Light Bulb Needed? - Alfa Romeo Bulletin Board & Forums
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post #1 of 5 (permalink) Old 08-20-2018, 07:52 PM Thread Starter
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Light Bulb Needed?

I am in Aptos spending a few nights with relatives prior to going down to Carmel. I drove the 1967 step nose/V6 car so nothing but nothing is stock.

Anyway a lovely 5 hour drive from Magalia today except for some electrical gremlins. When I got to Aptos and parked, the car would not start. The battery, a side connection unit is in the trunk. One screw was loose and fine corrosion evident. Cleaned that up, put it on the charger and in a half hour it started. Alternator was working as we saw 13.4 volts with the engine running at the battery. So disconnected the battery and left it for an hour for longer charge. (with the battery disconnected) When I came back, it fired right up but no charging from alternator.

I ran out of daylight, but the red dash light did not illuminate with key on and engine not running. Also did not illuminate when running.

So. I suspect a blown bulb, which could be 50 years old for all I know. I think from my reading that a blown bulb in that circuit will prevent the alternator from exciting and making electricity.

Other options welcome.

Question: does anyone know the bulb ## to fit a 67 step nose? From what I have read, wattage can be crucial to proper operation.

Tomorrow AM I am going to test the circuit by first grounding the bulb wire out of the alternator to check for illumination, then pull the bulb which is kind of buried at the top of the dash.

I figure it's got to be a dead bulb or a lack of power to the bulb on the non-alternator side.

But in the meantime - anyone know if those bulbs are available?

Other ideas?

I promise a follow on with the answer

I hope to see some of you later this week.

Thanks!

Neil

Neil
1958 Touring Spider in restoration
1963 Giulia Spider "slightly" abnormale
1967 Giulia Sprint GT (aka Stepnose) with 3.0 V6 and a/c
Now full time in Magalia CA.
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post #2 of 5 (permalink) Old 08-22-2018, 11:50 AM
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Quote:
Originally Posted by Neil Martin View Post
Question: does anyone know the bulb ## to fit a 67 step nose? From what I have read, wattage can be crucial to proper operation.
I have spare (old) bulbs from warning lights on S2 Spiders. If it's that size/wattage, I can bring a few down to Monterey tomorrow.

Can you post a photo of the dead bulb?

1974 Spider
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post #3 of 5 (permalink) Old 08-27-2018, 06:52 AM Thread Starter
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The more story

Bob - thanks for the offer, I was off the grid by the time I saw the response and I can never get the iphone to work in posting to the BB.

The bulb is fine. I took the alternator out and had it tested - the shop said it was OK. Wrong. It had an intermittent fault and today it is coming out for replacement.

Neil
1958 Touring Spider in restoration
1963 Giulia Spider "slightly" abnormale
1967 Giulia Sprint GT (aka Stepnose) with 3.0 V6 and a/c
Now full time in Magalia CA.
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post #4 of 5 (permalink) Old 09-02-2018, 08:58 AM Thread Starter
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And the final story.

Turns out the alternator (which in my Frankenstein Alfa came from a Milano) had a cascading series of problems. #1 was that a wire on one of the brushes was intermittently connecting, leading to all sorts of odd electrical issues. A voltage gauge in the car would have revealed what was going on. But that was why the dash red light initially wouldn't come on - there was no ground path from ignition through the alternator when the brush was in broken condition. At the first trip to the shop it has wiggled back to working and the light worked and the alternator made power. Then the wire came completely undone, and the slip ring went bad, and thereafter the regulator, all in the span of the the Monterrey weekend. I made it almost home on battery power (a 50 mile tow to get the rest of the way)

While the alternator was at the shop, I tore into the dash, using electronic cleaner and wire brushes on all the terminals, cleaned the body/ground connections, and physically cut off the spade connectors on all the ground wires in the dash, soldered and shrink tubed all new connectors. Every thing now works MUCH better and brighter.
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Neil
1958 Touring Spider in restoration
1963 Giulia Spider "slightly" abnormale
1967 Giulia Sprint GT (aka Stepnose) with 3.0 V6 and a/c
Now full time in Magalia CA.

Last edited by Neil Martin; 09-02-2018 at 08:59 AM. Reason: error
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post #5 of 5 (permalink) Old 09-02-2018, 10:46 AM
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Quote:
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I think from my reading that a blown bulb in that circuit will prevent the alternator from exciting and making electricity.
Glad to hear you got your problem solved.

Just for the sake of discussion, I don't think that a blown indicator bulb would completely incapacitate an alternator. Yes, the current through the bulb does provide the start-up "excitement" that wakes up the alternator. But I think that even with a blown bulb, the alternator will self-excite once you rev the engine high enough.

As you wrote, the bulb's wattage influences how much current it passes; obviously an LED "bulb", which doesn't pass much current, isn't a good choice for this application.

Different alternators work in different ways. Some have a dedicated connection to the ignition switch that gets them going upon start-up.

Jay Mackro
San Juan Capistrano, CA

'63 Guilia spider
'65 Guilia Sprint GT
'67 Duetto
'91 164L

Last edited by Alfajay; 09-02-2018 at 10:48 AM.
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