Lawn Mower Engine Will Not Start When Hot

You’re going on with your lawn mower, doing business as usual, and stop for a quick cup of water or your neighbor stopped to say hi, so you had to stop and hi back at them.

Once you get back to mowing, the Lawn Mower Engine will not start when hot. Try again, but nothing!

Unfortunately, having a malfunctioning mower is a major cause of discomfort.

However, this guide on Lawn Advisors shall provide you with the most known causes for when a Lawn Mower Engine Will Not Start When Hot.

Following those fixes are easy-to-do fixes at Lawn Advisors, to help you with the problem as soon as possible.

Follow the instructions, and hopefully, you won’t need to hire a professional who’ll cost you much to fix it.

What Potential Damage Can a Heated Engine Do?

When the engine heats up, the potential for damaging other parts of the mower skyrockets according to our testing at Lawn Advisors.

It heats up the mower’s ignition system and affects the engine’s metal tolerance as heat makes the metal’s size larger to an extent.

Additionally, when you forget to adjust the choke system in the lawn mower properly, it’ll considerably affect the system.

Some mowers have a fuel tank located near the engine, and a heated engine can make the fuel hotter to an extent too.

Lawn Mower Engine Will Not Start When Hot

Lawn Mower Engine Will Not Start When Hot … What Are The Causes?

There is a handful of possibilities that can cause a heating engine, and the main possibilities include:

1. Overheated Engine

2. Faulty Carburetor

3. Low oil level

4. Spark

5. Air Leaks

Other potential possibilities include:

  1. Failing coil
  2. Plug faulty
  3. Engine flooded
  4. Plug wire faulty
  5. Auto choke faulty
  6. Compression
  7. Valve fault

In this Lawn Advisors guide, we’ll focus on the main possibilities, and how to fix each one if encountered.

1. Overheated Engine

Lawn Mower engines are known to be smaller-sized engines compared to other machinery, and those smaller-sized ones produce more heat.

Therefore, it’s made with cooling fins that have the sole purpose of dissipating the heat, so it doesn’t overheat on a normal day of operation.

However, debris on the lawn can sometimes get clogged in one of the fins, causing the heat to overcompress inside the engine.

This doesn’t always have to be the case, sometimes it’s just grass clippings doing the clogging.

How to fix an overheated engine with clogged fins? Unveil the engine’s plastic cover, and use an air compressor to remove the grass and debris clogged inside the fins.

This shall re-open the path for the fins to cool the heat of the engine.

2. Faulty Carburetor

A faulty carburetor can also be a reason behind your hot engine refusing to kick start again.

What does a faulty carburetor do to the engine?

a. Engine doesn’t get enough air:

With a faulty carburetor, you’re most likely going to have an engine with less air required for its kick start. 

You’ll need to clear the engine’s air filters and chokes, so it regains its normal airflow required for a proper engine kickstart.

b. Engine doesn’t get enough fuel:

This issue surfaces with auto-choke carburetors, as they provide more fuel as the engine gets hotter, leading to flooding the spark plug with fuel.

A flooded spark plug can hardly get the engine going.

To fix it you’ll need to check the carburetor type and get it cleaned properly.

3. Low Oil Level

You may have not heard this before, but specific lawnmowers suffer from engines that won’t kick start or restart whenever the oil level is less than a certain level.

It’s not designed to harass you, no. It’s designed to protect the engine from the errors caused by low oil levels.

Additionally, some engine parts are most likely to stall when the whole engine suffers from higher temperature levels.

The solution is pretty simple, make it a side chore to check the oil level whenever you fill the lawn mower with fuel.

4. The Spark

The spark plug’s main task is to provide a path to ground the high voltage so that the spark ignites. Whenever this process fails, then the mower engine won’t start.

If Spark is the problem, then you’re facing the easiest problem to solve. All you got to do is get a new spark plug at the start of each new season, as they can easily last the whole season.

Moreover, it’s always better to have a spare plug, you’ll be able to troubleshoot, and fix the the issues on spot.

5. Air Leaks

If the engine suffers from air leaks, it means that the bolts are too loose that the engine will forcefully suck in more air than needed, creating a disbalance in the gas-to-air ratio required to kick start the engine.

How do the bolts loosen up? When the engine heats up for longer periods of time, the remote parts will expand naturally, and the gaps become larger and larger, creating such air leaks.

How to fix that? Create a schedule where you tighten the bolts whenever possible, and check for other engine parts in the process.

Lawn Mower Engine Will Not Start When Hot FAQ


When you face a problem of a Lawn Mower Engine Will Not Start When Hot, all you need to do is wear your safety outfit, get the right equipment, and start troubleshooting the aforementioned problems.

Those are made so you can fix the problem yourself. If you’re not familiar with the lawn mower parts and how to deal with them, we advise you to call a specialist and get them to solve it for you.

Do you have any other questions related to the Lawn Mower Engine Will Not Start When Hot problem? Leave them in the comments section below and we’ll answer them ASAP.

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