Electrical blackout

[lomh 13]

Sorry for the delay, but I'm a little busy right now.

Following your advice I checked the ground connections.
On the engine side it seemed fine, but I took it apart and cleaned it.

In the trunk, I had already cleaned the battery connectors and also the grounding on the chassis three mouths ago and it is still clean.
.
But the engine still wouldn't start.
I then lifted the back of the car and found this.

The previous owner had installed a strap to support the exhaust and he had found nothing better than to place this strap between the bolt and the frame.

Many thanks to all the contributor of the forum.
I don't have been able to find the earth connections on the chassis except the batterie at the rear and the strap on the engine mount.
Next time I lift the car, I'll search for the other connections.

[nmauduit]

Bonsoir,

just in case: is the starter relay getting hot when you try to start the engine (i.e. how much current is flowing in the circuit)? if so there may be a short circuit in the starter circuit (result being all the current the battery can offer goes to heat while dropping the voltage into whatever resistance it finds along the way)...

In order to assess if the battery/starter part is ok, the use of a jumper cable in parallel of the battery loom may help : this is what I would try first after realizing that I get a general voltage drop upon cranking (I can even put a spare battery in parallel with the circuit directly on the dash mounted starter relay on my S4). Stay close to it at first, in case there is a short...

bonne chance !

[HCA]

Sorry for the delay, but I'm a little busy right now.

Following your advice I checked the ground connections.
On the engine side it seemed fine, but I took it apart and cleaned it.

In the trunk, I had already cleaned the battery connectors and also the grounding on the chassis three mouths ago and it is still clean.
.
But the engine still wouldn't start.
I then lifted the back of the car and found this.

The previous owner had installed a strap to support the exhaust and he had found nothing better than to place this strap between the bolt and the frame.

Many thanks to all the contributor of the forum.
I don't have been able to find the earth connections on the chassis except the batterie at the rear and the strap on the engine mount.
Next time I lift the car, I'll search for the other connections.

A big well done Robert in your perseverance to find the culprit!

I would never in a million Sundays thought of telling you to look at the exhaust hanger! You illustrate perfectly how difficult it is to analyse anything outside of the ordinary in a forum!

I am going to be a real bore and ask that you look at the engine strap again - if you have a Dremel, disc the chassis so that it is really shiny, same with the strap and re-install with a smear of Vaseline...

[elans3]

Alan, i just tested the almost new battery on the Elan, and that shows 12.6 volts and starts easily.
However, you must be onto something, as when I turn the ign switch to crank, the voltage drops to less than 2v.


HCA I have checked & rechecked all the contacts that I cleaned this morning (they weren't really dirty anyway, & not corroded at all. Engine earth perfect, gearbox earths perfectly, chassis earth perfect.

Just to explain, it went from cranking well, (I didn't catch it on the throttle), then zero.

I checked some more:- Headlights don't work, indicators don't work, heater fan doesn't work, sidelights work dimly, wipers work slowly. No ign (or gen light) All fuses are good, and fuse terminals test out at both contacts.

Could it be a short somewhere ? No smoke anywhere when ign is turned on , or turned to crank.


I apologise to LOMH13 for hijacking this thread, but as our issues are very similar, it may throw something up that helps both of us.

[HCA]

If the battery starts another car and it is 12.65V, it is fine.

By going down to 2V when you switch ignition on empasises that the power from the battery is not making a complete circuit. There is a blockage somewhere.

If there were a short circuit, you would know about it...

The fact that your other devices do not work highlights the poor connection somewhere.

As I said, it is very difficult to diagnose remotely. But, like the OP, you have a blockage somewhere. I just cannot suggest where you look outside of the obvious

[alanr]

Ok..Down to 2volts is not good!
I don't suppose you have a 'High rate discharge tester' to drop across the battery?...I know you say it starts another car but it could still have a duff cell boiling under load.
Even though you have 12.65v surface charge something is obviously dropping the voltage when you turn the start key.
I assume the car is negative earth.
What happens if you do the same voltage test, turning the ignition key to start with the voltmeter + side clip on the solenoid large input terminal and the -negative earth clip on the voltmeter on the battery earth terminal.
Do you still get the same volt drop?
I'm not that familar with the Alfa layout so unsure of the distance involved between terminals with doing the above test.

[alan.barker]

bonjour lomh 13,
il faut devisser et demonter le Vis pour le Masse dans le Coffre. Poncer le Bride du Chassis, passer un Tauraude dans le filetage du Bobbin. Remonter avec Vis, Ecrou, Rondelle neufs.
Bon chance
Alan

[alanr]

Please keep the thread in English when the thread is being discussed in English and then we can all share!!

Alan

[alan.barker]

Please keep the thread in English when the thread is being discussed in English and then we can all share!!

Alan

Hi Alan,
Lombh 13 lives in the south of France so i thought if he's French and has problems with English i am ready to help him. After living in France for 30 Years it's become natural to jump from one Language to another and i forget about others that can't
Alan

[alanr]

Hi Alan,
No harm done!
I think Lombh13 is now sorted and has found his problem anyway.

The thread has now moved on to a similar problem with elan3's Alfa!...and I have soft spot for Alfas even though they do rust away before your very eyes. Also a 2000GTV many years ago nearly killed me when I rolled one down a twisty country lane when being too heavy right footed!!

Regards,

Alan.

[Bud English]

The picture of your clean ground terminals might explain your problem. That is not the usual place for the chassis earth point. The aluminum body mount bobbins might be a good grounding point if the head end of the bolt where it actually goes through the chassis is as squeaky clean as the end that you can see. That bolt coming through from the under side of the car is even more exposed to the elements than the normal ground point.

You might have a look at this thread. It shows a mod to the ground point but does show where the ground terminal is normally mounted.

Duh, here's the link. viewtopic.php?t=45064&p=321352

[elans3]

Ok..Down to 2volts is not good!
I don't suppose you have a 'High rate discharge tester' to drop across the battery?...I know you say it starts another car but it could still have a duff cell boiling under load.
Even though you have 12.65v surface charge something is obviously dropping the voltage when you turn the start key.
I assume the car is negative earth.
What happens if you do the same voltage test, turning the ignition key to start with the voltmeter + side clip on the solenoid large input terminal and the -negative earth clip on the voltmeter on the battery earth terminal.
Do you still get the same volt drop?
I'm not that familar with the Alfa layout so unsure of the distance involved between terminals with doing the above test.

Hi alanr,
Once again, thanks for your input. Yes I've just tested from the neg battery terminal to the big input terminal on the solenoid. Same voltage drop. I'm beginning to suspect the battery. HCA, above, misunderstood when I said I'd tested the battery on the elan and got a similar reading to the Alfa, seeing 12.6-ish volts from each. He thought I'd tested the Alfa battery on the Elan. (I hadn't), I assumed that seeing 12.6V on both batteries that the Alfa one must be ok. Its also an Exide, top quality, and has a "tell tale" green light on the top showing that everything should be ok.
I then "bench tested" an old spare Alfa starter on the Elan, and it operated perfectly. Went to do the same on the Alfa battery (still connected to the car), and nothing but a weak spark from the casing when I earthed it to the battery neg terminal.
In 50 years of messing about with cars, I've never, ever seen a battery go down instantly like it (potentially) has.
And showing 12.65 V until you try to crank it, is a new one for me also, however, electrics is my downfall, so not surprising that it's taking time to find.....
Tomorrow I will take the battery off the Elan and try it on the Alfa. Hopefully that's the answer.
Will report back tomorrow pm.
Many thanks again chaps.

[69S4]

In 50 years of messing about with cars, I've never, ever seen a battery go down instantly like it (potentially) has.
And showing 12.65 V until you try to crank it, is a new one for me also, however, electrics is my downfall, so not surprising that it's taking time to find.....

I've had it happen on a (large) motorcycle. It started perfectly on my drive, I rode 1 mile to a fuel station with the voltmeter showing normal and it was completely dead after refuelling. It seems that the AGM style batteries are more prone to this, although quite why I'm not sure. I checked all the other possibilities like earths etc back at home but it was battery sudden death. A new one was the obvious fix.

[alanr]

elans3
It strongly looks like you have a duff battery with a faulty or dead cell. Just a surface voltage measurement alone means very little really. It is what the battery performs like under load that is important.
Please keep us posted with the outcome.

Alan.

[lomh 13]

As I said, my problem was that the head of the bolt underside of the car was not in contact with the chassis because of a rubber strap fitted bu the previous owner to hang the exhaust.
I have Also an Alfa (1974 GTV 2000) and experienced som trouble with the starter motor. But for me it was the oposite. No voltage drops, but starter turned very slowy. It was the starter motor that was faulty.
I confirm, on the Alfa there is a positive lead witch ru from the batery to starter motor a more smaller that goes betwen the starter motor to the ignition key ans fuse box.
For the negative lead, one from the battery to the engine and one from the engine to the body.
With a voltmeter you can check were is the problem.
If it was me, using one lead of the voltmeter on the négative socket of the battery and the other on the chassis, your reading should be zero. When you turn on the ignition key it would remain to zero. If it is not the case, ther is a problem with the negative circuit. You can check the positive the same way.