break; brushes can break or wear out. Mechanically – the top and bottom bearings and the gear head can wear. These issues can cause the starter to bind, so all you hear is the click sound.

Testing the Starter

Checking the starter motor is easy; connect a 12-volt supply direct from the mower battery to the supply wire at the starter. An even easier way is to cross the starter solenoid as per the guide below.

If you find your starter has failed, removing and fitting a new one is simple. The starter motor for Briggs and Stratton offers a good quality starter. Be mindful that BS has two types of starter – plastic gear head or metal; check before ordering.

Starter – Some starters will have a solenoid and starter motor combined in one unit.

To test, use a jumper lead to bring power from the positive of the battery to the positive post of the starter. If the engine doesn’t crank – Replace the starter.

Common – Most mowers will have the starter and solenoid separate.

Solenoids are fitted to the body, usually under the hood.

Test – Cross a metal screwdriver from one connection to the other, as per the picture.

There will be arcing (sparking) as the screwdriver contacts the poles.

RISK OF FIRE – Keep clear of gasCAUTION THE ENGINE MAY TURN OVER – Place the mower in the park with the parking brake applied and the blade off.

If the engine doesn’t crank over – your starter is faulty; replace it.

Internal Engine Damage

If you’re still reading, I fear the worst has happened. It’s unusual for mower engines to fail completely. They’re generally well-built robust units. I have seen failures like the con rod breaking out through the engine casing; the main bearing seizing; the con rod bending; cylinder head failures.

Some of these faults can be repaired, but most are uneconomic to repair.

New Engine

On the upside, if you have a total failure, a complete engine fully built with a guarantee is available, and fitting involves four bolts, two electrical connectors, a fuel line, a throttle cable, and a crank pulley.

BS and Kohler’s engines are of great quality and ready to go. The completed job will take less than two hours. Be mindful that all engines are shipped without oil.

Failure – Total failure doesn’t happen often.A hard life, and low/poor quality oil, without doubt, increase the chances.

Seized Or Locked Engine? Here’s How You Fix It

Is your car’s engine suddenly seized or locked? A completely seized engine is very rare, so it can definitely be fixed. Here’s how you fix a seized engine.

This author has been vetted and has the necessary know-how or education to be able to write about this topic. Learn more on our about page.

Motion. This is what allows a car motor to produce power.

Without it, everything would cease to function.

If your engine decides to lock up on you, then you’ve got a real problem on your hands.

So what causes an engine to seize?

The most common cause of a seized engine is a lack of oil. Oil lubricates the pistons so they can move within the cylinders. Without it, metal would scrape against metal and create a lot of heat. Too much, and things can fuse together, causing the engine to seize.

But that’s not the only reason an engine will seize, there are several more to be aware of, each with its own solution.

Thankfully, in this guide, I will cover everything you need to know about a seized or locked engine, including how to fix it.

Let’s cover the basics first!

What Causes An Engine To Lock Up, And What Are The Symptoms?

Before you can proceed with an actual fix, you have to know what caused your engine to lock up in the first place. There are three primary reasons an engine might decide to seize, a lack of oil, a lack of circulation, or a lack of use.

However, those are just the ones that have to do with oil. There are also hydrolock and vapor locks to consider.

Don’t worry. We’ll cover each of these now.

Lack Of Oil

As we mentioned above, if your engine doesn’t have enough oil, it will eventually seize. This is because oil creates a thin layer between the cylinder walls and the pistons, allowing them to move without getting too hot.

Take away that layer, and you’ll have metal scraping against metal, which creates a lot of friction and, therefore, heat. Imagine rubbing your hands together quickly, then imagine doing the same thing while wet.

This will eventually result in damage to the crank journals, the rod ends, or the main caps, which are all items your engine can’t run without.

It is also possible that the rods fuse to the crank, which can cause the pistons to “fling” out the side of the block. In this case, you’re looking at an extremely costly repair bill.

Thankfully, if you follow a factory service schedule and regularly change your oil, you should be able to avoid this cause altogether.

Symptoms of your engine being low on oil include:

Burning oil smell
Engine overheating
Oil pressure indicator
Knocking/clunking sounds
Drop in performance

Lack Of Circulation

If running out of oil can cause an engine to seize, then it should come as no surprise that the same thing can occur if it can’t circulate in the first place.

We’re talking about the oil pump, which is in charge of “pumping” the oil from the gas tank to the various components that need it. If it ends up failing, then your engine may seize.

Signs your oil pump is failing include:

Catching a faulty oil pump as early as possible is crucial. Doing so is the difference between a 300 repair bill and a 3,000 one (or more).

Similar to the previous cause, routinely replacing your oil is essential for your oil pump to remain running strong.

Do not forget to change your oil filter as well, which removes harmful particles like dirt, dust, and metal before they reach the engine.

Lack Of Use

Have you ever sat in one position for so long that when you go to move again, you feel stiff, and it hurts? This is also possible with a car engine if it’s been sitting for too long without use, which leaves it exposed to corrosion (AKA rust).

When rust takes hold inside the cylinders, it can cause the piston rings to become stuck in place.

How do you know if your engine has seized from lack of use? If the interior lights are working and you can turn the key in the ignition, but it won’t crank, then your engine may have locked up.

Another possibility is an electrical short in the starter, which is caused when it can’t turn the engine over.

If a small smoke Cloud appears from under the front of your car while turning the key, you may have a seized engine (as well as a faulty starter).

The good news is that you can avoid this by starting the engine every month or so. To be extra safe, you should check for leaks as well. This will help avoid the first cause of a seized engine, a lack of oil.

Hydrolock

What does it mean when an engine is hydrolocked?

Engine pistons are designed to compress a mixture of air and fuel – not water. Because of this, if enough water enters the cylinder, it may hydrolock, meaning they all stop moving at once. Much of the resulting damage depends on how fast you were going when it happened.

The most important thing about a hydrolocked engine is taking care of it quickly before it begins to rust or cause damage inside the cylinders.

Vapor Lock

While it’s not as common as the other reasons your engine might have locked up, vapor lock does happen. Vapor lock results from a fuel system issue where the liquid inside becomes too hot, causing it to become a gas, which your engine isn’t made for.

If you notice your engine sputters and then loses power, it may be due to vapor lock. However, it’s mostly found on older cars, especially if they’ve been left out in the sun too long.

How Do You Fix A Seized Or Locked Engine?

Ready for the bad news? If your car engine is seized from a lack of oil or circulation, especially if you were driving at the time, then your options are limited. In this case, your engine is likely ruined and will either need to be rebuilt or replaced, salvaging the parts you can.

If a rebuild is possible, you’re looking at a cost between 2,500-4,500. If the only option is to replace a seized engine, then the tally jumps to between 4,000-8,000 (or even more).

Both repairs include tearing down the engine, assessing each part, replacing the bad ones, and reassembling it all again.

Some more bad news? Insurance rarely covers the costs of a seized engine, so if you’re outside your factory warranty, things become a little bleak.

Thankfully, if you’re following a factory maintenance schedule, you should be able to catch any issues before they cause your engine to seize.

For a vapor locked engine, the fuel needs to cool to the point that it condenses back to a liquid. Your best bet is to let it sit, though, you can also splash some cold water on the fuel pump and fuel lines if you’re in a hurry.

As for how to fix a hydrolocked engine, check out our previous article here for a detailed guide.

Don’t Despair – Prevent The Repair

It’s that simple, just avoid it all by following your factory maintenance schedule and regularly changing your oil. On top of that, pay attention to any changes in how your engine sounds and performs.

If something doesn’t feel right, take your car to a professional and have it diagnosed.

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Josh Barrett is a writer hailing from the great state of Alaska. While describing himself in the third person is not his forte, writing about any and all things automotive – is. After 13 years hustling in the exciting world of car sales, he took off to travel the world with his dog Teemo.

Sources:

https://mechanicbase.com/engine/seized-engine-symptoms/
https://rxmechanic.com/how-to-unseize-an-engine/
https://www.lawnmowerfixed.com/riding-mower-wont-start-just-clicks/
https://autochimps.com/seized-engine/

Lawn Mowers engine, locked, mower, symptoms