Guide : when and how to replace your starter motor

MAINTENANCE

When and how to change
the starter motor on your machine

The starter motor spins the engine using power from the battery. Over time it wears out: here is how to spot a fault and replace the part safely.

QUICK ANSWER

	Symptoms: no cranking, slow cranking, clicking, a burning smell.
	First of all: machine off, battery disconnected, ventilated area.
	Replacement: remove the old starter motor, fit the new one with clean terminals and correct tightening.
	Checks: battery, clean connections, oil level.

HOW IT WORKS

1	Power supply The battery powers the starter motor's electric motor.
2	Drive The motor drives a pinion (or Bendix gear) that meshes with the ring gear.
3	Disengagement The petrol engine is cranked; once it runs on its own, the starter motor disengages.

PREVENTIVE MAINTENANCE

Clean connections

Clean the terminals and posts to prevent corrosion.

Suitable battery

Correct capacity and regular charging.

Oil level

Keep the level right to protect the engine.

Storage & cleaning

Keep dry, away from damp. Dust off the electrical components.

WHEN TO REPLACE

	The starter motor doesn't turn, or turns too slowly, despite a healthy battery.
	Visible damage: heavy corrosion, a cracked casing, a burnt smell.
	High age and use with repeated faults. Always check your model's manual.

REPLACEMENT STEPS

CAUTION

Always disconnect the battery before any work (negative terminal first). Switch off the ignition, let it cool, keep away from any flame or spark and wear gloves and goggles.

1	Make it safe Disconnect the battery. To prevent any start-up, also remove the spark plug if needed.
2	Access & disconnect Locate the starter motor, clear away covers and guards if needed, then remove the power cable and the control wire.
3	Remove Undo the fixings and take out the old starter motor.
4	Fit the new one Install the new starter motor, tighten to the recommended torque, then refit the cables with clean, dry terminals.
5	Put back into service Reconnect the battery (positive then negative) and test the start-up.

TOOLS YOU NEED

SPANNERS

Box spanner or socket wrench for the fixings.

SCREWDRIVER & RATCHET

Screwdriver and a small ratchet for access.

CLEANER & BRUSH

Contact cleaner and a brush in case of oxidation.

SEE OUR STARTER MOTORS →

TESTS & TROUBLESHOOTING

WHAT TO CHECK	WHAT TO DO
Battery	Well charged and in good condition; charge or test it before blaming the starter motor.
Connections	Clean, tight and insulated; if oxidised, clean and re-tighten.
Starter cable	Intact sheathing and continuity OK; replace the cable if it is damaged.
Noise / cranking	No unusual noise, the drive engages properly; otherwise, replace the motor or the drive.

FREQUENTLY ASKED QUESTIONS

The starter motor clicks but doesn't turn?

A weak battery, a poor contact or a starter motor at the end of its life. Charge and test the battery, clean the terminals before blaming the starter motor.

After replacement, it starts poorly?

Recheck the earth and the chassis, the tightness of the terminals, the condition of the spark plug and the oil level.

NEED THE RIGHT STARTER MOTOR?

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When and how to changethe starter motor on your machine

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When and how to change
the starter motor on your machine