A lawn mower works in tough conditions: wet grass, dew, soil and fertiliser stick under the deck, and then the machine sits in a shed for months. In spring the blade bolt will not budge, the wheels barely turn and the height adjuster jams.
Here is a sequence that frees seized parts without rounding off bolt heads, removes rust from the deck and keeps everything easy to undo next season.
What you will need
Important: Before any work under the deck, pull off the spark plug cap (remove the battery on a cordless model). Tilt a petrol mower with the spark plug facing up so fuel and oil do not flood the carburettor and air filter.
Step 1
Inspect and clean the deck
Lay the mower on its side and scrape dried grass from under the deck with a plastic scraper. Underneath you will see the real condition of the metal: surface rust, blistered paint or holes.
Wash the deck with warm soapy water and let it dry. Wet metal is hard to clean back and rusts again quickly.
Step 2
Free the seized bolts
Soak the blade bolt, wheel bolts and height adjuster with WD-40 Specialist Penetrant. It works into the thread and dissolves rust between the turns. Wait 10-15 minutes and repeat on very old joints.
Wedge the blade with a wooden block and turn with steady force, no jerking. If the bolt will not move, tap the spanner lightly with a hammer and apply the penetrant again.
Step 3
Remove the top layer of rust
Go over rusty areas of the deck and frame with a grinder or brush attachment. Then use a hand wire brush on corners, ribs and pits the tool cannot reach. Wear glasses and gloves, as rust flakes fly.
Step 4
Sand off what remains
Sand any remaining orange spots back to bare metal with medium-grit paper and wipe off the dust with a dry rag. Holes right through the deck need welding or a new deck, no lubricant will save them.
Step 5
Treat and protect the metal
Apply WD-40 Multi-Use to the cleaned areas and to levers, linkages, springs and the control cable. It displaces moisture, lifts remaining dirt and leaves a thin protective film. Wipe off the excess after a few minutes.
A thin film under the deck also helps wet grass stick less. The WD-40 Smart Straw reaches tight spots in the height mechanism.
Step 6
Grease the axles and reassemble
Before refitting the wheels, apply WD-40 Specialist White Lithium Grease to the axles and bushes. This thick grease is not washed off by dew or watering. Refit the blade, tighten the bolt firmly and reconnect the spark plug cap.
Tip: After mowing in wet weather, let the deck dry and give it a light spray of WD-40. In autumn, before the mower goes into an unheated shed, repeat the full treatment: Ukrainian winters bring condensation, and unprotected metal is rusty again by April.
What next
A monthly check of the bolts and deck during the season and proper storage in autumn will keep your mower going for years. The same products work for a trimmer, secateurs and a garden wheelbarrow.
These uses come from the experience of WD-40 users in many countries. Always follow the instructions and warnings on the product label.
More guides in «How to use».