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Lawn Mower Overheating | Causes and Solution

There are a few reasons as to why a lawn mower overheating, these are generally related to heat being unable to escape from the mower engine block. One solution is leaving the mower in a cool place and leaving it until it cools, but the best solution is to find out what caused lawn mower to overheat and fix it. I will now talk about these problems in detail:
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Lawn mower overheating symptoms

  • Black smoke
  • Backfiring under load 
  • The mower engine dying when giving it gas
  • The engine will lock up or shut down

Cause of Lawn Overheating and How to Fix it

1. Cooling fins are blocked.

The small combustion engines lawnmowers use produce heat as a product of internal combustion. Cooling fins are built into the engine block, near the spark plug, to create more surface area and allow more heat to escape. However, if dirt or grass collects between these fins they create an insulating blanket and trap heat, which eventually causes lawn mower overheating.


Wait until the mower has cooled down and brush away any debris around the cooling fins, do this periodically to stop this problem from reoccurring.

2. Clogged air intake manifold.

Engines require a mixture of petrol and air to run efficiently. If the air intake manifold, this is the tube that runs from the air intake to the carburettor, is clogged with debris the engine will not be getting enough to air and the mixture will be too rich in fuel. This causes the engine to run inefficiently and increases it to produce more heat. Black smoke will be a symptom here.


Clean or replace the air filter and make sure the manifold is clear of any debris.

3. Engine oil level

Incorrect oil levels in the engine can also cause lawn mower overheating. Oil is important for lubricating the piston, crankshaft and other internal components. If the level of oil is to low then there is increased friction between these components, causing the engine to overheat. On the other hand, if the level of is too high there is also a problem. If there is too much oil in the crankcase then is necessary for lubrication then the engine has to work harder and this produces more heat than the engine is able to handle and causes it to overheat


Maintain the oil level recommended for your mower, this is usually found on the dipstick. When adding oil use the correct viscosity, or ‘thickness’, described in the owner’s manual.

4. Engine operation

Lawnmowers are designed to run at full throttle to allow them to push through the grass. Running the mower at less than full throttle for extended periods of time fails to supply it with enough power to do its job. This puts stress on the engine and can cause it to overheat.


Run the engine at full throttle, this ensures that all components work correctly.

5. Engine is overwhelmed

Using a lawnmower in thick, wet grass for a long period of time can cause a lot of stress to the engine. This extra stress can cause the engine to overheat.


Allow grass to dry out thoroughly before cutting it.

Overtime an engines internal components may need to be replaced or even just cleaned, to ensure your engine doesn’t overheat, regularly take it to a service professional who is trained to work on small engines.

Happy mowing!