Morris Minor Owners Club

Hi All
Just thought I'd recount my recent issue.

Car had been starting perfectly, one pull on the Start Switch Knob and she was firing yo.
Then the next time I went to move the car.....
Key on...
Green/Red lamps on Speedo light up...
Pull the Start and no starter sound, Green/Red Lamps go out
Lamps don't come back on until Key Switch cycled (that bit still puzzles me)...

Go under the bonnet, try the centre button on Start switch, nothing...
Short out terminal posts on Start Switch, Nothing...
Think it must be the starter, perhaps a short in the windings pulling the voltage down.
So whip that off, but it turns out that it spins easily on the old spare battery using Jump Cables...
Decide it must be to do with the Start Switch, so ordered one anyway....
Wary of putting what appears to be a short on the battery and damaging it, but can't fathom out how/why...
Tried it one more time, with the garage very quiet, and could hear a slight arcing noise, like spark jumping...
But I have already checked the Starter.
I take a close look at the Battery cable from Battery Post to Start Sw. Flex it a little.....
All became clear....

In the normal scheme of things, the Starter Switch and the Starter Motor are probably <1 Ohm resistance each.
The full power of the battery gets to the motor windings and it's off spinning it's merry way around.
This cable has been progressively breaking strands and every time I started the car a few melted or arced.
It got to the point where this connection had enough resistance it was pulling a few amps and the power of the battery was going into this, acting like a little heater, with nothing powering the starter.
It's a good job I never gave it more than 1-2 seconds of Starter Switch each time.

So the moral of this tale is don't discount cable deterioration, just because it's as thick as a Starter cable...
As a temporary measure, I've shortened the cable and re-terminated, just to prove it is fixed, but will sort out both battery connections in the near future.... At least I'll now have a spare Start Switch in the spares box....

Well found! I have had similar problems with the positive cable on my every day Astra and last week on the wife's MINI Cooper - couldn't make it up!

Alan

Looks like a cheap steel welding earth strap. A cheap substitute for a proper copper conductor.

oliver90owner wrote: ↑Tue Jul 19, 2022 9:05 pm Looks like a cheap steel welding earth strap. A cheap substitute for a proper copper conductor.

I suspect it's the original 1955 wiring.
Copper was in short supply post WWII so steel and other alternative metal wiring was far more common in vehicles, including aircraft.
Aluminium wiring is still used in aircraft where the calculations make it viable. There are complex Pros and Cons of its characteristics to account for.
The Copper shortage post war is considered the principle reasons the UK has Ring Main wiring, whereas most of the world still uses multiple spurs from their distribution units.
Traditional wiring had a separate line going out to each socket or light fitting.
Putting a ring in the property probably halved the amount of wiring used.

Just to draw this to a conclusion....
I ordered a 24" 16mm2 insulated Copper earth cable with an 8mm hole tag on each end. Only £7 on ebay. Cut it in half and terminated the new ends with the battery post clamps.
That cable size is rated at 110Amp and I know the Minor draws only about 85-90 Amp when turning the engine over, so it's well within respectable limits.

oliver90owner wrote: ↑Tue Jul 19, 2022 9:05 pm Looks like a cheap steel welding earth strap. A cheap substitute for a proper copper conductor.

Before I binned the old cables, I examined the strands and they were actually a coated copper, zinc perhaps, as a scrape with a knife blade cleared the coating off and showed a nice copper inner to the strands.