Page 1 of 1

Starter shorting/cooking wires

Posted: Sun Jul 06, 2025 12:40 pm
by leeandoona
So. My minor which has sat idle for many many many months wouldn’t start or even turn. It’s a 58 and has a pull starter. When pulling the starter knob the dash lights dim. I checked the power to the starter motor and sure enough there was no power reaching it. I bridged the connection on the switch but this did nothing and did a volt meter test and no power was jumping from one side to the other unless bridged. I tested the starter independently and discovered it too was not working so removed it, bench tested and sure enough it was dead.
During all this I noted the wires were getting very hot when attempting to start/power the starter.
So I checked and cleaned all the earths, including the gearbox earth strap. Bought a new starter which I bench tested and confirmed was operating. Fitted the starter, pulled the starter knob and the starter span once and then after an audiable bang, it stopped working and returned to hot wires and dimming cabin lihjts.
Checked fuses, checked earths again. All lights operate as expected so appears to be electrically okay on that side of things. Removed new starter to discover it too is now dead. So it’s cooking starter motors. I’m assuming this is a short?
I’ve bought a new starter switch/solenoid (I know it’s not really a solenoid).
Anyone had this happen? I don’t really want to fit another starter and Jill that too!

Re: Starter shorting/cooking wires

Posted: Sun Jul 06, 2025 2:26 pm
by oliver90owner
First thing - can you confirm that the engine actually turns?

Further response after that.

Re: Starter shorting/cooking wires

Posted: Sun Jul 06, 2025 2:28 pm
by StillGotMy1stCar
Is the engine seized overloading the stalled starter motor. Can you turn the engine with the starting handle, fan or rocking in gear.

Regards John

Re: Starter shorting/cooking wires

Posted: Sun Jul 06, 2025 4:26 pm
by leeandoona
Engine turns freely. Yes. Not seized and I e turned it over using the starting handle.

Re: Starter shorting/cooking wires

Posted: Sun Jul 06, 2025 10:55 pm
by oliver90owner
Was the replacement starter motor a secondhand purchase or bought from a reputable source of refurbished starter motors.?

If the latter, I would think they should replace the unit. I cannot understand how the starter should fail so quickly. The loud bang would indicate something is shorting inside the starter motor. I’m assuming, here, that you did not engage the power for too long.

Re: Starter shorting/cooking wires

Posted: Sun Jul 06, 2025 11:54 pm
by leeandoona
Brand new from reputable minor specialist. No, it was literally one pull on the starter and a brief spin over of the engine, then bang and failure.

Wires from starter and to battery very hot. Can’t see any obvious signs of bad earth, all earth points nice and
Clean and when checked for continuity they show appear normal.

I’m assuming there is a short somewhere?

Re: Starter shorting/cooking wires

Posted: Mon Jul 07, 2025 4:57 am
by oliver90owner
Yes, there is definitely a short circuit somewhere. The starter motor windings should show a very low resistance, so not easily checked for true answer with a cheap multimeter. It would draw upwards of 200A at zero speed, so resistance of around 0.05 Ohms, and 60-70A when up to speed (impedance, rather than resistance while running).

Talk to your supplier is my advice.

As a further check is there a short circuit when operating the starter switch while the starter motor is disconnected? That should then be an open circuit (so no light dimming, etc).