Riding mower engine seized. Lawn Mower Struggles To Turn Over: 6 Immediate Things To Check

Too Much Oil In Lawn Mower? Read Our Easy Fix It Guide!

Outdoor Happens is reader-supported. When you buy through links on our site, we may earn an affiliate commission. Click to learn more.

What happens with too much oil in the lawn mower? Well, too much of a good thing can be bad for you! Right? Well, the same law applies to lawn mowers and engine oil. An overfilled lawn mower oil tank will lead to performance problems, failed starts, or an oily overflow mess. And much worse!

So, what other engine issues arise from putting too much oil in a 4-stroke lawn mower? And are these issues easy to fix?

Too Much Oil In Lawn Mower

Overfilling a lawn mower oil tank will negatively affect engine performance and possibly prevent the mower from starting. Too much oil in a lawn mower can easily clog the air filter, foul spark plugs, and potentially cause a hydro-lock, which could bend the connection rods in a multi-cylinder mower.

The way 4-stroke oil works in a 4-stroke walk-behind single-cylinder mower or a multi-cylinder lawn tractor is surprisingly straightforward:

  • Lawnmower engine oil lubricates the engine and helps to keep it cool.
  • The oil tank on a lawnmower feeds oil into the crankcase, where it is placed under pressure by the down-stroke of the piston during the combustion process.
  • The air pressure forces the oil upwards to lubricate the piston and cylinder, as well as the crankshaft and con rod (piston push rod).
  • The crankcase has a ventilation valve (breather) that releases pressurized vapor, which forms an oily mist.
  • A rubber hose connects the ventilation valve to the mower’s air filter housing and carburetor air intake.
  • The crankcase vapor passes through the air filter to the carburetor, where it mixes with the gasoline that fuels the engine.

What Happens When You Overfill the Oil In Your Lawnmower?

Too much oil in a lawn mower crankcase causes the vapor released via the ventilation valve to become oil-rich, which clogs the air filter, creating an overly rich air-to-fuel ratio that fouls the spark plugs and causes the engine to smoke and run poorly. Extreme over-oiling will stall the engine.

With too much oil in the mower’s oil tank, an excess amount of oil feeds to the crankcase, effectively reducing the volume (air space) of the crankcase, which increases the pressure in the crankcase during the piston down-stroke.

  • The increase in pressure will force the excess oil through the ventilation valve into the air intake. From there, it will clog the air filter.
  • The oil-rich vapor (potentially pure oil in extreme cases of over-filling) will enter the carburetor and blend with the gasoline that powers the engine.
  • The overly rich air-fuel mixture will enter the combustion chamber and foul the spark plugs, causing the engine to sputter and stall.
  • A severely over-filled lawnmower oil tank (and crankcase) will cause a hydro-lock, where the piston cannot move due to excess oil filling the combustion chamber (between the cylinder head and the piston crown).
  • A hydro-lock has a similar effect to a seized engine – the engine stalls and won’t restart.
  • Attempting to crank the engine of a multi-cylinder mower when hydro-locking has occurred could bend the con rods (piston push rods).
  • Hydrolocked single-cylinder lawnmower engines generally don’t suffer con rod bending.

How Do You Know If You’ve Put Too Much Oil In Your Lawn Mower?

You’ll know you’ve put too much oil in your mower when:

  • The oil on the dipstick is above the upper indicator line.
  • Excessive smoke emits from the exhaust.
  • The engine runs roughly and sputters.
  • The engine stalls and won’t restart.
  • The spark plug is oily.
  • The air filter is oily.

Can You Put Too Much Oil In Your Lawn Mower?

Yes! You can put too much oil in a lawn mower if you fail to limit the volume of oil poured into the oil tank to the amount specified by the mower manufacturer. And filling oil into the mower directly from a large oil can without checking the dipstick as you fill the tank can lead to over-filling.

Note: Consult your lawn mower owner’s manual for the correct oil volume and grade.

Oil volume ballpark – Lawn mower oil volumes generally vary between 15oz to 20oz, ranging from single-cylinder walk-behind mowers to larger multi-cylinder ride-on mowers.

What Are the Risks of Overfilling a Small Engine With Oil?

The risks associated with overfilling a small engine with oil include the following.

  • Bent con rods – which may require expensive engine repair!
  • Your lawn mower air filter may spoil.
  • Your lawn mower spark plugs risk soiling.
  • Wasted oil – the ultimate sin for thrifty homesteaders!

What to Do When You’ve Put Too Much Oil In the Lawn Mower? Easy Fix!

The best way to fix an overfilled lawn mower is to drain the engine oil from the oil tank, crankcase, and combustion chamber. Remove the air filter and spark plug and clean them to remove all traces of oil. Crank the engine several times with the spark plug removed to purge residual engine oil.

How to Fix a Failed Mower Engine Due to Oil Overflow?

Do you need to fix a lawn mower that’s stopped running due to oil overfilling? Then follow these steps.

Get the Right Tools, Including the Following:

  • A jug or can of the specified oil for your mower.
  • A spark plug wrench.
  • A screwdriver or wrench. These tools help to remove the air filter.
  • A wrench! Wrenches are perfect for removing the oil drain plug.
  • Pliers to remove the ventilation hose.
  • A solvent. It helps to clean the lawnmower spark plug.
  • Detergent! Warm water with grease-cutting soap works fine. It helps to clean the air filter.
  • A plastic funnel.
  • An oil drain pump – but only if the mower lacks an oil drain plug.
  • An oil drain hose – is critical for ride-on lawn tractors.
  • An oil drain pan.
  • A measuring jug.
  • Paper towel.

Troubleshooting Your Lawn Mower – Step-by-Step

  • Disconnect the spark plug boot and remove the spark plug from the engine.
  • Remove the air filter cover and ventilation hose.
  • Remove the air filter.
  • Clean the spark plug.
  • Clean the air filter and dry it with a paper towel.
  • Lightly oil the air filter to prevent it from drying out and perishing.

Drain All the Oil From the Crankcase and Oil Tank – Step-by-Step

  • Remove the oil drain plug (on the side of the engine or under the deck) and drain the oil into an oil drain pan (large mowers may need an oil drain hose to attach to the oil drain valve).
  • Pump oil out of the oil tank (for mowers without an oil drain plug) into an oil drain pan or disposable bottle.
  • Tip the mower on its side with the oil tank cap removed (for mowers without a drain plug). And drain oil from the oil tank and crankcase into an oil drain pan.
  • Crank the engine several times to vent oil vapor from the spark plug hole and crankcase ventilation hose.
  • Let the mower stand with the spark plug, oil drain plug, and air filter removed for 45 minutes to evaporate oil-vapor residue.
  • Refit the cleaned spark plug, air filter, and ventilation hose.
  • Screw in the oil drain plug.
  • Pour the manual-specified amount of oil into a measuring jug (you can DIY a used canned fruit tin or similar).
  • Fill the oil from the measuring jug into the oiling tank via a funnel.
  • Allow the oil to settle for two minutes.
  • Screw in the dipstick and oil cap.
  • Unscrew the dipstick and check the level. Top up if necessary. But don’t go over the upper marker line on the dipstick.
  • Screw on the oil tank cap.
  • Crank the engine. The mower should start.
  • Allow the mower to idle for a few minutes.
  • Smoke will emit from the exhaust as the engine burns away the remaining oil residue.
  • Stop the mower and check the dipstick. Top up the oil if necessary using the measuring jug.
  • Cut the lawn!

Conclusion – Re-Oiled and Ready to Mow

If you’ve overfilled oil in your lawn mower, don’t beat yourself up – it’s a common mistake! And, the remedy needn’t cost much more than the price of a new can of oil.

Irrespective of what type of mower you own, having the right tools for the job and following our step-by-step oil overfill fix will get your mower back into the field. Pronto!

In the meantime, let us know if you have more questions about what to do if you put too much oil in the lawnmower.

We have tons of experience tinkering with lawn mowers, tractors, engines, and small farmyard equipment.

And we’re always happy to help troubleshoot.

Too Much Oil In the Lawnmower References, Guides, and Works Cited:


Dan is our qualified diesel fitter and automotive mechanic. He’s been fixing machinery for over 30 years and has a real passion for the old stuff. he loves reviving things that others have given up on. He’ll fix anything with a cable tie and fencing wire and has had his hands on everything from log skidders, trucks, agricultural implements, tractors, and huge mining gear to outboard motors. He’s plagued by OCD. but that makes him a helluva mechanic! View all posts

Paul writes for a living, about trucks mostly. He lives away from the city and off the road, nurturing his love for all things outdoors –- like tiny house construction, country cooking, bushcraft, woodwork and power tools, alternative energy, and minimalist living. If there’s a way to Do It Yourself, Paul wants to hear about it, and try it out. Then he’ll write about it, and share his story with blog readers around the world. Paul was raised on a South African homestead where he tended two horses, a Jersey cow, and half a mile of split pole fencing. At age 16, he bought a dirt bike, pirated a punk rock compilation, and commenced a blind-rise adventure that continues to this day where words, Wabi-Sabi, cooking, all-terrain tires, and all things to do with canvas and wood are his fodder. His overarching existential question is – “What more does a man need than a cast iron pot and a pair of loose-fitting trousers?” View all posts

riding, mower, engine, seized, lawn

Lawn Mower Struggles To Turn Over: 6 Immediate Things To Check

Lawn mowers can occasionally struggle to turn over due to potential issues in the fuel system, filters (air fuel), or the spark.

If your riding lawn mower struggles to turn over, inspect the current state of the fuel, spark plug, filters, battery, starter, solenoid, and engine blades to either repair or replace the faulty elements.

Fortunately, it’s relatively easy and convenient to resolve when a lawn mower won’t turn over with simple DIY solutions.

Reasons Why Riding Lawn Mower Struggles to Turn Over

The most common reasons behind turnover failure are:

  • Empty Fuel tank/does not have enough Fuel/Bad Fuel/Problem in the Fuel Flow
  • Defective Spark Plug Lead
  • Dead Battery or Battery Connection Error
  • Clogged/Damaged Air or Fuel Filter
  • Faulty Solenoid or Starter
  • Seized-up Engine Blades

Check Fix Your Lawn Mower That Struggles to Turn Over:

Check these top six things before approaching a professional and consulting about your riding lawn mower struggles to turn over.

Checklist of the required tools and materials:

Tools Materials
Standard Mechanical toolkit New Spark plug leads
Spark plug Gapping tool Solenoid replacement kit
Wire brush New Starter kit
Spark plug cleaner New Battery Connectors
Spark plug wire tester/Multimeter
Protective Gloves

Bad Fuel or Fuel Flow

The first thing that one should check is the fuel condition of your mower.

If the fuel tank is empty or does not have enough gas, your mower will likely fail or struggle to start over.

You will witness a similar issue if you have not changed the fuel for a while, and it has been sitting for over 30 days.

A Similar issue can arise if fuel could not reach the engine or motor due to any interruption in the fuel flow system.

An unexpected increase in fuel consumption due to leaks in the tank can also lead you to encounter such an issue.

How to Fix

Diagnose whether you have old or bad gas in the fuel tank and replace it with an adequate amount of fresh gasoline.

Look for a leak presence in your fuel tank and fix it accordingly.

If fuel fails to reach your mower engine, tap on the carburetor to clear the flow line.

Inspect whether the carburetor is clogged or severely damaged, and clean or repair the carburetor as needed.

Defective Spark Plug Lead

A broken/damaged spark plug can drive your mower to struggle. Even loose, disconnected, or worn-out spark plug leads can also cause your mower to stumble.

How to Fix

Disconnect the spark plug lead and check the condition.

Clean the surrounding area if needed. Then, locate and remove the spark plug.

Engine won’t turn over, locked up? We show how to diagnose and Repair a Briggs and Stratton

Now inspect the spark plug and if it looks darker and dirty, use a wire brush or a spark plug cleaner to clean it.

Note: Never use a shot blaster or abrasive to clean your spark plug.

Be careful not to damage the porcelain insulator around the electrode during cleaning.

Next, use a spark plug gapping tool to check the spark plug gap and if it needs a bit of adjustment, do that.

However, if the condition is too severe, replace the spark plug.

Also, check the spark plug lead with a spark plug tester or multimeter, and if required, replace the spark plug lead.

Battery Connection Error

A bad/dead battery, corroded battery links, or connections can also lead the mower to experience similar issues.

riding, mower, engine, seized, lawn

A similar problem will gradually occur if the battery cables or connector become loose from their connection.

How to Fix

Check whether you have left the key in the “on” position because a fully charged mower battery can discharge within 25 hours if you leave the key in the On (S) position.

Make sure the engagement lever is disengaged. Ensure that the PTO switch is in the off position.

riding, mower, engine, seized, lawn

If the lawn mower is still struggling, thoroughly inspect the battery and take necessary action.

If you notice loose or disconnected cable connections, securely tighten them. If the cables have worn out, replace them.

Clogged/Damaged Air Fuel Filter

Over time the air and fuel filters can get dirty or clogged due to abuse and excess built-up debris.

Damaged filters can prevent the mower engine from functioning properly. As a consequence, you will eventually witness turning over failure.

How to Fix

The air filter is the plastic or metal part residing near the mower’s engine compartment, but based on model design and brand, air filter location on a riding mower can vary.

So, verify the accurate location with the help of your mower’s user manual.

Based on the severity of the air filter, either clean or replace the air filters.

Similarly, remove the fuel filter to inspect its current state. If the fuel filter looks extremely clogged, or you see stretched/torn holes in the filter, replace the fuel filter.

Note: Fuel filters should be serviced and replaced annually to prevent such commotions.

Faulty Solenoid Starter

Even a defective solenoid and faulty starter can gradually lead you to encounter a similar problem.

Most Common Riding Mower Engine Problems

Especially when you are sure there’s no issue with the fuel, filters, spark, and battery.

How to Fix

First, take a multimeter to perform a Volt DC test and a Continuity test of the solenoid to find out its current condition.

While testing the existing solenoid, if you can’t hear a click or notice that the solenoid ground looks bad, replace the solenoid.

Seized-up Engine Blades

After confirming that all the major parts are in perfect working state, including the battery and starter, if you still notice a struggle during turning over, it means the engine blades are badly seized up.

– How to Unseize Engine Blades

Get access and manually push on it until you are sure that the motor is free and bound up as required.

Remember not to push too firmly or hard. Otherwise, you might break the engine blades since those are plastic.

How to Turn over an Old Lawn Mower

Here is a simple and quick step-by-step tutorial to make your old riding lawn mower run like brand new:

Maintaining a beautiful lawn can be a daunting task, especially if you lack the appropriate know-how and tools to handle the challenges that may crop up. Fortunately, LawnAsk is here to offer you an all-encompassing resource that covers everything you need to know about lawn care.

Recent Posts

What Happens If A Lawn Mower Has No Oil? (Hint: It Isn’t Good…)

Many of us have heard the dreaded engine knock at one point or another, whether that be with a car or a mower.

If you haven’t I hope you never do!

It often signifies one thing, which we are going to explore in this blog post:

What happens if a lawn mower has no oil?

What Happens If A Lawn Mower Has No Oil?

The most common consequence of running a lawn mower without oil is a completely seized engine, that will not work again. Though on some occasions if a mower is run with oil for just a few seconds, you might be able to get it working again. Otherwise, the lack of oil will quickly increase friction, increase heat and increase wear on the engine, none of which are good.

Before we dive into the dangers of running a lawn mower without oil, it is important to understand the exact role of oil in an engine.

Whether your mower has a two-stroke or four-stroke engine, oil does largely the same job.

  • It lubricates the moving parts of the engine, so they can move smoothly and without friction.
  • The smooth operation of the engine means it stays cool.

And in a nutshell, that is it.

#1: Metals Parts of the Engine Will Rub Against Each Other

As you have probably guessed from our discussion above on the importance of oil, without anything to lubricate them the metal parts of an engine will rub up against each other.

Most significantly the piston rings will wear and warp and most likely fail.

But in general, with parts grinding against each other due to the lack of oil, small metal pieces of various parts of the engine will eventually break off.

These broken bits could clog other engine parts.

And the once smooth and perfectly shaped internal parts will become jagged, broken and abrasive.

And as they continue to rub up against each other without oil, the damage in the engine will become more severe.

#2: The Temperature in the Engine Will Increase

The lack of oil and increase in friction means one thing, the temperature inside the engine will increase rapidly.

Parts of the engine will likely being to melt and weld together.

#3: The Seals and Gaskets Will Melt

The excess heat will also cause the seals and the gaskets within the engine to melt.

These seals are what keeps the oil in the engine in the first place. As your engine gets lower in oil, the temperature will increase, the seals will degrade and any oil left will quickly escape from the engine.

#4: The Engine Will Seize

And this is what it results in.

A combination of all of these factors will lead to the engine seizing and the blades stopping spinning.

The damage is likely to be permanent and the result for you will most probably be a new lawn mower.

An engine can temporarily run without oil.

Sometimes there is enough residual oil left on the walls of the cylinder, or at the bottom of the crankshaft thanks to gravity, for it to start up.

But if you run any engine without oil, it will not last for long…

Lawn Mower Low Oil Symptoms: What You Need to Be Aware Of

If you have got this far in the article, then you probably already have a good idea of what is a sign your mower is out of oil, but just in case you aren’t, these are some telltale things to look out for:

riding, mower, engine, seized, lawn
  • NoiseIf your engine makes a knocking or grinding noise when you turn it on, or whilst you are running it, then turn it off immediately. Irregular noises from your engine are a sign it needs its oil topping up.
  • OverheatingAs we have already established lack of oil means increased friction and increased heat. If you start to feel any abnormal heat coming from your mower turn it off immediately.
  • SmokeSmoke coming from anywhere or anything (apart from a fire!) is not a good sign! Smoke coming from your mower can actually signify either too much or too little oil, neither of which are good. Black smoke from the exhaust pipe usually means too little oil, whereas bright white or blue-colored smoke means too much oil. Either way stop mowing immediately.
  • Your Mower Stops RunningIf you get this far you may have gone past the point of no return already! If the engine seizes completely and the mower stops running check the oil level as that is often the cause. If it isn’t you may have another problem which could be less serious.

What Should You Do If You Accidentally Run Your Mower Without Oil?

Running a lawn mower without oil for anything more than a few seconds is often very damaging to the engine.

In all honesty, the likelihood is that the engine will have seized and you might need a new mower.

That said, in some instances, you can bring your mower back from the brink of death with a bit of luck and some tlc.

Check on your oil levels at regular intervals as it is much cheaper to buy a can of oil than it is a new lawn mower!

What Happens When There’s Too Much Oil in a Lawn Mower? How to Drain Excess

If you buy something through our posts, we may get a small commission. Read more here.

It’s crucial to maintain your lawn mower to give you clean and consistent cuts for your lawn. And when it’s time to do some mowing, you may have added excess lubricant than you ought to on the oil tank.

What if you spilled too much oil in a lawn mower? Here are expert tips our seasoned landscapers and gardeners could do.

Signs that Your Lawn Mower Has Too Much Engine Oil

Firstly, you should check the mower’s engine components to ensure they are functioning correctly. Our experts have compiled a list of common mistakes people make, such as adding too much oil to the lubricant tank.

#1: Engine Seal Damaged

Excess oil will cause malfunction and damage to the lawn mower engine seal. This usually happens when the lubricant passing through the oil filter is too hot, so be careful not to overfill.

#2: Overheating Engine

An overheating engine is one of the most common problems in riding mower caused by adding too much oil than the recommended oil requirements for your mower.

When the oil is too hot, it can cause the lawnmower engine to surge or seize up and not work correctly. In addition, too much oil can damage the seals, gaskets, and combustion chamber. At worst, the engine may even catch on fire.

#3: Locked Up Engine

Your lawn mower may become hydro-locked if you’ve spilled too much engine oil.

This is where there’s oil overfill, causing the engine to no longer run. If this happens, you may need to take your lawn mower to a repair shop to have the excess oil removed from your mower.

#4: Smoking Engine

Another common problem caused by too much oil is a smoking engine. This usually happens when the oil is overheating, causing a lawn mower to blow white smoke from its combustion chamber.

#5: Malfunctioning Engine

Adding extra oil may result in problems with the spark plugs, fuel injection system, or other engine parts, causing the engine to malfunction.

Another sign of a damaged or bad engine is when the crankshaft repeatedly strikes bursting oil during operation.

If you notice any of these problems, we suggest you take your lawn mower to a repair shop to have it checked out for engine block. Stop using your current engine oil and evaluate for compatibility.

#6: Damaged Part/s

Check if your lawn mower shows signs of oil leak and inspect for damaged gasket or spark plug wire. This can be caused by overfilled oil tanks.

What Should I Do If I Added Too Much Oil to my Lawn Mower Engine?

It’s essential to know the signs of too much oil in a lawn mower particularly when readying your mower for the summer, so you can do proper oil removal and refill.

A distinct burning smell or even fumes coming from your engine is a result if you’ve spilled too much oil. It is especially true if you don’t regularly change your oil and the residue has built up.

If there’s too much visibly, you can start by removing the oil dipstick or cap first, then drain. Place enough oil and don’t exceed the maximum mark. Also, clear the oil drops around the engine and air filter as a preventive measure.

If you notice leaks from the engine, this can also be a sign that there’s too much oil in your lawn mower. If this is the case, you need to clean the leaking oil running down its side.

A low-level hum from the engine or even white smoke coming from it can indicate too much lubricant. Our experts recommend you observe this as part of preventive measures against fire hazard.

It’s important to identify and address these signs to prevent overheating your machine and avoid extra cost in repairs and maintenance. It would also be beneficial to check for equipment reviews from others who purchased the same brand.