Why Does My Lawn Mower Get Overheat And Die?

Sometimes it is puzzling when a mower starts easily, runs fine, and all of a sudden stops without a warning. This can happen as the lawnmower engine burns gas inside the cylinder, it generates an enormous amount of heat. 

If the heat could not disperse out of the engine to maintain the proper pressure for all the moving systems on the mower, too much heat can build up. And when your lawnmower will get overheated, the blades of the mower will stop spinning or die. 

If you run an overheated mower for a long period, this can damage engine’s internal components. So, you need to figure out why the lawnmower overheats and dies and know how to cool down a lawnmower to avoid these issues.

What Happens When A Lawn Mower Overheats?

The most important sign of recurrent overheat of the engine is the parts of the engine get damaged.

The blocked cooling fins are one of the causes of getting overheated. Since all the grass and debris from the yard can easily end up in the cooling fins. It can keep the air from circulating and cooling the engine. 

Some causes of electric lawnmower getting overheated are blocked air vents, clogged cutting deck, too low cutting height. For the gas mowers, clogged air filters, insufficient engine oil and more – are the reasons of overheat.

The Causes And Solution Of Overheating And Death Of The Mower

If you encounter the following symptoms, you can assume the causes and take action.

Engine Issues

There are some reasons when the mower doesn’t start when gets hot.

Air leaks can cause an engine to pull in too much outside air that can throw off the gasoline-to-air ratio.

So, when the engine heats, the parts get expanded and all the tiny gaps get larger. This results in a poorly running engine which eventually stops. 

Vent Issues

One of the customers said that his mower had got overheated and shut off for vent on the gas cap.

If it is blocked, it will run until a vacuum is formed in the tank and then it starves out.

Again, loose bolts are also the reason which causes the mower engine to get shut off.

After sitting a while, air will seep in and equalize the pressure. If you loosen the gas cap, the problem will be solved. 

Moisture And Other Fuel Line Trouble

Moisture can prevent proper ignition when it enters the engine as oil and water don’t mix well.

For the ill-fitting gas cap, moisture can enter the system. This can warm up the temperature of the engine and the engine sputters and dies. 

The best solution to overcome this issue is to drain mower’s gas tank and refill it with fresh gasoline. 

Clogged Fuel Filter

A clogged fuel filter also causes a mower engine to die. The reason is debris caught in the bottom of the gas tank can plug the fuel line where it exits the tank. 

You need to change the fuel filter. It will also reduce moisture issues.

Dirty Air Filter

A dirty air filter can restrict proper airflow into the engine. A proper filter is needed to pass the cool air for combustion.

So, you need to clean it every eight hours of operation.  

Carburetor Issue

A carburetor establishes the correct mix of fuel and air required for smooth mower operations.

The springs, floats, needle valves, and spray jets of this part can clog or need replacing.

A lean carburetor mixture that means too much air and not enough fuel can cause an engine to overheat even with plenty of cooling air. 

Again, deposits are built up along the hoses and inside the carburetor which can gradually choke off fuel arriving in the carburetor. 

Setting The Cutting Height Too Low

If the cutting height is set too low, the mower has to work hard. And it is a common cause of overheating.

You need to set the height properly. 

The Blade Is Loose Or Bent

If the lawnmower blade is loose or bent, it won’t be capable of cutting the grass properly. The wiggle of the blade will cause the cutting height to change constantly.

When you notice your mower is cutting unevenly, you will know that the blade is loose.

Since the cutting efficiency is worse, there’s more strain on the motor/engine, and it could get too hot to function properly.

To solve this issue, you may need to install a new blade or you can simply tighten it up.

Engine Oil Level

Too little oil in the crankcase means too little lubricant for crankshafts, pistons, and other internal engine parts. So, friction can occur as parts move rapidly inside a running mower. And it can cause overheating. 

Check the oil levels when the engine is turned off and the mower is resting on a level surface.

If the level is below the “full” mark, add fresh oil. Ideally, check oil levels after every 20 hours of use, or each time you use the mower.

When adding oil, use the correct viscosity described in the owner’s manual. Too heavy or too light may cause overheating.

Overwhelmed Engine

If you run your riding mower through heavy, wet grass for extended periods, it can cause stress on the engine. This added load can overheat the motor. 

Allow grass to dry in the sun before mowing.

An engine that is not properly tuned struggles to operate and may overheat. A clean mower that overheats when run at full throttle during normal mowing may be ready for a tuneup.

Vapor Lock

The vapor lock, which means the pressure causes the gas flow to reverse and move out of the carburetor.

The engine can’t operate with these heated gases trapped inside the tank, effectively shutting the engine down.

Often referred to as vapor lock, the engine can’t operate with these heated gases trapped inside the tank. 

Damaged Cooling Fins Or Shroud

The cooling fins and shroud are for dispersing heat and moving it away from the mower engine and into the airstream.

But if cooling fins don’t properly direct the heat away, it increases the risk of overheating. So, you need to replace the part to avoid the issue. 

For keeping the cool air around the cooling fins, the flywheel has fins that act as a radial fan.

At the time of running of the engine, these fins bring air in from the shroud and push it around the engine to remove heat.

If anything gathers on top of the shroud, you can face airflow problems. And this can eventually cause overheating. 


The buildup of grass, twigs, and other materials in the engine cooling fans, engine shroud, air intake screen, grille, and/or side panels can quickly lead to an overheating lawnmower.

You need to remove grass clippings from the engine area regularly to prevent this problem.

Or, remove the carburetor, disassemble and clean it thoroughly. Install a carb kit before reinstalling the carburetor.

Low Coolant 

Some lawnmowers use liquid engine coolant to keep the engine from overheating.

You need to check the engine coolant before each use and refill as necessary.

You may also need to do lubrication from oil to prevent overheating. 

How Often Should I Clean My Engine?

There are some rules on how often you should clean your engine.

Most user manuals advise doing basic maintenance and oil changes after approximately 50 hours of use.

If your engine is new, you will need to complete an initial oil change within 7-10 hours of initial use.

You just need to do the following steps: 

  • Changing the oil
  • Changing air filters
  • Adding new spark plugs
  • Check whether there are any rodents in the air paths

If you live in an area where it snows during the winter, it is important to protect your mower during the “off-season” by winterizing your mower. The steps are:

  • Drain your mower of gas or add a fuel preservative
  • Wash off any visible debris
  • Sharpen the blades
  • Remove the battery and spark plug
  • Store your mower in a dry place for the winter
How to fix an overheating mower!


The problems are mentioned above cause the lawn mower overheats and dies. 

The problems which cause a lawnmower engine to overheat and shut down require more extensive maintenance to correct.

You need to routinely check or replace the engine parts as needed, such as shrouds and cooling fins.

Always give 20 to 30 minutes to your mower to get cool down. You can do these maintenance routines by yourself or by taking the mower to a qualified service technician.

If you own a lawnmower in your garden. You will face different kinds of troubleshooting on your mower.