Older man fixing a lawn mower.

Lawn Mower Won’t Start Until It Cools Down – Causes And Solutions

4 minutes

It’s never a good thing when your lawn mower won’t start. Sometimes this can be because it just needs to cool down. In this article, we’re going to go over several reasons why a lawn mower won’t start until it cools down as well as what to do about it.

Lawn Mower Won’t Start Until It Cools Down – Our List Of Causes And Solutions To Fix Them

There are several reasons why a lawn mower might heat up.

Let’s start with the cooling fins.

Cooling Fins

Closeup of a person working on a lawn mower engine.

Engines get hot. This is even more true on hot days. Thankfully, the people who design and build engines know this, so they’ve equipped them with something called cooling fins.

Cooling fins are an essential part of keeping a lawn mower cool. Unfortunately, these fins can become clogged with grass, dirt, or other debris that works its way up into them.

What To Do

Thankfully, this is a simple fix. All you need to do is to regularly clean the cooling fins. We recommend doing this at the end of every season during your end-of-season lawn mower maintenance.

Oil Is Too Low, Wrong Kind, Or Too Old

Closeup of someone pouring oil into a lawn mower.

Lawn mowers, like cars, depend on oil to run well. If there isn’t enough oil in the lawn mower then the parts that need that oil won’t be lubricated enough. This leads to friction, which causes heat.

This is also true if your lawn mower has the wrong kind of oil or if the oil hasn’t been changed in a long time. So, what can you do?

What To Do

The solution depends on the problem. If there isn’t enough oil in the lawn mower and it hasn’t been too long since you last changed the oil, add more oil. If the oil is old, then it’s time to change it, and if the oil is the wrong kind, it’s also time to change it.

Air Leak

Closeup of part of a lawn mower engine.

Although it’s unlikely, an air leak in a lawn mower can mess up the internal workings of a lawn mower to the point it won’t start. How is this possible?

Well, if outside air is leaking into a lawn mower, this is likely because some bolts are too loose. Tightening them should fix the issue. What happens is that the outside air messes with the proper mix of gasoline and air that a lawn mower needs to function.

When this happens, the engine will heat up as it normally does, but now parts and gaps are going to expand beyond normal. As a result, the lawn mower shuts down and won’t start back up.

What To Do

In this case, you’ll need to find the bolts that are causing the issue and tighten them.

Air Filter

Closeup of somebody working with a lawn mower air filter.

If your air filter becomes too clogged with grime, dirt, or grass, this can reduce how much air gets to your engine. In turn, this can cause your engine to overheat and even shut down.

What To Do

If the air filter is the issue, you can either clean it or replace it.

Other Ways To Keep A Lawn Mower Cool

Here are some other ways to keep the lawn mower cool.

Clean The Lawn Mower

We recommend cleaning your lawn mower regularly. At the very least, clean it before the season starts and then after too. You don’t have to do a deep clean every time, but keeping it free of dirt, grass, and grime, helps it to run better.

Get Professional Help

Sometimes it’s a good idea to turn to the professionals. If your lawn mower still isn’t starting until it cools down or if you’d like a second opinion, there are plenty of people out there who are able to help.

In Summary: Lawn Mower Won’t Start Until It Cools Down

So, now you know a few reasons why your lawn mower won’t start until it cools down and what to do about them. This should make your mowing season a lot more enjoyable.

So, ever had your lawn mower shut down on you? What was the reason and what did you do? Let us know in the comments below!

Todd L Miles
Lawn Mowers Enthusiast
I started "Landscape and Lawns Care" to provide clients with lawn care with better service, better products and, most importantly, better ethics. My promise to every customer is to give the greenest grass possible while controlling weeds, insects, and diseases! The most important thing is that I strive to always do the right thing for you, your lawn and your wallet!