I have recently found what I consider to be a reliability weakness in the 123GT wiring harness design, common to all vehicles of this model, which can possibly allow an inadvertent disconnection of the Battery from the Alternator output, resulting in damage. For details and a simple recommended improvement to eliminate the weakness, see: http://www.sw-em.com/123GT_Reliability_Weakness_and_Simple_Improvement.htm

I added a second fuse block to my 122S to handle power to headlights, horn, and driving lights, all of which are connected to relays. I was concerned about exactly the issues you present here - the numerous points at which the entire alternator output passes through some relatively small components - so I opted for a different approach. Since I wasn't trying to preserve the historic character of a 123GT, I situated the second fuse block on the driver's side of the engine compartment and tied it to the stud on the starter. That way the alt-to-batt connection is maintained through a single 8ga wire (from alt to starter) and the batt cable (from starter to batt).

I'm puzzled as to why Volvo didn't do it this way in the first place. Is there something inherently unwise about using the starter stud as a tie point?
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The other Phil S. | '68 Amazon daily driver

Hence, the sticker applied under the hood...

Question for you, Ron.. would you know if a Motorola in a '67 GT would be the same as that which would be found in a '68 140? Assuming it's a Motorola?
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-Matt I ♥ my ♂

Matt;

Likely the same alt...but you could check numbers on published parts to confirm.

What "sticker applied under the hood" do you mean?

Cheers

I guess checking numbers is probably best. Thanks. Not that I care much. I expect I'll eventually do the Delco..

As for the warning sticker, it is here: http://i.imgur.com/dQkmn9d.jpg
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-Matt I ♥ my ♂

Matt;

This is even more important and highly recommended when changing over to a Delco, as it can nominally put out double the current resulting in basically double the transients!

Thanks for picture of sticker...it shows Volvo recognized the importance of not disconnecting the Alt output, and felt it important enough to add a warning sticker...again, the original design and construction is fine, but 50 years later, as looseness or poor connections due to corrosion develop (as we know they can), the possibility of disconnection becomes greater, so needs to be checked for and prevented.

Can you provide a better pic of the sticker for me to include in article?

Cheers

I'll shoot a better picture and send it to you via email. Will I find that on your site?
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-Matt I ♥ my ♂

Matt;

Yes...contact info on site.

Picture received, thanks!...I will be adding further details to article shortly.

Cheers

So Ron finds the problem independently but Matt has the sticker. Good to have you guys on the case.

ha;

As I state in the article, I just happened to notice this in the course of checking details of an Alt conversion...Volvo was acutely aware of the importance of not disconnecting the oe Alt output to the extent that they added the sticker...and Matt kindly pointed this out (I don't have a GT handy to refer to)...my suggested mod just makes the inadvertent disconnection (which can become more possible after 50 years) less likely to occur. Reliability is King!

Cheers

Alternators were a pretty new thing back in '67 all cars... especially European cars.

And it was standard practice to disconnect the battery to check charging system. Or start a car with a good battery, then disconnect it and put your dead battery in to re-charge.

I've done it a bunch of times myself...
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-Matt I ♥ my ♂