- Most of a yearly mower service is about an hour of cheap checks on oil, air filter, spark plug, blade, deck and fuel, done with a socket set, a scraper and a funnel.
- A specialist earns the fee on the faults you cannot see or fix, so keep them for engine and drive trouble.
- Read the warranty paperwork before you pick up a spanner, and keep a note of what you did and when.
The shop quote is real money, so what are you actually paying for?
A typical petrol mower service in a repair shop costs around 70 to 180 GBP (roughly 90 to 235 USD), with an average near 150 GBP (about 195 USD). Parts are 20 to 60 GBP of that and labour the rest. For that you get a person working through a short list of parts. The list is the same one you can work through yourself.
A garden machinery specialist services and repairs mowers, petrol models above all, and a full service covers spark plugs, air filters, blades and oil. Nothing on that list is exotic. Each item is a wear part with a known job and a known way of failing.
The chore is worth doing. A survey of 5,387 mower owners by Which? found that more than one mower in ten did not make it past seven years without a fault. The same writers say a mower with proper maintenance and care should last at least a decade.
What a service really covers, and why each part wears
**Oil.** The more the engine runs, the more dirt and moisture get into the oil, and that mix corrodes the inside of the engine. Change it at the start of each mowing season or after 50 hours of use, whichever comes first, and check the manual for the grade your engine wants. The dipstick tells you the level, as it does on a car. Step by step instructions are in our guide to the pre-winter oil change.
**Air filter.** An engine burns fuel mixed with air, and the filter stops dirt, debris and grass from reaching the cylinder. As it clogs, the engine breathes through a blocked straw and runs worse. It sits on the side of the engine, attached to the carburettor, and one or two screws usually release it. Clean it at every check and replace it every year. A filter caked with dirt gets replaced, and a new one is cheap and easy to find.
**Spark plug.** The plug ignites the fuel and air mixture, so a dirty or failing plug means a mower that will not start or runs rough. A healthy plug from a well running engine is light grey or tan. Soot, oily deposits or baked-on carbon mean the plug is failing. Clean it or replace it. Which? advises replacing it annually, while Family Handyman replaces any plug that is over three years old with a new one of the same type, so yearly is the safe choice if you want no argument. Match the plug to the number in your manual. One common small engine plug, the Champion RJ19LM, sells for around 4 GBP (3 to 5 USD), a small sum set against a shop fee.
**Blade.** A sharp blade cuts the grass cleanly. A dull one rips at it, leaving torn tips that turn white, then yellow, then brown after the cut, and the damage can leave the lawn open to disease. Sharpen at least once every mowing season and check again halfway through. Signs of a dull blade are torn grass, uneven height, longer mowing time and visible nicks. A bent or badly chipped blade gets replaced, not sharpened. If you mow under trees, hitting exposed roots can dull or bend a blade quickly. Our blade sharpening and balancing walk-through covers the job in detail.
**Drive belt.** Self-propelled mowers use a belt to carry power from the engine to the wheels. Like the fan belt on a car, it dries out and stretches, and the drive weakens. Replacing it is quick, easy and inexpensive.
The jobs you can do in an hour
Family Handyman puts the spring tune-up at less than an hour and splits the work by season: fuel, spark plug, deck and fogging oil before storage, then blade, belt, oil and filter in spring. Do it all now if you prefer; the order below works either way. You need a socket set and ratchet, a spark plug socket, a funnel, an oil drain pan, a scraper and a few drops of machine oil.
**Pull the spark plug wire first.** Always. With the lead off the plug, the engine cannot fire while your hand is near the blade or you are tipping the machine. Reconnect it only once the blade is secured.
**Then work in this order:**
1. Drain and replace the oil. Tip the mower with the air filter and carburettor facing up, so oil and fuel do not run into the carburettor. Toro’s owner manual also says to let the fuel tank run dry before tipping, or to remove the fuel with a hand pump, so empty the tank first. Catch the old oil in a pan and take it to a recycling point.
2. Check the spark plug. Pull the cable gently, remove the plug with the socket, read the tip against the grey or tan test, and clean or replace it.
3. Clean or replace the air filter.
4. Remove the blade centre bolt with a socket and ratchet, using a block of wood to stop the blade turning. Inspect it, then sharpen or replace it. If you sharpen with an angle grinder, wear eye protection, earplugs and gloves, and follow the blade’s natural angle slowly so you do not change its shape. A repair or hardware shop will sharpen a blade if you would rather hand that one job over.
5. Look at the drive belt on a self-propelled mower.
6. Put a few drops of machine oil on each wheel axle and each control pivot point.
**Clean the deck.** Every cut leaves grass and debris under the deck, and it hardens into a crust that spoils the cut and, left alone, can spread lawn disease. Scrape down to bare metal with a small pry bar or a stout scraper. If the crust is dry and hard, soak it with a hose, wait an hour, then scrape. Ideally, clean the deck after every session, especially after cutting wet grass, and at the very least once a month. A wire brush, damp cloth or air line does the monthly job. Keep the hose off an electric mower: water in the electronic components damages them. The caked deck guide shows how.
Fuel and storage: the part most owners get wrong
Petrol goes off. A car uses its fuel quickly and modern fuel injection compensates for changes in quality. A mower engine is simpler, and most of us do not cut grass over winter, so the same tank sits for months. The fuel degrades into deposits and varnish that coat the inside of the engine and the carburettor.
Ethanol makes it worse. Ethanol is hygroscopic, which means it absorbs moisture from the air. Over time, that moisture condenses as water in the fuel tank. The mower then pulls the water through its fuel system, parts deteriorate and the engine can gum up. Any regular unleaded works, but a higher quality petrol with a lower ethanol content can be worth buying for a mower.
You have two ways to protect the engine, and owners split between them:
- **Fuel stabiliser.** This chemical slows the degradation of the fuel, so the petrol keeps its freshness and does not corrode the engine or leave gunky deposits behind.
- **Run it dry.** At the end of the season, run the mower until every drop of fuel is used. Fresh fuel goes in come spring and the engine stays clean. Siphoning out the remaining petrol is the alternative. Fuel left over winter degrades and deposits sink to the bottom, and the mower has a tough time starting.
Petrol that sat in a can over winter belongs in your car’s tank at your next fill-up, not in the mower.
For long storage, add fogging oil. Spray it into the air intake of a running engine and it coats the piston, cylinder and valves, the best way to stop internal corrosion over the off-season. It counts most where winters are cool and damp, the conditions that form condensation inside the engine.
A cordless mower needs less. Keep the battery indoors, away from hot sheds, charge it a few times over the off-season and never leave it sitting at 0 percent charge. A corded mower with a damaged cable stays unused until the cable is replaced or repaired as the manual’s safety instructions say.
What a shop does that you should leave to a shop
Do everything above yourself and you have done what a basic service sells. The shop earns its fee when the engine or drive fails a check you cannot fix at the bench.
- **The mower will not start after fresh oil, a good plug, a clean filter and fresh fuel.** Do not throw it out. A garden machinery specialist can repair a mower that looks broken, so ask before you scrap it.
- **The blade is dull and you do not trust yourself with a grinder.** A repair or hardware shop will sharpen it. A bent or badly chipped blade needs replacing.
- **A cordless mower has a dead battery.** A replacement can get the mower running again, though the price can surprise you, so check it before you pay for a repair.
The warranty comes first. Read the paperwork before you open anything on a mower that is still covered, and ask the seller what service record the cover wants.
How to stop big repair bills coming back
Small, regular habits beat one large bill. Clean the deck every month. Sharpen the blade once a season and check it halfway through. Keep a card in the shed with the hours you have mowed, so the oil change arrives on time instead of whenever you remember. Replace the spark plug and air filter every year, and the oil at the start of each mowing season or after 50 hours, whichever comes first. Before every cut, walk the lawn and pick up stones and sticks, which can dull a sharp blade or damage it badly, and can fly up and hurt someone.
Do that, and a shop visit becomes a job you choose to pay for when the engine or drive fails.
