If you are asking the question ‘how hot does a lawn mower engine get?’ it could be for one of two reasons.
The first is out of pure curiosity as your mind wanders whilst you cut your lawn, the second is because you are genuinely concerned that your mower might be overheating.
Well, whatever the reason we have got you covered in this article.
We will look at how hot your mower engine can get, what can affect its temperature, the dangers of your mower engine overheating and how to cool it down if you are concerned it is too hot.
So let’s dive in.
How Hot Does A Lawn Mower Engine Get?
The hottest parts of a small lawn mower engine, ie the exhaust, can hit up to 400°F, on a larger lawn mower engine that figure could be higher. A more comfortable operating temperature for a mower is around the 250°F to 300°F mark. If you fear your mower is overheating, stop mowing immediately and, when it has cooled down sufficiently, check nothing is clogging its filters, etc.
What Temperature Does a Lawn Mower Engine Run At?
The temperature of your lawn mower engine can vary wildly for reasons we will go into in more detail later.
But it does depend on the mower, the mowing conditions and a range of other things.
Your mower will always be hottest near the exhaust port too, so expect high readings for a spark plug or muffler for instance.
If you want to know how hot the oil gets in a small engine like a lawn mower, then you can expect it to reach around 250°F.
If you are talking about the cylinder itself, that can hit temperatures of around 300°F to 350°F, possibly bordering on 400°F right near the exhaust port.
Want to know how hot a lawn mower muffler gets? Well we have already discovered it is one of the hottest parts of an engine as it sits right at the end of the exhaust pipe. The muffler might hit 400°F or even 450°F on large lawn mower engines.
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When giving you an answer like this I do always like to do a bit of research to provide you with some details aside from just my own personal experience.
So if you want to know how hot a lawn mower gets, then below is some genuine first-hand experience I found whilst preparing this article, posted in various lawn mower forums:
Person 1
“Mowing in Oklahoma this morning I checked the temperature of my mower. The temperature outside was around 85°F when I was mowing. After an hour of mowing, and having just mowed the thickest patch of my lawn, the oil was 212°F, the block was 168 °F and the drives were 140°F.”
Person 2
“When I mow at around 85°F, my Intek runs oil between 240°F and 300°F. When it gets above 280°F is when I start getting concerned, and if it hits 300°F I stop and let it cool down.”
Person 3
“In my experience (based on a test I did on a Briggs and Stratton 6.5hp push mower engine) most small engines run at 240°F at the spark plug and around 320°F at the muffler/exhaust.”
Person 4
“After about 40 minutes of mowing the filter was 157°F and the lower crankcase, where the oil level would be, was 187°F.”
Person 5
“It was pushing 95°F when I mowed yesterday in Northern Alabama. The oil temperature was around 200°F after 30 minutes, 225°F after 60 minutes and 250°F after 90 minutes of mowing.”
Person 6
“I’ve seen 250°F on my lawn tractor when under heavy operation too. It usually runs at around 225°F when ambient temperatures are 85°F.”
Person 7
“I put an oil cooler on my Intek Craftsman, but it can still get up to around 180°F to 200°F in cold weather of around 25 to 40°F.”
So seven individual accounts there, and they are fairly consistent, so I think we can say from personal experience you can expect your mower to reach somewhere around the 250°F mark.
What Affects the Temperature of a Lawn Mower Engine?
As mentioned previously, and as illustrated by some of the personal accounts above, there are a number of factors that have a bearing on the temperature of a lawn mower engine.
These include:
- The ambient temperature outside. The higher temperature the higher the engine temperature.
- The length of time you have been mowing. The longer the mower has been in operation the higher its temperature.
- The thickness of the grass. Your mower will have to do more work to cut thicker grass and the temperature of the engine will increase.
- The make and model of your mower.
- How well maintained your mower is, ie if particular parts are clogged it could cause the engine to run hotter.
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How Do You Measure the Temperature of a Lawn Mower Engine?
This is a valid question because it can be difficult to get the temperature of something that might be 300°F!
Generally there are two ways to do it:
- Get yourself an infrared temperature gun, then simply aim it at the outside surface of the oil filter. Ideally, aim it at a sticker on the surface of the filter as infrared guns don’t work effectively on shiny surfaces.
- Get an oil temperature gauge or a dial thermometer to read the oil temperature.
The Dangers of Overheating: How Hot is Too Hot For a Lawn Mower Engine?
Based on what we have discussed so far, if your mower engine gets to 300°F you want to keep a very close eye on it.
When it gets to 350°F, you want to think about stopping mowing and letting it cool down, if it creeps up to 400°F then you definitely want to call a halt to your lawn care maintenance for a while.
If your mower engine gets too hot it could lead to blown gaskets, melted parts or, in the worst-case scenario, an actual fire.
It could not only render your mower useless and mean you have to buy a new one, but it could also cause you physical harm.
Be careful!
How to Keep Your Lawn Mower Engine Cool
If you are concerned about your lawn mower overheating there are two very easy ways to deal with it.
Firstly, if you are mowing and you can feel it is overheating, simply stop as soon as possible and park the mower in a safe open place.
Make sure it is somewhere where the muffler can’t come in contact with anything that it might set alight such as brush, paper or cardboard
Then just let it cool naturally until it is ready to start mowing again.
The second way is, when you have finished mowing, check to see if anything is clogging up any of the air passages or various parts of the mower.
Have you ever wondered how lawn mower engines stay cool? Pretty much all small engines are air-cooled.
They have finned cylinders that act as fans. They propel air through the engine to remove the heat that is generated as the fuel burns.
If these fins get clogged up with oil or grass it stops them from doing their job properly and your mower will overheat.
Simply remove the shroud that covers the engine (when it has cooled down obviously) and clear anything out that might be plugging these parts. Blow it out with compressed air if possible.
You will also want to check there is oil in the crankcase of a 4-stroke engine and that the oil is the proper level and grade.
Check your lawn mower blade is sharp and on the right way as well. It is very easy to put them on upside down, and this means the mower has to work harder to cut grass.
Finally you can schedule your mowing to avoid warm days (it is always nicer mowing when it isn’t scorching hot!), and cut your grass regularly to avoid heavy loads that put more demands on the mower’s engine.
Whatever you do DON’T spray cold water on it. The sudden contrast in temperature can crack the mower.
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Final Thoughts
A lawn mower can get very hot, but a comfortable operating range is around 250°F on most small engines as shown by the infographic above.
If it starts getting above 300°F you want to be more careful, and anything above 350°F is when you want to consider stopping and allowing your mower to cool down.
Your engine temperature will vary depending upon the load it is being placed under, the time you have been mowing and how well you have looked after the mower.
But it is something you should pay close attention to as an overheated mower can have potentially catastrophic consequences for your wallet and potentially even your health.
Regularly clean out your mower’s filters and fans as, if they are clogged up, the temperature of the engine will definitely be higher.
In the words of the Fonz, stay cool!