If you’ve been using your lawn mower recently and you’ve felt the heat it’s throwing off when in full flow, you might be wondering “how hot does a lawn mower engine get?” Is this heat the norm, or is there something wrong? These are good questions to ask, since if a lawn mower is overheating, it can do long-term damage to the engine that is expensive to put right.
So exactly how hot should a lawn mower get and what happens if it exceeds those temperatures? That’s what we’re going to talk about in this post.
How Hot Does a Lawn Mower Engine Get?
A lawn mower engine can get extremely hot during operation. The exact temperature varies depending on the part of the engine. On the intake a temperature of approximately 250°F under load is normal. The engine gets hotter on the exhaust side though, with 400°F common when idling and up to 600°F when under full load.
What Affects How Hot a Lawn Mower Engine Gets?
The temperatures that I just mentioned in the previous section are considered to be standard, but the “normal” temperature of the engine on your mower may vary a little bit depending on a few factors. These include:
- The outdoor temperature when you take a reading
- The make and model of your engine
- The type of engine you have (whether it’s air-cooled or liquid-cooled)
- How you run your mower (do you put it under excessive load?)
- The condition your mower engine is in (has it been well maintained?)
These are all variables that can affect the reading when you take the temperature of your lawn mower’s engine, and could potentially drive it above the guide readings that I outlined above.
For example, if your mower has an air-cooled engine (the majority of lawn mowers do) that has poor airflow and has not been well maintained, and then you take the reading on a baking hot summer afternoon, there’s a good chance that the intake will read closer to 300°F than 250°F. Some manufacturers of lawn mower engines are also known to do a better job with engine cooling.
How Hot Does a Lawn Mower Muffler Get?
The muffler is one of the hottest parts of the lawn mower when it’s being used. On a smaller mower, 350°F is a fairly typical temperature for the muffler when running, and that can go up to 450°F for a larger riding mower. It gets this hot because the muffler sits at the end of the exhaust pipe and it is where the exhaust fumes pass through before leaving your mower. Its job is to reduce the amount of noise produced as a result of the engine combustion process, as well as prevent your lawn mower backfiring.
Can you run a lawn mower without a muffler? Sure, it’ll run. But cold air will get inside the exhaust pipe when you shut the mower off, and this can cause the engine temperature to drop suddenly, which can lead to the valves bending and becoming deformed. The only solution is to have them replaced, and that can get costly. So always make sure your mower is fitted with a muffler.
What Can Happen If Your Lawn Mower Engine Overheats?
If you think that your lawn mower might be running at much higher temperatures than those I’ve referenced in this article, it would be wise to check. If a lawn mower engine overheats and you don’t do anything about it, it can have some serious consequences. Any of the following could happen.
- Lawn mower loses power when cutting
- Engine suddenly locks up and shuts off
- Engine components can melt
- Blown gaskets
- Lawn mower on fire
The risks of doing nothing about an overheating lawn mower can be serious, both for your mower and your own safety, so please don’t ignore this issue. It’s not going to go away on its own.
You need to be ULTRA careful when you are around your mower after it has been running. The engine gets very hot (250°F) and the muffler even hotter (350 – 450°F). Touching any of these parts with your bare hands would result in extremely serious burns. I recommend you never try to touch any of these parts until they’ve been left to cool down for a good period of time (30-60 minutes).