A cold or drizzly morning, you need to go, and the engine only clicks or turns over weakly. This happens most in winter, when damp settles on the ignition wiring and cold saps the battery.
No need to panic: the cause is usually simple and you can find it yourself. Work in order, from the simplest checks to the harder ones, and do not wear out the starter with long attempts.
What you will need
Important: Do not crank the starter for more than 10 seconds per attempt and pause 30-60 seconds between tries. Switch off the ignition before working under the bonnet, and never smoke or use naked flames near the battery.
Step 1
Check the fuel and the simple things
Look at the fuel gauge: if the car died while driving, it has most likely simply run out of petrol or diesel.
Put an automatic in P or N, or press the clutch on a manual.
Step 2
Assess the battery
Switch on the ignition and headlights. If the dashboard lights are dim and the starter clicks or stays silent, a flat battery is to blame.
Jump-start from another car or use a charger. Once running, fully recharge the battery, and if it is old, replace it with one of the correct specification.
Step 3
Clean the terminals and connectors
Corrosion on the terminals behaves like a flat battery even when the charge is fine. Remove the negative clamp first, then the positive, and brush off the deposits.
Spray WD-40 Specialist Contact Cleaner onto the terminals, clamps and earth connector and let it dry. It evaporates without leaving a film. Reconnect positive first, then negative, and tighten firmly.
Step 4
Dry out the ignition system
After rain, an engine wash or fog, moisture on a petrol engine's HT leads, coils and distributor cap (on older cars) lets the spark track to earth. If you see sparking on the leads while cranking, this is your culprit.
With the ignition off, spray the leads, plug caps and coils with WD-40 Multi-Use. It gets under the droplets and pushes the moisture out. For precise application into gaps, the two-position straw of WD-40 Smart Straw is handy. Then try again.
Step 5
Check the wiring and earth points
Look for an unplugged connector or a chafed earth strap. A loose or corroded earth often makes the starter turn weakly.
If the starter makes no sound at all with a charged battery, the fault may be in the starter itself, its relay or the ignition switch. Call an auto electrician.
Step 6
Know when to stop
Push-starting only works with a manual gearbox: ignition on, second gear, clutch down, then release smoothly once rolling. Never do this with an automatic, and avoid tow-starting a cold diesel.
If the starter spins briskly but the engine will not catch after a few tries, do not run the battery flat. The problem is probably fuel or air supply, and the car should go to a garage.
Tip: Keep a
pocket-size WD-40 100 ml in the glovebox: on an autumn morning after a damp night, a quick spray on the ignition leads and connectors often solves the problem without calling a tow truck.
What next
To make sure the engine starts first time, check the battery and clean the terminals before winter, and once a season treat the connectors under the bonnet with WD-40 Multi-Use to protect them from moisture and road salt. If the problem keeps coming back, have the car diagnosed rather than cranking it over and over.
These uses come from the experience of WD-40 users in many countries. Always follow the instructions and warnings on the product label.
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