The Primera won't start . The starter turns, but obviously isn't engaging as you can hear it spin much faster than usual. It's been sounding a bit rough for a while, but gave up completely on Sunday. I had to get the AA out, and we bump started it after which it was fine, so I'm pretty sure there's no other problem.

I can get a new replacement starter for about

 

Does it make a clicking noise when you turn the key, and the engine doesn't turn over?

 

He's referring to the ring gear which runs around the edge of the flywheel.

If that's buggered then it probably means a new flywheel.

It could be the pinion on the end of the starter that's buggered or the pre-engagement mechanism. Personally i'd go for the new starter.

 

You're thinking of a sticky solenoid. If the starter is turning it won't be that.

 

Ta. Yes I guess it makes sense to go for the new starter, assuming I can work out where it is and change it. The Haynes manual is a bit crap.

Is the solenoid what pushes the gear into place? Surely the motor would still turn if the solenoid is sticking?

 

The solenoid provides the power to the starter motor itself. If the solenoid sticks the starter won't pre-engage or turn the starter motor.

 

Yes I thought the solenoid did act as a relay, but does it also engage the gear? That's what wikipedia suggests.

Does the fact that the motor is turning suggest that the solenoid must be working okay and it's likely the flywheel ring that's knackered, or is it possible that a knackered solenoid would supply power but not engage the gear?

 

Yes, the solenoid also provides the power to pre-engage the pinion on the starter motor before the starter motor starts to turn.

If the starter motor is turning the solenoid is obviously fine. The problem must lie with the starter motor pre-engagement mechanism, the starter motor drive pinion or the flywheel ring gear.

I think the most likely culprits will be the starter motor drive pinion or the pre-engagement mechanism. If the drive pinion teeth are worn out then the starter motor will just spin without turning the flywheel or if the pre-engagement mechanism hasn't worked then again the starter motor will just spin.

I'd be surprised if you've lost all the teeth on the flywheel ring gear but its possible you've lost a few and the flywheel just happens to have stopped at the wrong point. You could try turning the engine over by moving the car in gear to move the contact point on the ring gear, but my money's on the drive pinion particularly as you'd commented it had been making a bit of noise for a while. Its probably been shedding teeth over time.

 

hit the starter with a hammer then try it

 

I have actually driven it since the problem (bump started) and checked that it wouldn't start again, so unless it happened to end up at the same point on the flywheel that suggests it must be the motor.

Thanks Rich.