Lawn Mower Left in Rain Won’t Start- What To Do?

Last Updated on April 3, 2024 by Sharaj

Can you predict the weather? Well, it’s the primary reason for some mechanical failures, and one of them is related to your lawnmower.

Sudden rain is the primary reason for an outdoor tool to get wet. The mower can be exposed to a shower if you left the unit outside and it starts raining.

After such an incident, most of the users thinks that their mower is damaged.

Yes, we agree that the mower can turn into a scrap after its exposed to moisture, but it’s not the case every time.

Today, we will see what happens if a lawn mower gets rained on. We will also discuss some steps to repair the mower if it’s wet and causing problems.

What Happened If My Lawnmower Gets Rained On?

A lawnmower’s motor is safe inside a moisture-resistant case, which can be plastic or metal made. It’s easy to understand the thought behind such an arrangement.

However, this waterproof casing cannot protect the motor from heavy rainfall. Do you know why?

Most motor casings comprise small vents to maintain airflow and avoid any overheating when the mower is operational. Water can reach the motor via these holes and damage its internal components and wiring, especially if the mower is exposed to rainfall for a long time.

The mower’s battery also sits inside a waterproof case. However, its cover has hinges that allow you to take out the cell. Water can follow these connection gaps to reach the battery and damage it.

Moisture will also corrode the battery connections interrupting the supply of power to the motor.

Overall, your lawnmower might run with a dim power or will not start at all after it gets rained on.

What is the solution? You need to realize that the lawnmower is wet, and hence, you need to follow the drying process.

How Can Condensation Damage Your Electric Mower?

The lawnmower is not entirely safe, even if you live in a region that experiences minimal rainfall. Do you know why? Temperature fluctuation is the answer. We all know the temperature drops at night, which can cause moisture condensation inside the water-resistant case of the battery and motor.

To ditch the moisture and add some more years to the mower’s life, you need to store it inside a garage. In case you don’t have access to the garage, then investing in a weatherproof garden shed might be a bright idea. You can store the mower and all other outdoor tools inside such a shed.

You should also take a look at the condition of grasses before deploying a lawnmower over them. In case the lawn is wet, you should wait for it to dry.

How Can Short Circuit Damage Your Mower?

When an excess amount of current is supplied towards the wrong connection in an electrical system, it might lead to irreparable damages. This short circuit situation arises due to water exposure, and it can damage the lawnmower’s motor. You might notice white smoke from the motor as it’s burning internally. It happens because a massive amount of charge is passing through the motor.

Such smoke can result in a fire if you don’t shut it down immediately. If you think that the mower is wet, then do no try to switch it on.

Steps to follow when your lawnmower was left out in the rain for long.

  • Take out all the covers of the lawnmower and expose its motor.
  • Let the motor and its wirings dry.
  • Use an electrical contact cleaner to clean all the electric components.
  • Water can negatively impact the motor’s insulation resistance. Use a megohmmeter to test and rebuilt it.

Whether it’s a mains powered, gas propelled, or battery powered lawn mower left out in rain, you need to act as fast as possible to save the machine from being damaged. So, it’s essential to know how to dry such devices.

How to Initially Dry The Lawn Mower?

You can save the mower from moisture using a blow drier, high-pressure air blower, or a fan. Afterwards, you can leave it under direct sunlight for some time. Consult the user’s manual to know how you can take out the water-resistant covering around the motor.

Drying a mower will not be a quick and straightforward task if it was left out in the rain for a prolonged period. So, it’s best to take out the waterproof casing and let it dry for as long as possible. Depending upon the severity level, the mower might be completely dry within 8 hours or even more.

Once the mower is dry up to some extent, we recommend that you apply an electronic contact cleaner. Please put it on the battery’s terminals and all other electrical connections. If you don’t have immediate access to a contact cleaner, try a lubricant or grease. You need to ensure that all the links are clean and free of moisture.

If the wires have lost their insulation due to extra water, then you can use a device called a megohmmeter to check the existing resistance. This device will let you know whether you need to follow further steps to dry the wires.

The situation changes if you had a gas lawn mower left out in rain. In the case of petrol or gas propelled mower, you need to take out its spark plug, carburettor, crankcase, air filter and let these parts dry for some time. You need to follow the instruction manual and follow the given disassembly instructions to remove all these components.

In a situation where the petrol mower is slightly wet, you don’t have to take out all its parts. Instead, focus only on the spark plug, dry it and reinstall. Take out the air filter, put some starting fluid into the air intake and start the engine. The engine will make spitting sounds if its fuel is free from any contamination. If it does sputters, then repeat the process until the engine starts properly.

How to Restore The Insulation Resistance of the Internal Wiring?

Once the mower is dry, especially it’s motor and wirings, you must restore the wires’ insulation resistance. The mower will be unsafe to use without any insulation resistance. Keep in mind that even a tiny amount of current can destroy the battery if it’s wet.

So, your first step is to use a megohmmeter and measure the resistance insulation of the motor’s wiring. Keep measuring until you see 100,000 ohms of resistance value on the device. If the value is below this number, then the wires are not dry, and you need to wait. Once you read the correct digits, the next step is to run a small amount of current via the motor.

Check the instructions manual to know the right amount of current. In case you lost it, check the make and model of the lawn mower left in rain. Go online and download the required manual using these details. Once you have the document, look for a term nameplate voltage. It’s the range of voltages that the mower’s battery can operate.

Apply 10 per cent of nameplate voltage to restore the insulation resistance of the motor’s wiring. Repeat the process until and unless you see the correct value, which is 100 000 ohms. Check the numbers every time after you apply the current.

You need to replicate the same step several times to get the correct output. So, it’s better to work patiently. If everything goes good, the mower will be up and ready to take on the next maintenance task.

Frequently Asked Questions

Can lawn mowers get wet?

Lawnmowers are designed for outdoor usage, and a small number of sprays will not make any difference to them. But, if the moisture gets inside its motor or battery, the results will not be pleasing.

Are lawn mowers waterproof?

None of the lawnmowers can be completely waterproof. They can be water-resistant, but large quantities of water will still damage them. So, small showers might not make many negative impacts on complex outdoor machines like a mower. But, the lawn mower won’t stay running if its exposed to heavy rainfall that also for a prolonged period.


Now you know what happens when the lawnmower gets rained on. So, it would be best if you store the lawnmower inside your garage or garden shed so that it can stay safe from unexpected rainfall and condensation. By chance, it gets exposed to water; then, you need to follow the steps we discussed today.

If you are a beginner, you might not be able to deal with the motor drying process and restoring insulation resistance. So, contact a professional who can do the needful. It’s best to contact the manufacturer or the shop from where you purchase the mower.

In case your lawn mower left in rain won’t start even after repair, then you need to try a new one.

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