How to get your ride-on lawnmower ready for the new season

Spring is here, the grass is growing, and your trusty ride-on has been sitting quietly in the shed since October – so before you climb on and turn the key, it’s worth taking a couple of minutes to run through a proper startup checklist.
A little attention now can save from a frustrating breakdown mid-season, and save you from a surprising bill on your several-thousand-pound investment.
This guide walks you through the basics, including how to check the battery, tyres, engine oil and coolant, so you can mow with confidence through the season.

Battery

You hop on the seat, turn the key, and…. nothing. Battery issues are one of the most common reasons for starting issues after winter storage. Even if you disconnected it from the mower before storing it, many common types of batteries in ride-ons (particularly lead-acid batteries) self-discharge over time, and a battery that’s sat flat for many months may have suffered permanent damage to its cells, in which case it may be time for replacement.

If you’re in this situation, the first step is to try recharging the battery. Trickle charging is far kinder to a battery than fast charging. A slow, steady charge at a low amperage (typically 0.8A–4A) allows the battery to recover fully without the heat stress that can buckle plates inside the cells.

You’ll need a trickle charger or smart charger rated for 12V lead-acid batteries (most ride-on mowers use a 12V battery). Look for one with an automatic “maintenance” or “float” mode — this means it’ll stop pushing current once the battery is full, so you can leave it connected safely overnight.

When you’ve got an appropriate charger, there’s some simple steps to follow:

• Locate the battery. On most ride-ons it’s under the bonnet or seat, or behind a panel near the footwell. Consult the manual if you’re unsure.
• Check the battery terminals. Look for white or blue-green powdery corrosion on the terminals. A light scrub with a wire brush or a paste of bicarbonate of soda and water will clean this up. Rinse well and dry before proceeding.
• Check the battery case. If the case is cracked, bulging, or leaking fluid, the battery needs replacing. You should not attempt to charge it.
• Connect the charger. Red (positive) clamp to the positive terminal (marked +), black (negative) clamp to the negative terminal (marked −). Double-check polarity before switching on.
• Set the charger. If your charger has settings, select 12V and the lowest available amperage (1A or 2A is ideal for an overnight recovery charge).
• Leave it to charge. A fully depleted battery may take 8-12 hours on a trickle charge. Most smart chargers will indicate when charging is complete.
• Disconnect and test. Remove the charger (negative clamp first), refit the battery, and try to start the mower.

If a full overnight charge still hasn’t done the job, or you need to get the mowing job done today and a charger isn’t available, you can try jump-starting your ride-on. It’s a similar process to jumpstarting a car, and you’ll need a donor battery or vehicle with a 12V battery (make sure it is switched OFF!), or a portable jump pack.

• If you’re using a donor vehicle, position it close enough for the leads to reach, but ensure the two machines are not touching each other
• Connect the red (positive) lead to the positive terminal of the flat battery
• Connect the other red (positive) lead to the positive terminal of the donor battery or jump pack
• Connect the black (negative) lead to the negative terminal of the donor battery
• Connect the final black (negative) lead to an unpainted metal part of the mower’s frame rather than directly to the flat battery’s negative terminal. This reduces the risk of a spark near the battery
• Wait a minute or two if you’re not using a jump pack, and then attempt to start the mower
• Disconnect the leads in reverse order, removing the negative from the mower frame then donor, and then positive from donor then mower, to reduce the risk of shock

If the mower starts, but doesn’t hold charge after the next session, it’s likely time to replace the battery. Modern batteries last 3 to 5 years on average with reasonable care.

Tyre Pressures

This one is really easy to overlook, but it makes a real difference to the handling, performance, and fuel efficiency of your mower. It’s not uncommon for ride-on tyres to lose pressure slowly over winter, and even without a puncture, they can lose several PSI just from the cold and sitting static.

Incorrect tyre pressure causes uneven ground contact, which in turn leads to an uneven cut height across the width of the deck. On sloped ground, you’ll find that a mower with underinflated tyres struggles far more to grip onto the ground.

You’ll need a tyre pressure gauge and the means to inflate – whether this be a simple pencil gauge and foot pump, or an inexpensive air compressor (these often double up as gauges too!)

• Find the correct pressure. The manual is the best place to look, as each machine varies and there is usually a pressure difference between the front and rear tyres. As a rough guide, many ride-ons run front tyres at 10-14 PSI, and the rears at 8-12 PSI, but it’s always best to check what’s recommended by the manufacturer for your machine. You might also find pressure information printed on a sticker under the seat in some makes.
• Check when cold. Pressure readings are more accurate when the tyres haven’t been in recent use – not a problem if you’re just getting it out of the shed after winter, but worth noting that you might need to check again later if you need a mid-season pump-up.
• Remove the valve cap and connect the gauge. Press the gauge firmly onto the valve stem and note the reading.
• Inflate or deflate as needed. If the pressure is too low, use your pump to bring it up, keeping a close eye on the pressure. If you’re using a foot-pump without a gauge, pump in small amounts and then recheck with your gauge. If overinflated, you can let a little air out by pressing in the little pin in the center of the valve stem.
• Replace the valve caps. Don’t forget this bit, as the valve caps keep dirt and moisture out of the valve, and prevent accidental deflation.

Engine Oil Levels

Running an engine without enough oil is one of the single most damaging, and most avoidable, things you can do. Oil degrades over time and is slowly consumed over the course of a season, so if you haven’t opted to book in for our all-encompassing annual winter service (in which we replace the engine oil on your behalf), it’s worth checking the level before the first run of the year.

Most ride-on mowers use either an air-cooled single-cylinder or V-Twin petrol engine, which use standard 10W30/SAE30 engine oil. If in doubt, consult your user manual.

It only takes a minute or two to check your oil level and refill if necessary. Here’s the steps:

• Park on a level surface. The dipstick reading will be inaccurate if the machine is on a slope.
• Ensure the engine is cold (or has been off for at least 10 minutes). Hot oil expands and will give a false high reading.
• Locate the dipstick or oil filler cap. On most ride-ons this is on top of or to the side of the engine. Look for a bright yellow or orange handle, or a cap marked with an oil can symbol.
• Remove the dipstick, wipe it clean with a rag, reinsert it fully, then remove it again and read the level. The oil should sit between the “MIN” and “MAX” marks. Ideally it should be close to “MAX.”
• If topping up, use a funnel to avoid spills and add oil gradually, as small engine can go from low to overfull quickly. Recheck after each addition. Overfilling is also harmful as it can cause oil to be pushed into the air filter and combustion chamber.
• Check the oil condition. Fresh oil is amber-coloured; oil that’s past its best is dark brown or black and may smell acrid. If it looks like this, consider an oil change before the first mow of the season rather than simply topping up.

Coolant Levels

Most standard ride-ons use air-cooled engines and have no coolant system, and if that’s the case you can skip this stage. Higher-end lawn tractors, zero-turns and some professional-grade machines do use liquid-cooled engines, and in that case they need a coolant level check just the same as a car does.

If you’re unsure whether or not your ride-on is air-cooled or not, check your manual, or check for a radiator and coolant reservoir, which aren’t present on air-cooled engines.

Here’s how to check your coolant:

• Locate the coolant reservoir. It’s normally a translucent plastic tank, often mounted near the radiator. It will have MIN and MAX markings on the side.
• Check the level visually without opening the cap. The coolant should be between the two marks.
• If topping up, use a 50/50 premixed coolant or mix concentrated coolant with distilled water to the manufacturer’s specification. Do not use plain tap water as the minerals can cause internal corrosion.
• Check the coolant colour. Coolant that has degraded will appear brown and murky. If this is the case, it’s a job for our workshop rather than a simple top-up.
• Check for leaks. While the engine is cold, have a look underneath and around the hoses for signs of dried coolant (usually white or rust-coloured residue). Any active leaks should be investigated before running the machine.

Filters and Spark Plugs

Without clean air filters and well-performing spark plugs, your machine will run poorly and cut out regularly, if it starts at all. If you’ve had an annual winter service from a reputable dealer, this should have been taken care of for you.

Otherwise, pop out the air filter (usually in a plastic clip-on or spin-on case on the side of the engine) and check it for dirt, debris and residue. If it’s a foam filter you can wash it in warm, soapy water, dry it, and gently re-oil it before reinserting. Paper elements should always be replaced once they go gray or get clogged.

Next, take off the spark plug cap (or caps), and unscrew the plug with a wrench. Look at the electrode and make sure there’s no fouling or erosion. If you’re not sure, or if your plug has been in-situ for more than 100 hours or two seasons, it’s time to replace. Get a good-quality brand-name plug (we offer NGK plugs, just bring your existing plug in to us) and screw it in. Spark plugs are inexpensive, and you’re unlikely to ever pay more than £10 for one.

Cutting Deck & Blades

Keeping your cutting deck and blades in good condition mean you get the most out of your mower, as blunt blades put extra strain on your engine and leave the grass in a poor condition.

With the ignition key removed, tip the deck inspection plate or use a blade inspection stick to check the blades. After a winter, blades can be dull or have nicks from last season. Sharp blades cut cleanly; blunt blades tear the grass, leaving a brown, ragged finish.

While in the deck area, visually inspect the deck belt(s) for cracking, fraying, or glazing. A belt that goes mid-season usually means a frustrating delay.

Fuel

Fuel is the number one killer across all petrol garden machinery. Modern E5 and E10 fuel goes stale within 30-60 days from pumping, so it’s really important to drain your machine before winter storage, if you’re not using fuel stabiliser, or an Ethanol-free fuel designed for garden machinery like Aspen fuel.

If the mower has been stored with old fuel in it, the petrol may have degraded and left a varnish in the carburettor. This is a common cause of starting trouble. Drain old fuel and replace with fresh if in any doubt.

When to book a service instead

If you’re not confident working on the engine yourself, or if the mower shows any of these signs, it’s time to bring it in:

• Won’t start despite a charged battery and fresh fuel
• Running rough, smoking, or losing power
• Cutting deck vibrating excessively
• Oil that is very dark, milky, or low with no obvious reason
• Any fuel or coolant leaks

A pre-season service from a qualified technician will cover all the checks above and more, including carburettor cleaning, blade sharpening and balancing, belt inspection, and a full safety check. It’s the best way to ensure the mower is ready for a full season’s work.

Quick Reference

Now you know what to look out for, here’s a quick-reference table to check before that first mow:

Check	What to look for	Action if needed
Battery	Voltage, terminal corrosion	Trickle charge or replace
Tyres	Pressure vs. spec	Inflate/deflate to correct PSI
Engine oil	Level between MIN/MAX, colour	Top up or change
Coolant (if applicable)	Level between MIN/MAX, colour	Top up with correct mix
Air filter	Cleanliness	Clean or replace
Spark plug(s)	Electrode condition	Replace if worn or overdue
Blades	Sharpness, damage	Sharpen or replace
Drive belts	Cracking, fraying	Replace if worn
Fuel	Age and condition	Replace if older than 30 days

If you have any questions about your specific ride-on mower, or you’d like to book a pre-season service, get in touch with the team at Hertfordshire Garden Machinery. We stock a wide range of ride-on mowers, parts, and accessories, and our workshop handles everything from routine servicing to full engine repairs.