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Can Riding Mower Get Wet? Don’t make this mistake!

Hey, I’ve done it dozens of times, took a break from mowing, and forgot to put the mower away…now it’s properly wet. And so your next question is a fair one, we leave our cars and trucks out in the rain, so what’s the deal with riding mowers?

Riding mowers are weatherproof, leaving them outside in a medium-size downpour won’t cause any major issues. However, riding mowers are not waterproof and power washing them indiscriminately may cause fuelling, ignition system, and bearing issues.

By the end of this post, you’ll understand how a heavy downpour or careless power washing can harm your pride and joy. But I’ll also share a few insider tricks to help ward off water damage.

Riding mower in rain

Riding Mowers and Rain

A little spring shower won’t hurt your riding mower any, that said if you are in the habit of leaving your mower outside year-round. Well, that’s a different story. As a mechanic of over twenty-five years, I can tell you, mowers that live outdoors don’t live as long. Not only that, they break down more often, and surprise surprises cost a lot more to maintain.

What type of problems does Rain Cause a Riding Mower?

The problems rain causes mowers depends largely upon how long a mower is left out in the elements. Problems generally fit into one of three buckets:

  1. Rust
  2. Ignition system dampness
  3. Fuel system contamination

And as you already know, a mower that sleeps outdoors will suffer the most, it will likely suffer from all three of the above.


The problem with rust is it forms everywhere there’s metal. While a mower isn’t complex it does employ a ton of metal levers pulleys, gears, bearings, etc. Not all of these components are visible or easily reachable for cleaning and lubing, however, water doesn’t have any trouble finding them.

When rust forms on the metal drive and deck pulleys, it contaminates expensive kevlar belts, and that in turn may cause drive slip and deck vibration. Some light pulley rust is normal and is cleaned by the rotating belt, but heavy rust build-up on the unloved outdoor types transfers to the belts and the only fix is to replace the belts.

In addition, corrosion caused by rain to brakes, steering, and bearings is common. But the rust fun doesn’t stop there, many decks are raised and lowered by a series of levers and springs pivoting on pins to aid easy and accurate deck level adjustments. Rust causes the pins and levers to bind resulting in lawn scalping and blade damage.

The fix – spray components with WD40 and regrease all the pivoting metal components with copper grease.

Ignition System Dampness

The ignition system is as you know responsible for generating a voltage strong enough to jump the spark plug electrode. Water and electrics don’t agree, allowing a coil to get wet can cause it to short, meaning it will need to be replaced.

That said, riding mower coils are pretty well protected from the elements. The coil lives under the engine blower housing and of course the hood offers additional rain protection.

The fix – use WD40 to drive out dampness

Fuel System Contamination

Water in the fuel system is common among mowers, especially after the winter hibernation. Heavy rain coupled with a poor-fitting or faulty gas cap vent will allow rainwater to enter the tank. As oil floats on water, it’s not long before the engine stalls.

The fix – check the gas cap for fault, drain the carburetor bowl and add a gas stabilizer to the gas tank. Check out adding a gas stabilizer video here.

Power Washing A Riding Mower

Power washing a riding mower regularly is generally not advised. Although a nice clean mower looks great, it can cause serious issues. Power washers are pretty powerful these days, even electric household versions are capable of removing critical component grease and blasting water into sealed bearings.

Problems arise when water gets into sealed bearings and can’t get out. This results in premature failure of the spindle, belt pulleys, and wheel bearings.

I prefer to clean down a mower deck using the deck wash-out port and old-fashioned elbow grease. You can check out a wash-out port and tools I use here.

However, if you’re sensible with the pressure level and avoid the critical areas it’s fine to use a pressure washer. Avoid washing the engine, electrical components, around bearings.

Symptoms Of A Wet Riding Mower

Symptoms of a mower include the following:

  • Won’t start after rain – possible wet coil, plug wire or spark plug
  • Engine starts but stalls – possible fuel contamination
  • Engine runs but misfires – possible fuel contamination or damp electrical system
  • Engine won’t idle – possible fuel contamination or damp electrical system
  • Engine flooded – possible fuel contamination or damp electrical system

How To Dry Out A Riding Mower

If you have just washed your riding mower or it’s been sitting out in the rain for then it’s likely your riding mower ignition system is damp or wet.

If on the other hand your mower has been sitting outside for longer than a couple of days and won’t start it may suffer from gas contamination.

To dry out a wet ignition system – A wet spark plug and plug wire is easy to spot. The coil isn’t visible but the plug and plug wire are and that means they are easy to dry. To dry the plug go ahead and remove the plug wire from the plug and use a kitchen towel to dry inside the plug wire cap plug and wire. Coat liberally with WD40 refit wire and attempt to start the motor.

Spark plug

If the mower fails to start, try removing the spark plug and use a naked flame like a gas lighter or a cooker hob flame to burn off plug contaminates. When an engine refuses to start initially the unburnt gas in the cylinder saturates the spark plug.

How To Protect Riding Mower From Rain

The best protection from rain is obvious – avoid cutting grass or leaving the mower out in the rain. But if that isn’t possible then try this. On a dry day warn the mower engine and coat the whole mower with Teflon coating or WD40. Both help repel moisture. In addition, you can use car wax on the mower’s body panels. Wax will last longer and offer better paintwork protection.

Riding Mower Storage Tips

Storing a riding mower over winter isn’t difficult, I’ve covered it in a bit more detail here – “Lawn mower winter storage”. But even doing just the basics is enough to help your riding mower survive the winter hibernation unscathed.

The basics include:

Use a battery maintainer – the smart battery charger charges the battery as needed so it’s a plug-and-play tool. I’ve listed the smart charger I recommend here on the “Small engine tools page”.

Fill the gas tank – a full gas tank leaves no room for moisture to for on gas tank walls

Use a gas stabilizer in the fuel system – adding a fuel stabilizer keeps the gas fresh over the winter and repels moisture,

Spray WD40 – Warm the mower and on a dry day coat the whole mower with WD40, coat the engine, electrics, deck, and the body, Avoid spraying belts and pulleys. WD40 forms a barrier that protects from moisture, dirt, and corrosion.

You may find the following posts helpful:

Lawn mower video repair library

Mower winterizing

Can I hose off my mower?

Are gas caps universal?

Can you cut grass in the morning dew?

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