Alfa Pages

[neo]

Hi!

I had a problem with the alternator. When I turned on the lights and the ventilator, the battery light on the dashboard started to lit a bit. Then I measured the voltage and I got 12.8 volts. In case nothing was turned on (except the engine) the voltage was 13.2 - 13.5 volts.

Then I've disassembled the alternator and I've determined that one pair of diodes were faulty. I've bought new diode package and a new voltage regulator. I've also changed the bearings, and I've checked the stator and the rotor. They were OK. I've assembled the unit and put everything back on the car. I've started the car and I've got the following measurements:
-When the car works at idle the voltage is 13.8 - 13.9V
-When the car works at idle with the lights and the vent on, the voltage drops to 13.5V.
In case that I rev the engine, voltage stays the same.

Is that voltage drop OK, or there should be always the same voltage?

The engine is 1.7 16V, the alternator is Bosch 65A.

Thanks!
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http://www.quartermile.ws/forum/viewthread.php?tid=889&page=1

[ZeNiTh-PbArM]

Hi,

that seems ok to me.
i assume you measure voltage at the battery terminals.
you shall get slightly higher readings when the unit is cold.

regards,
zp

[neo]

Yes, I've measured the voltage on the battery terminals.

Thanks!
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http://www.quartermile.ws/forum/viewthread.php?tid=889&page=1

[tvatavuk]

Neo
it is ok for car of that age. Best I could get from my P4 are exact same measurments.
At its peak, when everything is in great condition, you'll get 14.4V exact at idle, and maybe 14.1-14.2 with everything on.
Friend of mine (God have mercy on his soul) had this on his 16v.
You could start cleaning ground contacts around engine bay and behind mid console, to try to get those 14.1-14.4 figures, but I don't know is it worth it.

Main cause for voltage drop on 16v is usualy main ground on engine (L piece of metal screved on starter, has 2 screws where you screw around 7 ground wires)
Some other changed one of both of those thick ground cables from there to battery, so other just brided them with new ones.

They should give away free contact spray with any modern car older then 5 years
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Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

[neo]

[tvatavuk]

hmm I didn't know you could buy 14V for our alternators.
In that case since you bought 14V and not 14.4V regulator, everything is fine.
I guess you don't have red light burning in instrument cluster, after replacing diods?
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Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

[gritsop]

Hi,

I had my alternator rebuilt some time ago; I got hold of a second hand one, so I made a new one from the two.

Replaced the bearings, new brushes and polished the slip rings of the rotor. The original one had worn slip rings, deep enough not worth machining, so I used the second-hand one which had minimal wear.

I now have 13.95 V on idle and 13.65 on idle with lights on (high and low beam). Note that the battery is 27 months old.

Just my 2 cents.

Regards
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Thanassis Gritsopoulos
1991 Alfa 33 1.4 IE
2001 Alfa 147 1.6 Distinctive

http://www.alfa-restoration.co.uk
Parts Shop: www.alfa-restoration.co.uk/shop

[Guest]

[Vecchio Alfisti]

I notice that the book is quiet about the actual voltage output. The spec for the Ducellier says 13.75/14.35. One of the things that I have noticed is that if you double up the connection from the alternator to the battery, you can reduce the voltage drop and eliminate the red light when the windscreen wipers are slowly draging their weary way across the windscreen.
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Alfa 33 1.7 QF I think maybe now I m not so sure