Brush cutter winter storage: the 8-step end-of-season routine

Put a brush cutter away wet, dirty, and full of last month’s fuel, and you’re signing up for a carburettor strip-down or a seized gearbox come spring. None of the steps below take long, and together they’re the difference between a machine that starts on the second pull in March and one that needs a workshop visit first.

Step 1: Deal with the fuel first

Fuel is the single biggest cause of spring no-starts, and it’s worth doing properly rather than tipping the tank and calling it done.

1. If storage will run a month or longer (typical for a full winter), drain the tank fully — siphon or pour it into an approved container, never by mouth-suction.
2. With the tank empty and the cap back on, start the engine and let it idle until it stumbles and stalls on its own. That confirms the carburettor bowl or diaphragm chamber has run dry too, not just the tank.
3. If a full drain genuinely isn’t practical, add a fuel stabiliser at the dose on the bottle, run the engine for a minute so treated fuel reaches the carburettor, and keep the tank close to full to minimise air and condensation inside it.

Safety note. Drain fuel outdoors or somewhere well ventilated, away from any ignition source. Old fuel is hazardous waste — take it to a household waste recycling centre, never down a drain or onto soil.

Full step-by-step detail on siphoning, running the carb dry, and legal disposal is covered in our separate guide on draining old fuel; this routine only needs the short version above.

Step 2: Clean the cooling fins and cylinder head

Dust, chopped grass and dried sap cake onto the cylinder fins and around the muffler over a season, and that layer is exactly what traps moisture against bare metal all winter.

1. Remove the cylinder cover / shroud (usually two or three screws) to expose the fins properly — don’t just wipe around the outside.
2. Use a stiff paintbrush or a length of wood/plastic (not a metal scraper, which can nick soft alloy fins) to clear compacted debris out from between the fins.
3. Blow it out with compressed air if you have it, working from the inside out so debris doesn’t pack further in.
4. Check the spark arrestor screen in the muffler at the same time — a clogged one is a common cause of poor cold-start performance in spring, and cleaning it takes two minutes with the cover already off.

Safety note. Let the engine cool fully before touching the muffler or fins — even after an hour, muffler bodies can still be hot enough to burn skin.

Step 3: Fog the cylinder (2-stroke and 4-stroke engines)

Fogging leaves a protective oil film on the cylinder wall and rings, which matters most for storage of four months or more, or in a damp/unheated shed.

1. With the spark plug removed and the machine on a level surface, spray a short burst of fogging oil (or, failing that, ordinary 2-stroke oil from an oil can) directly into the spark plug hole.
2. Pull the starter cord slowly two or three times with the ignition off, to spread the oil around the cylinder wall and rings without firing the engine.
3. Refit the spark plug but leave the ignition lead off it until spring, as a visual reminder the machine has been put away — a genuinely disconnected lead also means nobody can accidentally start it while it’s on the bench.

This step is optional for short gaps of a few weeks, but worthwhile for a full winter lay-up — it costs two minutes and one squirt of oil.

Step 4: Batteries — the step people get wrong

Cordless brush cutters are the one area where “fully charged and ready to go” is the wrong approach for storage.

Storage practice	Effect on Li-ion battery
Store at 100% charge for months	Accelerates capacity loss; cells held at full charge degrade faster
Store fully flat (0%)	Risk of the pack dropping into deep discharge, which can permanently damage cells
Store at ~40-60% charge	Best long-term storage state; minimal degradation over winter
Left in the machine, in an unheated shed	Fine short-term, but repeated freeze/heat cycling shortens pack life over years

1. Remove the battery from the machine entirely — don’t leave it clipped in over winter.
2. Charge or discharge it to roughly 40-60%, not a full charge.
3. Store it indoors somewhere cool and dry — a cupboard or utility room is better than an unheated shed or garage that sees hard frosts or summer-hot roof spaces.
4. Check it again around the two-to-three-month mark; if it’s drifted down near empty on its own (self-discharge), top it back up to that 40-60% band rather than leaving it fully flat.

Safety note. Never store a swollen, damaged, or physically dented battery pack indoors — isolate it outdoors away from combustibles and follow the manufacturer’s advice on disposal or return.

Step 5: Grease the gearbox

The angle gearbox at the head end takes a season of heat and vibration and is easy to forget because it’s out of sight.

1. Locate the grease fill/level plug on the gearbox housing (usually a single screw on the side or top).
2. Remove the plug and check the grease — it should still look like grease, not a thin, dark, burnt-smelling residue.
3. Top it up with the gearbox grease specified for your model if the level looks low; most small gearboxes only need a small amount, so don’t overfill to the point it has nowhere to expand.
4. Refit the plug and wipe off any excess from the housing exterior.

Doing this before storage rather than in spring means any grease that’s degraded over the season isn’t sitting in there drying out further over winter.

Step 6: Give the shaft, head and blade a proper clean

1. Wipe down the drive shaft tube and remove any wound-in grass or string from around the gearbox and guard.
2. If fitted with a trimmer head, remove old line if it’s more than a season old — nylon line degrades and gets brittle sitting in a damp head over winter — and either leave it empty or fit fresh line before storage.
3. If fitted with a metal blade, remove it, clean off sap and debris, and wipe it with a light coating of oil to stop surface rust forming over winter. Store it somewhere it can’t fall on anyone or get walked into.
4. Wipe the whole machine down with a dry cloth, including the harness or handle grips, so nothing is left damp against the housing.

Step 7: Store it dry, upright, and off the floor

Where a brush cutter sits matters as much as how you prepped it.

• Keep it off a concrete or bare floor — cold concrete draws moisture and encourages surface rust on the shaft and fasteners; a couple of wooden battens or a shelf is enough to break contact.
• Store it somewhere dry rather than a damp lean-to or open-sided shed; a garage, insulated shed, or indoor store cupboard is preferable.
• Hang it or lean it so the guard and head aren’t taking the machine’s weight, and the blade (if fitted with one and stored on the machine) isn’t resting against anything it can mark or be marked by.
• Keep it away from where it can be knocked or where children or pets have unsupervised access, even switched off and with fuel drained.
• Loosen the throttle trigger and choke linkage by leaving them in their natural rest position rather than storing under tension for months, if your model allows this.

Step 8: Spring wake-up checklist

When it comes back out, don’t just splash in fuel and pull the cord. Work through this before the first cut of the season:

• Reconnect the spark plug lead (removed in Step 3) and check the plug gap is still around 0.5 mm; replace it if it’s fouled or the electrode is worn.
• Fill with fresh fuel — properly mixed 2-stroke fuel at the ratio specified for your engine, not whatever was left in a can over winter.
• Refit a charged battery (cordless models) and check it takes charge normally before heading out to use it.
• Check the air filter is clean and seated properly; a filter left in over winter can pick up condensation.
• Inspect the line or blade, the guard, and all visible fasteners for anything that’s loosened or corroded.
• Start it in open air, away from anyone else, and let it idle for a minute before loading it up — this is the point where a partially blocked jet or a fouled plug from imperfect winterising will show itself.

Safety note. Always do the first start of the season outdoors, at least 15 m from other people, with the cutting attachment fitted correctly and the guard in place — don’t test-run it “just for a second” indoors or in a garage.

When to call a dealer

Most of the above is well within reach of anyone comfortable with basic hand tools. Call a dealer or small-engine mechanic instead if, at spring wake-up, you find: fuel that’s turned to visible varnish inside the carburettor bowl despite draining, a gearbox that feels gritty or won’t turn freely after greasing, a battery pack that’s swollen or won’t take charge at all, or a pull cord that’s seized solid over winter. Those point to a problem beyond routine storage prep, and forcing it usually turns a small job into a bigger one.

Quick checklist

• Fuel drained (or stabilised for short gaps) and carb run dry
• Cooling fins, cylinder head and spark arrestor cleaned
• Cylinder fogged with oil for storage of four months or more
• Battery removed, charged to 40-60%, stored indoors and cool
• Gearbox grease checked and topped up
• Shaft, head and blade cleaned, blade lightly oiled
• Machine stored dry, off the floor, away from foot traffic
• Spring checklist run through before the first real cut